DE102022000212A1 - Security feature for a verification system, system, method and computer program product for verifying an object provided with the security feature and method for producing a security feature - Google Patents

Abstract

A security feature for a verification system comprising: a viewport, wherein the viewport comprises: at least a first view comprising a plurality of segments, which forms a predetermined target view in encrypted form, the first view being detectable for at least a portion of the plurality of segments from at least a first viewing perspective or at least a first viewing perspective area, and the first view being designed to form the predetermined target view by applying a predetermined decryption code to the plurality of segments.

Description

The invention relates to a security feature for a verification system, a system, a method and a computer program product, each for verifying an object provided with the security feature, and a method for producing a security feature.

background

Optically variable security features and/or security elements can serve to protect an object provided with the security feature or security element. Such items can include, for example: a document of value, such as a banknote or a security, or an item of value, such as a product to be verified, including tobacco products, computer games, data carriers, luxury items or other goods.

For verification, security features and/or security elements are often optically variable and present two different views to an observer depending on the viewing angle. In the simplest case, this is a so-called "tilt image" with a view that is optically variable. Such views can be realized using microstructures.

It is already known to realize tilted images with micromirror arrays. Micromirrors can have dimensions from about 3 µm to 50 µm and can be arranged regularly (such as a “sawtooth grating”) or irregularly. Simple flip images are e.g. in WO 97/19821 A1 described. In other views, representations can also appear curved, as in WO 2014/060089 A2 or have mirrors with orientations that contain random variation, as in WO 2011/066991 A2 . Representations that are dependent on the viewing angle can also be realized with diffractive structures, in particular diffraction gratings (for example holograms based on regular diffraction gratings or matt structures based on irregular diffractive structures). In addition, it is known in the prior art to realize viewing-angle-dependent representations with microlenses and corresponding microimage arrays, which lie approximately in the focal plane of the lenses (“lens tilting image”). In this case, for example, rod lenses or spherical lenses can be used. Alternatively, instead of lenses, micro-concave mirrors can also be used, in the focal plane of which suitable micro-images are arranged. A third possibility is to write angle-dependent information directly into micro-concave or convex mirrors, such as in DE 102013021806 A1 .

Expensive testing devices are often used for the reliable verification of such security features, for example in money deposit machines or in bank note processing machines in commercial banks. In many cases, however, such complex devices are not available, for example when testing a security element "in the field" or when a security element is used to protect an extended or bulky object that cannot easily be brought into a testing device together with the object. There is also a need to generate security features in such a way that, if possible, they cannot be forged at all. However, the verification by the user should be as user-friendly, uncomplicated and simple as possible.

Summary of the Invention

It is therefore an object of the present invention to produce and/or provide a security feature that is particularly difficult or even impossible to counterfeit.

A further object is to produce and/or provide a secure and user-friendly verification system.

Another task consists in verifying an object to be verified in a particularly efficient and simple but nevertheless reliable manner.

One or more of these objects is/are solved by the main claim and the independent claims. Preferred embodiments are subject of the dependent claims.

According to one aspect, a security feature for a verification system comprises a viewport, wherein the viewport presents at least a first representation. The first representation includes a plurality of segments, the plurality of segments forming a predetermined target representation in encrypted form. The first representation can be detected for at least a part of the plurality of segments from at least a first viewing perspective or at least a first viewing perspective range. The first representation is configured to form the predetermined target representation by applying a predetermined decryption code to the plurality of segments.

The security feature offers a particularly high level of protection for the verification of an object provided with the security feature, such as a bank note, a document or an object to be verified. The security feature can be forged with difficulty or not at all. It is easily and efficiently decrypted by the user, for example by using a smartphone with an app for verification. The security feature is therefore particularly user-friendly. An optically variable security feature is thus provided which allows an authenticity check using a smartphone.

The hidden information of the first representation can be made visible using a suitable device (e.g. smartphone) by dividing the surface area containing this information into a large number of n surface elements and transferring the image information from these n surfaces to a target image that also has n surface elements. The shape, size, alignment and/or arrangement (e.g. sequence) of the image elements differ in the first view and in the target image, so that information that is visible to a viewer or possibly further machine-evaluable is only recognizable in the target image and in the encrypted one is not yet recognizable at first glance.

The security feature can be optically readable and/or detectable, ie it can have features that are in the visible wavelength range. This can be a feature that can be detected in one wavelength, several wavelengths or even a wavelength range, specifically in the optical or visible wavelength range. In this case, the representation (particularly in encrypted form) is visible to a user's eye. The security feature can additionally or alternatively be machine-readable, ie have features that are in the invisible wavelength range, for example in the UV and/or infrared range, and are readable in particular by a decryption system. In this case, the representation (in particular in encrypted form) can be recorded by a recording unit. It can - but does not have to - also be visible to a user. The feature can therefore also be detectable in the invisible wavelength range, namely in one wavelength, in several wavelengths or even in one wavelength range. The security feature can have visible and invisible detectable features, for example. The term “readable” means that the security feature can initially be detected and, in particular, decrypted. An optically readable security feature can be detected with the human eye, for example, but not decrypted by the viewer. An optical and/or machine-readable security feature can be recorded and decrypted or read using a decryption system. In this case, the decoding system requires a detection unit, such as a camera, which can detect features that the security feature has at all the wavelengths in order to be able to be read out correctly. If it is an optically readable security feature, reading it from the decryption system requires a detection unit that can detect light at the corresponding visible wavelengths, and if the security feature additionally or alternatively contains machine-readable features, a detection unit is required for correct reading can detect light at the corresponding invisible wavelengths. For this purpose, the decoding system can have one or more detection units, with the detection units being able to detect light at different wavelengths. The detection units can be sensitive to overlapping or non-overlapping wavelength ranges.

The security feature is suitable for a verification system for generating forgery-proof documents, banknotes, securities and/or goods. The security feature can be created directly on a substrate of the object of value to be protected (the document, the bank note, the security or the goods). The substrate of the object to be secured is also referred to as the target substrate. Alternatively, a security element with the security feature for the object of value to be protected is provided. The security feature is therefore preferably present in a security element which is provided in particular for protecting valuable documents or objects of value. The security element is incorporated (for example as a security thread) into the target substrate or (for example as a security patch or strip) applied to the target substrate, which in each case is in particular the substrate of the document of value or object of value. The security feature can form a security element or be part of a security element. The security element can comprise its own security element substrate (an inner or outer film layer). In addition, the security element be provided to a temporary transfer substrate. The security element is detached from the transfer substrate during transfer to the target substrate. In particular, the level of the display field on one of the substrates mentioned can be considered as the level of the security feature. The display field can be produced on one of the substrates mentioned (target substrate, security element substrate or transfer substrate). The security element can be a patch or a sticker or a decal to be stuck on, sealed, applied, introduced and/or worked into and/or into a (target) carrier material. The (target) substrate can also be packaging or the object to be protected or the object provided with the security feature itself. The security element with the security feature can be or will be applied to a banknote as a patch or strip, for example, or incorporated into the banknote structurally (for example as a security thread or patch). The display field, in particular the structure and/or parts of the structure that at least partially forms the display field, can be glued, sealed, or applied in some other way to the target substrate. For example, the display field can be a (multi)layer system that is produced on a carrier, then removed from it and then applied to the substrate, for example to a patch or to an object. Additionally or alternatively, the display field, in particular the structure and/or parts of the structure that at least partially forms the display field, can be incorporated into the substrate. In the latter case, the structure of the viewport may be woven, braided, bonded, or otherwise incorporated with the substrate, particularly the package and/or article.

The security feature includes a viewport. The viewport includes at least a first representation in graphical and/or pictorial form, that is, in physical and detectable form, the first representation including a plurality of segments. The first representation is therefore fractionated or subdivided or segmented into a large number of segments, with the segments being able to be rectangular, square, hexagonal or some other shape, in particular in shape and size, also varying among one another.

The segments form a predetermined target representation in encrypted form. Preferably, the segments depict the predetermined target representation in encrypted form, which means that the arrangement of the segments graphically depicts the predetermined target representation in encrypted form.

The first representation is detectable, visible and/or recognizable for at least a part of the plurality of segments from at least a first viewing perspective or at least a first viewing perspective range.

For example, an encrypted image can be displayed on a slide, which is then recorded by a smartphone. The smartphone can decode or reconstruct the image from the recording or photo in order to verify the object provided with it. The security feature can preferably be present as a tilting image view. Alternatively or additionally, the security feature can be integrated into an overall motif of a security element, such as film strips. Overall, security can thus be increased on the one hand and the risk of counterfeiting reduced and on the other hand the aesthetics can be improved as a result.

The (first) viewing perspective represents an axis between a viewing point on a substrate plane of the substrate, in which the first display field lies at least partially, and a position of an observer or a detection unit, the substrate plane of the substrate being spanned by a first axis and a second axis is, wherein the first viewing perspective is defined by a (first) rotation angle and a (first) viewing angle or tilt angle, wherein the (first) rotation angle is enclosed by the first axis and a first projection, which is a projection of the first viewing perspective onto the substrate plane and wherein the (first) viewing angle is enclosed by the second axis and a second projection, which corresponds to a projection of the (first) viewing perspective onto a plane that is perpendicular to the substrate plane and in which the second axis lies. The first viewing perspective is therefore defined by a first viewing angle and a first rotation angle. The second viewing perspective is defined by a second viewing angle and a second rotation angle

In general, the term viewing perspective means the perspective of the viewer or the detection unit in relation to the substrate plane, which is essentially formed or spanned by a representation or by the substrate with the representation. More precisely, it depends on the angles at which a light is detected with the said substrate plane, which is emitted by the image tion is scattered or reflected. The viewing angle or tilt angle changes when said substrate plane is tilted or tilted about a tilt axis that lies in the substrate plane. The angle of rotation changes under a rotation of said substrate plane about an axis of rotation that is perpendicular to this substrate plane. The viewing perspective area comprises at least one area for the viewing angle and/or the rotation angle. For example, the viewing perspective range can mean a range of viewing angles with a fixed rotation angle. The amount of the angles is arbitrary and therefore relative. For example, a viewing angle parallel to said substrate plane may be considered a 0° viewing angle. A top view would then correspond to a viewing angle of 90°. For example, a horizontal alignment of said substrate plane, in which a representation is perceived as horizontally aligned, can be regarded as 0° for the angle of rotation. However, this definition is arbitrary.

The representation is optically variable if the representation depends on whether the substrate plane is tilted about a tilting axis that lies in the substrate plane and/or whether the substrate plane is rotated about an axis of rotation perpendicular to the substrate plane. This allows a further degree of freedom to "hide" information in the direction of tilt and rotation. Some elements may require tilting to become visible, while other elements may require rotation to become visible.

For example, a portion of the plurality of segments may be viewable at a first viewing angle of 90°, while another portion of the plurality of segments may be viewable at a first viewing angle of 45°, or in another case at all angles for the viewing angle . Different parts, which may also overlap under certain circumstances, can therefore be visible at different first viewing angles. It can also be the case, for example, that a part of the multiplicity of segments is visible at a first viewing angle of 90° and at 45°, that is to say at a plurality of first viewing angles. In these cases, the detectability of a part of the plurality of segments depends on the viewing angle. In addition or as an alternative, there can also be a dependency of the detectability on the rotation angle for these or other segments.

The first representation is therefore optically variable for at least part of the plurality of segments. The dependency of an appearance of a representation on a viewing perspective is covered by the optical variability, whereby optical variability can also include other effects, which are described further below. "Optically variable", as used herein with regard to the dependence on the viewing perspective, means that different impressions or different subjectively perceptible and/or objectively detectable features in terms of shape, color and/or effects (three-dimensional (3D) effect; movement effect) appear and are dependent on the viewing angle and/or the rotation angle of a viewing perspective. Different features can only be detected by tilting and/or rotating. Tilting means the variation of the viewing angle with respect to the plane spanned by the substrate and/or the representation. More precisely, this means the variation of the angle that is included between an axis in the plane of the substrate and the viewing direction onto the plane. If light is detected from above, ie from above with a vertical view of the substrate, by an eye or a detection unit, this viewing angle is 90°. The axis about which it is tilted lies in the plane of the substrate. During rotation, the axis about which the rotation takes place lies on a perpendicular or perpendicular to said plane of the substrate.

In this case, tilting and rotating means the movement of the substrate on which the plane lies relative to the viewer or the detection unit. In addition or as an alternative, however, a change in the viewing perspective of the viewer or the detection unit in relation to the plane can also be meant.

An optical variability can also express itself additionally or alternatively as a variable reflection or non-transparency and a transmission or transparency, depending on whether a light is radiated through the rear side of the substrate.

The optical variability can generally be expressed in the fact that colors, brightness, structures, shapes are perceived differently under different circumstances. In this case, for example, a moving image and/or a hologram can also appear subjectively and/or be objectively detectable. With regard to this invention, the optical variability preferably not only appears subjectively for an observer, but can also be objectively detected by a detection unit, such as a camera. If the phenomenon requires stereoscopic vision on the part of the observer, a detection unit can, for example, also include two cameras for objectively detecting the effect, with the two cameras can be designed to capture two images of a representation from slightly different viewing perspectives and to transmit them to a processing unit, with the processing unit being able to determine the 3D effect. A single camera that is sensitive to one or more wavelengths can also be sufficient for other effects, such as color variation. Or, in this case, multiple cameras that are sensitive to different wavelength ranges can also be used. The detection unit can be designed to record individual images or moving images or films.

The first representation is designed to form the predetermined decrypted target representation using a predetermined decryption code or a mapping rule or an arrangement rule or a mapping rule on the plurality of segments. The encryption of the first representation is not a cryptographic encryption (which is intended to protect against computer-based decryption), but a graphic encryption that is generated by a targeted and predetermined disorder of the large number of segments. The predetermined decryption code is therefore also not a cryptographic encryption code, but rather a mapping rule in order to be able to create an order for the multiplicity of segments, so that the predetermined decrypted target representation results therefrom. As a rule, it is a question of a one-to-one assignment specification of the segments to themselves. The predetermined decryption code can therefore be understood as an operator which is applied to the multiplicity of segments in order to form the target representation. The predetermined decryption code can also consist of parts of a mapping rule that can be stored at different locations in order to increase the security of the encryption.

The plurality of segments of the at least one first representation can not only form the predetermined target representation in encrypted form, but also graphically depict it, so that the first representation can be optically detected in the visible and/or invisible wavelength range. The image is visible when it is in the wavelength range visible to an observer's eye. The image can be detected if it is in a wavelength range that can be detected or is sensitive to a detection unit (camera(s) and/or sensor(s)).

The predetermined target representation can be formed in general terms, but this does not necessarily mean that the predetermined target representation is also mapped. Additionally or alternatively, the first representation can therefore also be designed to map the predetermined target representation using the predetermined decryption code on the plurality of segments, specifically on an output unit, so that a user can view this target representation in decrypted form and verify the object to be verified can.

The case is preferred in which the predetermined target representation in decrypted form corresponds to or contains a meaningful image, for example the image of an object, which can and is graphically mapped or represented on the plurality of segments using the predetermined decryption code. For example, the target representation can be formed in a decrypted form, for example the image of an object, by a computing unit and also imaged or shown by means of a screen or display. The verification can therefore be carried out by capturing the target representation in encrypted form using optical means. The digital imaging of the target representation in decrypted form is followed by the at least partial depiction or representation of the target representation in decrypted form, so that the user and/or a machine or computing unit can determine that the decryption has been carried out correctly and whether the object to be verified is thus verified could become.

The viewport may further include: at least one second representation in graphical form, wherein the second representation is either at least partially optically non-variable and does not overlap with the first representation, and/or wherein the second representation (or a further second representation) is at least partially is optically variable and in particular can be at least partially detected under at least one second viewing perspective or at least one second viewing perspective area and wherein the at least one first viewing perspective does not correspond to the at least one second viewing perspective or the at least one first viewing perspective area does not overlap with the at least one second viewing perspective area and wherein the first representation preferably at least partially overlaps with the second representation.

The second representation can thus, for example, not be optically variable at least in part and cannot overlap with the first representation in terms of area in the display field. This means that the second representation can be detected or seen by the viewer from all angles when viewed from the front. The The second representation can, for example, contain information about which tools or means or tools can be used to record and/or decode the first representation. For example, the second representation can contain information about an app on a smart device.

Additionally or alternatively, the second representation can be at least partially optically variable. In that case, the second representation can have, for example, an apparent 3D curvature, a hologram, and/or the effect of a moving image and/or a dependence on the viewing perspective. In particular, the second representation can only be detectable from at least one second viewing perspective. In this case, the first and the second representation can be superimposed or overlapped in terms of area. The first representation can be visible and/or comprehensible from the at least one first viewing perspective and the second representation can be visible and/or comprehensible from the at least one second viewing perspective, so that essentially only either the first or the second representation is at least partially below each of the at least one first or second viewing perspective is detectable. Alternatively, the first and second representations do not overlap.

The second representation may be depicted as non-encrypted information or representation, and in any case may include additional information and/or aesthetic elements. The information can serve to ensure that the user or viewer of the security feature receives information about the object to be verified and/or an indication of how the verification can be carried out. For example, a bill may have a target representation of the first representation in encrypted form and a second representation in unencrypted form. The second representation may contain information about the denomination of the banknote, whereby the correct predetermined decryption code can be called up in order to correctly form and in particular map the target representation of the first representation. The second representation can have a barcode or a QR code, for example. The first representation, on the other hand, must not be understood as a barcode or QR code, since the target representation is decrypted purely graphically and not cryptographically. However, the first representation can also contain information about the object to be verified. For example, the decrypted target representation can graphically indicate the value of a banknote provided with it.

Alternatively, like the first representation, the second representation can have an encrypted second target representation, for which all features apply analogously to those for the first representation, with only one detectability of both representations from different viewing perspectives.

The use of a second representation can therefore provide further information and make securing an item to be verified even more secure against counterfeiting. Furthermore, the aesthetic impression can be improved by a second representation.

The optically variable security feature therefore shows at least two different representations depending on the viewing angle, of which at least one representation contains hidden information that can be read out with a suitable device—in particular a smartphone. The second representation serves to increase security compared to a single, optically non-variable encrypted representation. To assess the authenticity of a security feature, at least two properties can thus always be checked, namely the presence of at least two different representations depending on the viewing angle and the information hidden or encoded in the first view.

Each segment of at least a portion of the plurality of segments may each have a microstructure, wherein each microstructure may have a plurality of microstructure elements and the microstructure may be configured to block incident light from one of the at least one first viewing perspective or one of the at least one first viewing perspective range and preferably to reflect, focus and/or diffract under one of the at least one second viewing perspective or one of the at least one second viewing perspective range.

Microstructures are suitable for being able to produce optically variable representations based on reflection, focusing and/or bending of light. Microstructure elements can have micromirrors, microconcave mirrors, diffraction structures, diffraction gratings and/or microlenses. The microstructure elements of at least one segment are preferably of the same type, i.e. of a uniform design. Additional optical variability can be achieved if microstructures are coated with color-shifting thin-layer systems, for example, the color of which changes depending on the viewing angle. The microstructure elements can produce the types of optical variability described herein.

The size of each microstructure element can be between about 0.5 μm and 50 μm, in particular between about 0.8 μm and 40 μm and particularly preferably between about 1 μm and 30 μm.

A segment that has a square surface, for example, can have a side length of about more than 140 μm, in particular more than about 150 μm, preferably more than about 300 μm and particularly preferably more than about 600 μm. A detail of the target representation or a part of a pattern of the target representation can preferably also be recognizable or detectable in each segment by means of the microstructure element. For example, the viewer or the detection unit sees the detail of the target representation in the segment/s, such as, for example, a circular segment in one segment, a right-angled square within another segment and an acute-angled triangle in another segment. Therefore, the edge length should be above the resolution limit of the respective wavelength of the light, so that the structures can at least be correctly detected by the detection unit.

In the following, micromirrors will be used to describe in more detail which effects of optical variability can be used. Motifs generated by micromirrors are created by means of a directed reflection on the differently aligned micromirrors of the security feature. If all of the micromirrors in an area are oriented in the same direction, they reflect the light from a viewing perspective, for example a certain viewing angle or viewing angle range, towards the viewer. The other micromirrors may be oriented differently so that the area (the subject area) lights up brightly for the viewer and the surrounding area appears dark. If the security feature or the bank note is tilted and/or rotated further, the motif disappears again (everything is dark). Movement effects are created as follows. In order to display a representation, in particular a graphic image or a motif, such as a line, as a moving image depending on the viewing perspective, several areas are provided in the form of the image at different positions. As an example, when a bill is tilted, the image may move or appear to move because for each angle of tilt, portions of the image sequentially reflect at a slightly offset position. The movement effect becomes more fluid, for example, if not the entire surface but only narrower imaging contour lines reflect from certain viewing perspectives. A mapping change takes place as follows. The overall area of the first image also includes a further micromirror array - with a second correspondingly chosen alignment and different image and associated area and/or contour line. The micromirrors of the two groups can, for example, be arranged alternately next to one another. In the course of tilting, the entire field can initially appear dark; as the tilting progresses, the first image appears and then disappears again. By continuing to tilt in the same direction, the second image appears in the same place where the first image was seen. 3D effects or holograms are created as described below. A 3D effect includes the appearance of a bulge, i.e. an image that appears curved ("bulge effect") and images that appear to the viewer to be floating above or below the plane of the micromirrors. For a curved effect, the inclined surface of the image to be displayed is simulated at each location by a micromirror with a corresponding inclination. All in all, the local inclinations are "identical" for the viewer and a light reflection also travels on the micromirrors in the same way as it would for a flat surface. Stereo vision, i.e. vision with two eyes, is required for 3D effects, such as the apparent hovering of an image above a plane or an image extending out of the plane of the micromirrors, and one micromirror is arranged for each eye. The demand for micromirrors is therefore increasing.

The micromirrors can be in an irregular (in area and shape) or a regular arrangement. There can be several micromirrors (4x4 or 9x9) per pixel, which can be divided into different images or viewing perspectives, in particular viewing angles (nesting). The brightness of the reflections decreases with the degree of nesting. The nesting within a pixel can vary, making some areas appear lighter and other areas appear darker. As a rule, any specularly reflecting structure can serve as a micromirror. Non-diffractive plane reflective micromirrors can be used. These are usually produced by embossing a relief structure with the planar micromirror surfaces into a surface, for example into a surface made of UV-curing lacquer, which is then coated with a reflection-increasing layer, for example a metal and/or an HRI material . Concave mirrors or diffractively directed reflecting structures can be implemented analogously.

The first representation may be configured to include a mapping code for mapping uniquely and/or a rotation code for rotating by at least one angle and/or an expansion code for using the predetermined decryption code on the plurality of segments Expanding and/or a contraction code for contracting and/or a coloring code for coloring at least a portion of the plurality of segments to form the predetermined target representation.

Said codes or regulations are not to be understood as cryptographic codes. They are used for the digital analysis of the recorded graphic target representation in encrypted form in order to decrypt it graphically. The target representation in unencrypted form can be formed digitally and thus initially not yet physically (on a substrate) and then preferably graphically for an observer on a display. The codes can be used individually if there is only one form of encryption. However, it may also be the case that several codes have to be used, for example if there are rearrangements and rotations. The more forms of encryption used, the more secure the security feature. If there is no graphic representation, a computing unit can verify, based on the formation of the unencrypted target representation, whether the predetermined target representation could be correctly decrypted.

The mapping code is used for the one-to-one or bijective mapping of the unsorted or unordered or chaotic areal distribution of the segments onto itself, which (image) forms the target representation in encrypted form. In this case, the segments of the target representation are present in encrypted form, at least in part, in unsorted or unordered form. The mapping code is not to be understood as a cryptographic code, but as an arrangement rule or a mapping rule or a sorting rule, according to which the unsorted arranged segments are sorted and thus result in the unencrypted target representation. The target representation can therefore be obtained by the at least partially digital resorting or shifting or re-orientation or re-sorting or spatial arrangement or shifting or mapping of the segments of the first representation.

The rotation code is used to rotate the segments and should not be confused with the tilting or rotating described above. In this case, the segments of the target representation are present in encrypted form, at least partially in a rotated form, specifically in a form that is rotated to different extents, that is to say rotated by different angles. The tilting and rotating means a physical real movement of the substrate or the object to be verified. The rotation of the segments means in particular a digital rotation and no optical variability. This means that at least parts of the segments are rotated in the encrypted form of the target representation and can only be decrypted by correctly rotating them digitally back into the position that results in the decrypted target representation. In addition or as an alternative to the random distribution of the segments, the segments can therefore be rotated in order to encrypt the target representation and make it unrecognizable to the eye. The segments can be rotated, for example, by about 90°, 180° or by 270° when creating the encrypted target representation.

The expansion code and the contraction code are respectively for expanding and contracting the segments constituting the target representation in encrypted form. The segments of the target representation are in encrypted form, at least partially in expanded and/or contracted form, specifically in different sizes that are not suitable for forming the unencrypted form of the target representation (ab). An expansion and/or a contraction code can therefore be used to digitally decrypt the encrypted target representation. The target representation can therefore be formed by at least partially digitally expanding and contracting, ie enlarging and reducing, the segments of the first representation. The segments can be expanded and/or contracted to obscure or encrypt the target representation in addition to or as an alternative to the rotation and/or the (chaotic) resorting of the segments.

The coloring code is used to color at least part of the plurality of segments that make up the target representation in encrypted form. The segments of the target representation are at least partially in falsified colors or even colorless to the eye in encrypted form, in particular in such a way that the unencrypted form of the target representation becomes unrecognizable. For example, it may be the case that at least some of the segments can only be detected by a detection unit that is sensitive in the UV wavelength range and/or in the infrared range.

The first representation may be detectable for different parts of the plurality of segments under different first viewing perspectives or first viewing perspective ranges, wherein the first representation may be adapted to be detected using the predetermined decryption code comprising a viewing perspective code on the different parts of the plurality of segments that to form predetermined target representation (ab). In particular, the first viewing perspectives each include first viewing angles and/or the first viewing perspective ranges can each include first viewing angle ranges and the viewing perspective code can include a tilt code, it being possible for the first representation to be detectable for different parts of the plurality of segments under different ones of the first viewing angles or the first viewing angle ranges and wherein the first representation may be adapted to form the predetermined target representation (ab) by applying the predetermined decryption code comprising the tilting code to the different parts of the plurality of segments.

Additionally or alternatively, the first viewing perspectives can each include first rotation angles and/or the first viewing perspective ranges can each include first rotation angle ranges, wherein the viewing perspective code can include a rotation code, the first representation for different parts of the plurality of segments at different first rotation angles or the first rotation angle ranges may be detectable and wherein the first representation may be adapted to form the predetermined target representation (ab) by applying the predetermined decryption code comprising the rotation code to the different parts of the plurality of segments.

The tilt code is used, for example, to correctly assemble multiple images that were captured from different viewing angles. In this case, for example, part of the plurality of segments of the first representation can be detected and/or visible from a first first viewing angle and another part of the plurality of segments can be detected from a second first viewing angle. Furthermore, a second representation can also be detectable at viewing angles other than the first. The decoded target representation (ab) can be formed by correctly superimposing the images captured at the first and second first viewing angles. This can also result for more than just two first viewing angles.

The tilt code is used, for example, to correctly assemble multiple images that were captured from different viewing angles. For example, part of the plurality of segments of the first representation can be detected and/or visible from a first first viewing angle and another part of the plurality of segments can be detected and/or visible from a second first viewing angle. Furthermore, a second representation can also be detectable at viewing angles other than the first. The decoded target representation (ab) can be formed by correctly superimposing the images captured at the first and second first viewing angles. This can also result for more than just two first viewing angles. The same applies to the rotation code, which is used, for example, to correctly assemble multiple images that were captured at different rotation angles. For example, part of the plurality of segments of the first representation can be detected and/or visible at a first first angle of rotation and another part of the plurality of segments can be detected and/or visible at a second first angle of rotation.

All technical effects and advantages of the corresponding security features that are described herein also apply in an analogous manner to the systems, methods and the computer program product described below.

According to a further aspect, a system for verifying an object provided with a security feature comprises: one of the security features described herein; an item provided with the security feature; and a decoding system comprising: at least one capture unit, such as a camera and/or a sensor, which is designed to capture the first representation under the at least one first viewing perspective or the at least one first viewing perspective area and the second representation under the at least a second viewing angle; and a computing unit that is designed to form the predetermined decrypted target representation using the predetermined decryption code on the segments and in particular to depict it, for example, by means of a display.

The decoding system can also include an output unit, such as a screen and/or a display unit, which is designed to output, in particular to display, the predetermined target representation. The output unit can preferably be designed to display the decrypted target representation for a user who wants to verify an item.

The decryption system can form a unit, ie a decryption unit, ie it can be arranged within a single housing, and preferably comprise a smart device, in particular a smartphone.

The decryption system can include: a smart device, which can have the detection unit; and a server that can have the computing unit, wherein the smart device can be configured to transmit the captured first representation to the server and wherein the server can be configured to transmit the predetermined target representation in decrypted form to the smart device to transmit the smart device. In this case, the smart device can be designed to transmit the captured first representation with the target representation in encrypted form, that is to say before the decryption codes are applied to the server. Additionally or alternatively, the smart device can be designed to transmit the recorded first representation to the server in cryptographically encrypted form. In this case, the cryptographic encryption concerns the form of transmission and not the graphic encryption of the target representation. The smart device can have a screen or a display on which the decrypted target representation can be displayed for the user.

According to a further aspect, a method for verifying an object provided with the security feature described herein comprises: capturing the first representation in graphic form, i.e. capturing the multiplicity of segments which depict the target representation in encrypted form on the substrate, from the at least one first viewing perspective or the at least one first viewing perspective area, for example by means of the detection unit of the decoding system described herein; and applying the predetermined decryption code to the segments to form and preferentially map the predetermined target representation.

The method therefore preferably includes providing one of the security features described herein and one of the decryption systems described herein. In particular, the method can include tilting the security feature and/or the detection unit about an axis in the plane of the substrate and/or rotating the security feature and/or the detection unit about an axis perpendicular to the plane of the substrate in order to be able to detect all segments.

The method can also include: providing a security feature, the display field also having at least one second representation in graphic form, the second representation either being at least partially optically invariable and not overlapping with the first representation, or the second representation being at least partially optical is variable and in particular can be at least partially detected under at least one second viewing perspective or at least one second viewing perspective area and wherein the at least one first viewing perspective does not correspond to the at least one second viewing perspective or the at least one first viewing perspective area does not overlap with the at least one second viewing perspective area and wherein the first Representation preferably at least partially overlaps with the second representation. In this case, the method can include capturing the second representation in graphic form, in particular under the at least one second viewing perspective or the at least one second viewing perspective area by means of a capturing unit of a decoding system or by an observer.

The method may further include: graphically mapping and/or outputting the predetermined target representation in decrypted form and optionally graphically mapping and/or outputting the second representation.

The method can also include: comparing the predetermined target representation formed with a reference representation or a test representation or a verification representation for the predetermined target representation and optionally comparing the second representation with a reference representation for the second representation. The reference representation can be stored, for example, on a server, in an app and/or in a storage medium and a processing unit can access this reference representation after imaging and possibly after imaging the target representation and carry out the comparison with the target representation formed. The same applies to the second representation.

The method can also have the following steps: controlling a detection unit, such as a camera, and causing the detection unit to record an image and/or a video; optionally finding the security feature in the recorded image; if necessary, correcting the image, in particular with regard to perspective distortions; split if necessary an area of the corrected image into the n area elements corresponding in particular to the plurality of segments of the first representation; forming the predetermined target representation in decrypted form by applying at least one decryption code to the plurality of segments; optionally imaging and/or displaying the predetermined target representation and/or evaluating and/or verifying the predetermined target representation and displaying the evaluation result and/or the verification result.

According to a further aspect, a computer program product has machine-readable program instructions for a control unit of a data-processing device, in particular a smart device, which cause it to carry out one of the methods described herein.

According to another aspect, a method for producing a security feature comprises: providing a predetermined target representation, in particular in digital form; segmenting the predetermined target representation in digital form into a plurality of segments; generating a first representation by applying an encryption key to the plurality of segments to form the predetermined target representation in encrypted form and in particular in digital form, possibly at random; generating a decryption key based on the encryption key, wherein the encryption key may be a reciprocal operator or inverse function or inverse mapping; and establishing a viewport for the first representation such that the first representation is at least partially optically variable in graphical and physical form and is detectably legible, visible, and/or recognizable from at least a first viewing angle or at least a first viewing angle range.

Generating the first representation in digital form by applying the encryption key may include determining graphical information, detectability from at least a first viewing perspective, an optical property, and/or a color. It can therefore be determined or specified digitally which properties the later graphic first representation on the substrate should have. For example, it can be determined from which first viewing perspectives which segments will be detectable and/or visible, which segments may be rotated, or steps that otherwise contribute to the obscurity of the target representation. This information is then included in the encryption key.

Establishing the viewport may include transferring the digitally generated first representation onto and/or into a viewport, optionally onto or into a substrate, such that the first representation is then physically present in graphical form.

The method may further include: providing a second representation; and producing the substrate further comprising the second representation, so that the second representation is at least partially optically variable in graphic and physical form and is detectably readable and/or visible and/or recognizable or perceptible from at least one second viewing angle or at least one second viewing angle range, wherein the first representation and the second representation at least partially overlap in the viewport and wherein the at least one first viewing angle does not correspond to the at least one second viewing angle or the at least one first viewing angle range does not overlap with the at least one second viewing angle range.

The production of the display field can include transferring the digitally generated second representation into the display field, in particular on and/or in the substrate, so that the second representation is physically present.

• Eineindeutiges Abbilden von zumindest einem Teil der Vielzahl der Segmente entsprechend eines Abbildungs-Verschlüsselungscodes; und/oder
• Drehen von zumindest einem Teil der Vielzahl der Segmente um mindestens einen Winkel entsprechend eines Dreh-Verschlüsselungscodes; und/oder
• Expandieren von zumindest einem Teil der Vielzahl der Segmente entsprechend eines Expansions-Verschlüsselungscodes; und/oder
• Kontrahieren von zumindest einem Teil der Vielzahl der Segmente entsprechend eines Kontraktions-Verschlüsselungscodes; und/oder
• Färben von zumindest einem Teil der Vielzahl der Segmente entsprechend eines Färbungs-Verschlüsselungscodes; und wobei das Erzeugen des Entschlüsselungscodes basierend auf dem Verschlüsselungscode entsprechend umfasst:
• Erzeugen eines Abbildungs-Codes basierend auf dem Abbildungs-Verschlüsselungscode; und/oder
• Erzeugen eines Dreh-Codes basierend auf dem Dreh-Verschlüsselungscode; und/oder
• Erzeugen eines Expansions-Codes basierend auf dem Expansions-Verschlüsselungscode; und/oder
• Erzeugen eines Kontraktions-Codes basierend auf dem Kontraktions-Verschlüsselungscode; und/oder
• Erzeugen eines Färbungs-Codes basierend auf dem Färbungs-Verschlüsselungscode.

Generating the first representation by applying an encryption key to the plurality of segments may include:

• uniquely mapping at least a portion of the plurality of segments according to a mapping encryption key; and or
• rotating at least a portion of the plurality of segments by at least one angle according to a rotation encryption key; and or
• expanding at least a portion of the plurality of segments according to an expansion encryption key; and or
• contracting at least a portion of the plurality of segments according to a contraction encryption key; and or
• coloring at least a portion of the plurality of segments according to a coloring scrambling code; and wherein generating the decryption key based on the encryption key comprises:
• generating a mapping code based on the mapping encryption code; and or
• generating a spin code based on the spin encryption code; and or
• generating an expansion key based on the expansion encryption key; and or
• generating a contraction code based on the contraction encryption code; and or
• generating a coloring code based on the coloring encryption code.

• Bestimmen von verschiedenen Betrachtungswinkeln bzw. Kippwinkeln und/oder Rotationswinkeln für verschiedene Teile der Vielzahl der Segmente, sodass die verschiedenen Teile der Vielzahl der Segmente unter verschiedenen ersten Betrachtungsperspektiven oder ersten Betrachtungsperspektivbereichen erfassbar sein werden;
• wobei das Übertragen der ersten Darstellung auf das Substrat in einem Darstellungsfeld umfasst: Ein- und/oder Aufbringen einer Mikrostruktur für jedes Segment, wobei jede Mikrostruktur unter der jeweiligen ersten Betrachtungsperspektive oder dem ersten Betrachtungsperspektivbereich einfallendes Licht reflektiert, fokussiert und/oder beugt; und
• wobei das Erzeugen des Entschlüsselungscodes basierend auf dem Verschlüsselungscode ein Erzeugen eines Verkippungs-Codes und/oder Rotations-Codes basierend jeweils auf einem Verkippungs-Verschlüsselungscode und/oder einem Rotations-Verschlüsselungscode umfasst, wobei die ersten Betrachtungsperspektiven jeweils einen ersten Betrachtungswinkel und einen ersten Rotationswinkel aufweisen.

Digitally generating the first representation by applying an encryption key to the plurality of segments may include:

• determining different viewing angles or tilt angles and/or rotation angles for different parts of the plurality of segments, so that the different parts of the plurality of segments will be detectable from different first viewing perspectives or first viewing perspective ranges;
• wherein transferring the first depiction to the substrate in a viewport comprises: applying and/or depositing a microstructure for each segment, each microstructure reflecting, focusing, and/or diffracting light incident under the respective first viewing perspective or viewing perspective range; and
• wherein generating the decryption code based on the encryption code comprises generating a tilt code and/or rotation code based on a tilt encryption code and/or a rotation encryption code, respectively, wherein the first viewing perspectives each have a first viewing angle and a first rotation angle .

character list

• 1a Figure 12 is a schematic perspective view of an item provided with a security feature according to one embodiment;
• 1b is a schematic plan view of the subject matter of FIG 1a , which is provided with a security feature;
• 2a Figure 12 is a geometric representation of a viewing perspective;
• 2 B 12 is a schematic representation of a system for verifying an item provided with a security feature according to one embodiment;
• 3 12 is a schematic representation of the generation of a security feature by encryption and the decryption of the security feature according to one embodiment;
• 4 12 is a schematic representation of the generation of a security feature by encryption and the decryption of the security feature according to one embodiment;
• 5 is a schematic representation of the generation of a security feature by encryption and the decryption of the security feature according to a further embodiment;
• 6 is a schematic representation of the generation of a security feature by encryption and the decryption of the security feature according to a further embodiment; and
• 7 12 shows photographic representations of a security feature according to an embodiment.

Detailed description of the drawings

Unless otherwise noted, the same reference numbers are used below for the same elements and those with the same effect. A redundant description of recurring features is avoided. The various embodiments and features of the figures described below can be expressly combined and are not to be understood as complete versions.

1a 12 is a schematic perspective view of an object 10 provided with a security feature 1 according to an embodiment. The object 10 has a substrate 2 . The substrate 2 forms the basis for a display field 3. The display field 3 has a display 4, 5 which is optically variable. The substrate 2 with the representation 4, 5 lies in a substrate plane E. The detectability and/or visibility of the representation 4, 5 can depend on a tilting movement of the substrate plane E in a tilting direction K about a tilting axis KA. Additionally or alternatively, the detectability and/or visibility of the representation 4, 5 can depend on a rotational movement of the substrate plane E in a rotational direction R about a rotational axis RA. The tilting axis KA lies in the substrate plane E and the rotation axis RA is perpendicular to the substrate plane E. 1b 12 is a schematic plan view of item 10 of FIG 1a , which is provided with a security feature 1. 1a and 1b therefore show the security feature 1 from two different perspectives, which are based on the below 2a be described in more detail.

2a is a geometric representation of the viewing perspective 6. The substrate plane E can be spanned by two axes, a first axis A1 and a second axis A2. In this figure, the first axis A1 coincides with the tilting axis KA. The viewing perspective 6 corresponds to an axis between a viewing point BP on a substrate plane E of the substrate 2, in which the first display field 3 lies or is, and a position P of an observer or a detection unit. The viewing perspective 6 is defined by a rotation angle α and a viewing angle β. The angle of rotation α is enclosed by the first axis A1 and a first projection 6a, which corresponds to a projection of the viewing perspective 6 onto the substrate plane E. The first viewing angle β is enclosed by the second axis A2 and a second projection 6b, which corresponds to a projection of the viewing perspective 6 onto a plane E' which is perpendicular to the substrate plane E and in which the second axis A2 lies.

2 B is a schematic representation of a system 100 for verifying an object 10 provided with a security feature. The system 100 for verifying the object 10 provided with the security feature 1 comprises the security feature 1, the object 10 which is provided with the security feature 1 or the substrate 2 of the security feature 1 and a decryption system 9. The decryption system 9 has a detection unit 7, which can detect the representation 4, 5, and a computing unit 8, which calculates the predetermined target representation 4c (not shown here) using the predetermined decryption code on the segments 4a ( not shown here) form, in particular can depict. The first representation 4 is encrypted as described herein. If necessary, the second representation 5 can also be encrypted according to the embodiments described herein.

The decryption system 9 has a smart device 9' and optionally a server 9". The smart device 9' includes the acquisition unit 7, which can acquire the representation 4, 5. The representation 4, 5 can have an encrypted target representation. The decryption or The encrypted target representation can be evaluated by the processing unit 8 of the smart device 9' and/or by an external processing unit 8, for example a processing unit 8 of a server 9". The decrypted target representation can then be displayed on an output unit 11 for a user to view. The output unit 11 can be a display of the smart device 9' and/or the screen of an external computing unit 8. The encrypted representation, which is graphically encrypted by defacement, for example by segmenting and rearranging the segments, can be sent by the smart device 9' to a Server 9 "are transmitted. This transmission, i.e. the transmission of the data packet with the graphically encrypted target representation, can in turn take place encrypted, namely cryptographically. The processing unit 8 of the server 9 "can decrypt the data packet and thus unpack the graphically encrypted target representation. The computing unit 8 can then use the decryption code to decrypt the graphically encrypted target representation by digitally assembling the segments in such a way that they form the predetermined target representation. The decrypted, predetermined target representation can then be transmitted to the smart device 9' again as a data packet, for example as a cryptographically encrypted data packet. The smart device 9' can display the decrypted predetermined target representation using the display 11 so that the user can verify the object.

Alternatively, the processing unit 8 of the smart device 9' can decrypt the graphically encrypted target representation using the decryption code. To do this, the decryption code can already be found on present on the smart device 9`, or for example be transmitted from the server 9" to the smart device 9`. For example, a second representation 5, as described herein, can also be transmitted from the smart device 9` to the server 9` . The server 9" can then transmit the correct decryption code to the smart device 9' based on the second representation 5.

Various options for graphically encoding the first representation are described below.

• 3 ist eine schematische Darstellung der Erzeugung durch Verschlüsseln und der Entschlüsselung eines Entschlüsselung eines Sicherheitsmerkmals 1 gemäß einer Ausführungsform. Die erste Darstellung 4 weist eine Zieldarstellung in verschlüsselter Form 4b auf. Es handelt sich um eine (chaotische) Umsortierung der Segmente 4A. Die erste Darstellung 4 ist dazu ausgelegt, unter Anwendung eines vorbestimmten Entschlüsselungscodes, und zwar einer Abbildungsvorschrift auf die Vielzahl der Segmente 4a, die vorbestimmte entschlüsselte Zieldarstellung 4c zu bilden.

Hidden information "A" by four unordered segments:

• 3 1 is a schematic representation of the generation by encryption and the decryption of a security feature 1 according to an embodiment. The first representation 4 has a target representation in encrypted form 4b. It is a (chaotic) resorting of the segments 4A. The first representation 4 is designed to form the predetermined decrypted target representation 4c using a predetermined decryption code, namely a mapping rule on the plurality of segments 4a.

A letter “A” is hidden or encoded in the first representation 4 of the optically variable security feature. The method 300 for generating the target representation or the initial image in encrypted form 4b runs as follows: First, a predetermined target representation with the information "A" is generated 310 ( 3(a) ). The first representation with the information to be hidden is then divided 320 into n segments 4a or surface elements. Only n=4 segments 4a are used here for a clear explanation. 3(b) shows a particularly simple division into four square segments 4a, each of equal size, which are numbered 1-4. To generate or form 330 the encrypted first representation 4b, the contents of the n segments 4a are swapped, ie a one-to-one assignment of each of the four segments 4a of the predetermined target representation 4c to a different segment 4a of the encrypted representation is made, for example using a suitable random algorithm ie each segment 4a of the predetermined target representation 4c is assigned exactly one segment 4a of the encrypted first representation 4b and vice versa, each segment 4a of the encrypted first representation 4b is assigned exactly one segment 4a of the predetermined target representation 4c. Mathematically, this corresponds to a bijective mapping of the numbers {1,2,...,n} onto themselves. A possible assignment is shown in the following table: Table 1 Segments of the decrypted predetermined target representation segments of the encrypted predetermined target representation 1 2 2 4 3 3 4 1

According to this assignment rule or predetermined encryption rule, the encrypted target representation 4b of the first representation 4 is then generated, i.e. the image content or the representation of the first (1) segment 4a of the predetermined target representation in the second (2) segment 4a of the target representation in encrypted form 4b inserted, etc. The result of this rearrangement is in 3(b) shown. Despite the selection of only n=4 segments, the information "A" is no longer recognizable or at least only with difficulty. Steps 310 through 330 are preferably performed digitally. After the formation of the target representation in encrypted form 4b, the physical application and/or introduction of the pattern or the target representation in encrypted form 4b takes place on and/or in a substrate 2. The target representation in encrypted form 4b includes in the physical form on the Substrate 2 optically variable properties as described herein.

For verification, the target representation in encrypted form 4b of 3(c) captured with a camera from a suitable viewing perspective and shown on a display as a target representation. For this purpose, a predetermined decryption code or a suitable algorithm is used in order to “swap back” the contents of the individual segments 4a of the target representation in encrypted form 4b. The allocation from Table 1 is used for this purpose, with the content of the second (2) seg ments 4a of the target representation is inserted in encrypted form 4b. The content of the fourth (4) segment 4a of the target representation in encrypted form 4b is inserted into the second (2) segment 4a of the predetermined target representation in decrypted form 4c, etc. The assignment from Table 1 thus serves as a "key" that defines the encryption and contains the decryption rule. By applying 210 the predetermined decryption code to the segments 4a, the target representation in encrypted form 4b ( 3(c) ) the target representation in decrypted form 4c ( 3(d) ) are calculated, formed and mapped.

The shape of the first representation 4 can be rectangular and in particular square, for example, and can be divided into individual rectangular and in particular square segments 4a. The rectangular or square segments 4a are preferably arranged on a regular rectangular grid, advantageously in particular a square grid. For better integration in form and/or motif of a security feature (or security element), the first representation can be designed with other advantages but also other forms which, for example, fit better into an overall motif. The n segments 4a can continue to be arranged on a regular grid in a comparatively simple and therefore advantageous manner, always with the same shape or alternatively with a varying shape. In addition to the already mentioned rectangular segments 4a on a rectangular grid, for example, hexagonal surface elements on a hexagonal grid can also be used.

• 4 ist eine schematische Darstellung der Erzeugung eines Sicherheitsmerkmals 1 durch Verschlüsseln und der Entschlüsselung des Sicherheitsmerkmals 1 gemäß einer Ausführungsform. Bevorzugt werden jedoch mehr als n=4 Segmente 4a verwendet, um eine Verschlüsselung zu erzeugen, die ein hohes Maß an Sicherheit erzeugt. Die Ausführung der 3 dient daher vor allem zur Beschreibung des Konzeptes der Verschlüsselung durch Unordnung der Segmente 4a. In 4 wird eine Ausführung der Verschlüsselung durch Unordnung mit 269 Segmenten 4a beispielhaft beschrieben. Die vorbestimmte Zieldarstellung der Wertzahl „50“ ist in n=269 Segmente zerlegt bzw. segmentiert (siehe 4(a)). Die Segmente 4a sind auch in dieser Ausführung quadratisch, allerdings füllt die Gesamtheit der Segmente 4a keine quadratische Fläche vollständig aus sondern es sind Flächenbereiche des Darstellungsfeldes 3 ausgespart, in denen keine Segmente 4a vorliegen, die zur Verschlüsselung beitragen. Die erste Darstellung 4 wird in diesem Bereich daher nicht verschlüsselt. Dieser Bereich, in dem keine Segmente 4a vorliegen, dient zur Darstellung eines Logos, das einen Benutzer auf eine zugehörige App hinweisen kann. Dies ist eine mit der ersten Darstellung 4 nicht überlappende zweite Darstellung 5. Neben dem verschlüsselten Teilbereich der ersten Darstellung 5 liegt in dieser Ansicht also ein weiterer, nicht verschlüsselter Teilbereich der zweiten Darstellung 5 vor, der optisch variabel sein kann aber nicht sein muss. Beispielsweise kann die zweite Darstellung 5, also das dargestellte Logo einen Wölbeffekt aufweisen.

Hidden information "50" through 269 unordered segments:

• 4 is a schematic representation of the generation of a security feature 1 by encryption and the decryption of the security feature 1 according to an embodiment. However, more than n=4 segments 4a are preferably used in order to generate an encryption that generates a high degree of security. The execution of 3 therefore serves primarily to describe the concept of encryption by disordering the segments 4a. In 4 an execution of the encryption by disordering with 269 segments 4a is described by way of example. The predetermined target representation of the value number "50" is broken down or segmented into n=269 segments (see 4(a) ). The segments 4a are also square in this embodiment, but the totality of the segments 4a does not completely fill a square area, rather surface areas of the display field 3 are left open in which there are no segments 4a that contribute to the encryption. The first representation 4 is therefore not encrypted in this area. This area, in which there are no segments 4a, is used to display a logo that can refer a user to an associated app. This is a second representation 5 that does not overlap with the first representation 4. In addition to the encrypted sub-area of the first representation 5, there is another, non-encrypted sub-area of the second representation 5 in this view, which can be optically variable but does not have to be. For example, the second representation 5, that is to say the logo shown, can have a curved effect.

Also in the 4 a predetermined target representation 4c is segmented 320 ( 4(a) ) and the segments 4a of the predetermined target representation 4c, i.e. the image contents in the first partial area, are re-sorted 330 on the basis of a random number sequence, for example, so that the predetermined target representation results in encrypted form 4b ( 4(b) ). If the predetermined target representation is captured in encrypted form 4b with a smart device 9' such as a smartphone, a suitable app can be called up and the decrypted predetermined target representation 4c can be formed 210 from the captured image or photo and the associated predetermined decryption code by a unique Allocation of the segments 4a of the predetermined target representation in encrypted form 4b. The smartphone is used here as a decryption system 9 with a computing unit 8 and an output unit 11, such as a display. After the formation of the decrypted, predetermined target representation 4c, it can then also be shown on the display for the user, so that the verification can take place.

Such an app may need additional information and additional steps may be required. For example, at least one of the following steps of a method for verification can include: controlling the camera and recording an image of a security feature; finding the security feature in the captured image; if necessary, image corrections (in particular correction of perspective distortions); Display or imaging of the target representation and/or the verification result.

• 5 ist eine schematische Darstellung der Erzeugung eines Sicherheitsmerkmals 1 durch Verschlüsseln und der Entschlüsselung des Sicherheitsmerkmals 1 gemäß einer weiteren Ausführungsform. In einer Weiterbildung der Ausführungsformen kann die segmentierte Zieldarstellung in verschlüsselter Form 4b in mehrere Teilansichten aufgeteilt werden, die jeweils unter verschiedenen Betrachtungsperspektiven 6, insbesondere verschiedenen Betrachtungswinkeln β sichtbar und/oder erfassbar sind. Es werden also nicht alle Segmente 6a der Zieldarstellung in verschlüsselter Form 4b bei einer Betrachtungsperspektive 6 sichtbar/erfassbar. Die anderen Segmente 6a der Zieldarstellung in verschlüsselter Form 4b werden erst bei einer anderen Betrachtungsperspektive 6 sichtbar/erfassbar. Zur Berechnung der Zieldarstellung in entschlüsselter Form 4c werden zunächst die unter unterschiedlichen Betrachtungsperspektiven 6 erfassten Segmente 4a überlagert und dann wird der Entschlüsselungscode auf die Darstellung angewandt, die durch Überlagerung der Segmente 4a, und zwar die Zieldarstellung in verschlüsselter Form 4b entsteht.

Hidden information "A" through four unordered segments, each of which can be viewed from different perspectives:

• 5 is a schematic representation of the generation of a security feature 1 by encryption and the decryption of the security feature 1 according to a further embodiment. In a further development of the embodiments, the segmented target representation in encrypted form 4b can be divided into a number of partial views which are each visible and/or detectable from different viewing perspectives 6, in particular different viewing angles β. Thus, not all segments 6a of the target representation in encrypted form 4b are visible/detectable in a viewing perspective 6. The other segments 6a of the target representation in encrypted form 4b only become visible/detectable from a different viewing perspective 6 . To calculate the target representation in decrypted form 4c, the segments 4a recorded from different viewing perspectives 6 are first superimposed and then the decryption code is applied to the representation that is created by superimposing the segments 4a, namely the target representation in encrypted form 4b.

The concept is illustrated below by way of example using the hidden image information “A”, the encrypted representation of which only results when all segments 4a are superimposed, which can be detected from different viewing perspectives.

First, the predetermined representation of the image information "A" is generated or otherwise provided ( 5(a) ). The predetermined representation with the information to be hidden is then divided into n segments 4a ( 5(b) ). For a clear explanation, only n=4 segments 4a are used again. In 5(b) a simple division into four square segments 4a, each of equal size and numbered 1-4, is shown. To generate the target representation in encrypted form 4b, the contents of the n segments 4a are swapped, ie a one-to-one assignment of each of the four segments 4a of the predetermined target representation in decrypted form 4c is generated using a suitable random algorithm, ie each segment 4a or pixel of the Predetermined target representation in decrypted form 4c is assigned exactly one segment 4a of the predetermined target representation in encrypted form 4b and vice versa, each segment 4a of the target representation in encrypted form 4b is assigned exactly one segment 4a of the target representation in decrypted form 4c (mathematically this corresponds to a bijective mapping of the numbers {1,2,...,n} to itself). A possible assignment is shown in Table 2 below: Table 2 Segments of the decrypted predetermined target representation segments of the encrypted predetermined target representation Visible and/or detectable under viewing angle β 1 2 30° 2 4 75° 3 3 60° 4 1 45°

The values in Table 2 are to be understood as examples to describe the concept. According to this assignment, the target representation is formed in encrypted form 4b, i.e. the image content of the first (1) segment 4a of the predetermined target representation 4c is inserted into the second (2) segment 4a of the target representation in encrypted form 4b, etc. The result of this rearrangement is in 5 (c-1 to c-4). Despite the small choice of n=4, the information “A” is no longer recognizable, or at least only with difficulty. In this embodiment, the individual segments 4a (1-4) are not simultaneously visible from a viewing angle β, which offers additional security against forgery.

The view of the target representation in encrypted form 4b as shown in 5 (c-1 to c-4) is shown as an example, segment 4a for segment 4a is imaged by an optically variable security feature from different viewing angles β. Several segments 4a can also be imaged simultaneously at one viewing angle β and other segments 4a at another viewing angle β. Identical segments 4a can also be imaged from more than one viewing angle β. Relating to 5 a viewing angle β is spoken of with regard to the target representation in encrypted form 4c. In general, however, it can also be a viewing perspective 6 which also includes or represents a rotation angle α. The representation shown here means the first representation 4 according to the claims and the viewing angle β or the viewing angles β means the first viewing angle(s) according to the claims.

In addition to the first representation 4 with encrypted information, a second representation 5 (not shown here) can be "laid" over the first representation 4 so that, for example, in plan view (viewing angle β = 90°) image information can be recorded and/or visible and in another tilted view, for example under the angles β mentioned in Table 2, the individual segments 4a of the encrypted target representation 4b can be detected/visible one after the other, for example to increase the attractiveness and/or the counterfeit security of the security feature.

For verification, the optically different variable segments of the 5 (c-1 to c-4) are recorded at the respective viewing angles b with a recording unit. The processing unit of the detection unit 8 or an external processing unit 8 can form the predetermined target representation 4c using the predetermined decryption code and in particular map it via an output unit.

The segments 4a of the target representation in encrypted form 4b are “exchanged back” using a suitable algorithm, the predetermined decryption code. The assignment rule from Table 2 is used for this. In the present embodiment, for example, the content of the second segment 4a of the target representation in encrypted form 4c is inserted into the first segment 4a of the target representation in decrypted form 4c. The assignment from Table 2 thus serves as a "key" to get out of the encrypted view into (c-1 to c-4) the target image in to be able to generate, which contains the hidden information "A". The shape of the image or image area to be encrypted (hereinafter “first sub-area”) can be as described above with reference to 3 is described, be designed.

In this version of the 5 the dependency of the display on a viewing angle β is described. In another embodiment, however, there can also be a dependency on a rotation angle α as an alternative or in addition.

• 6 ist eine schematische Darstellung der Erzeugung eines Sicherheitsmerkmals 1 durch Verschlüsseln und der Entschlüsselung des Sicherheitsmerkmals 1 gemäß einer weiteren Ausführungsform. In dieser weiteren Ausführung soll in der ersten des optisch variablen Sicherheitsmerkmals ein Buchstabe „A“ versteckt bzw. kodiert werden. Um die zugehörige verschlüsselte Zieldarstellung 4b zu erzeugen, wird zunächst ein Bild dieser Information „A“ generiert oder bereitgestellt 310 (6(a)).

Hidden information "A" by four disordered and rotated segments:

• 6 is a schematic representation of the generation of a security feature 1 by encryption and the decryption of the security feature 1 according to a further embodiment. In this further embodiment is in the first of the optically variable security feature, a letter "A" can be hidden or encoded. In order to generate the associated encrypted target representation 4b, an image of this information "A" is first generated or provided 310 ( 6(a) ).

The target representation in decrypted form 4c with the information to be hidden is then divided into n segments 320 ( 6(b) ). To generate the target representation in encrypted form 4b, the contents of the n segments are swapped, as already explained in FIG 3 and 5 . In an additional step, the n segments 4a are rotated through a specific angle. In this version, rotation angles of 0°, 90°, 180° and 270° are possible. Alternatively, the rotation can also take place before swapping the contents of the surface elements. A possible mapping is shown in the following table: Table 3 Segments of the decrypted predetermined target representation segments of the encrypted predetermined target representation angle of rotation 1 2 90° 2 4 180° 3 3 270° 4 1 90°

According to this assignment or mapping rule, the target representation is then generated in encrypted form 4b 330 ( 6(c) ). The image content of the first (1) segment 4a of the target representation in decrypted form 4c is inserted into the second (2) segment 4a of the target representation in encrypted form 4b and rotated by 90°, etc.

The result of the rearrangement is already in 3(c) shown. The result of the rearrangement with rotation is in 6(c) shown. Despite the small selection of n=4 segments 4a and the additional rotation of the individual segments 4a, the information “A” is no longer recognizable or is still difficult to recognise. A view like in 6(c) shown by way of example can be presented by an optically variable security feature at a first viewing angle β.

For verification, the view can be turned off 6(c) are recorded with a camera at a suitable viewing angle β and are assembled 210 to form the predetermined target representation using the predetermined decryption code ( 6(d) ). The segments are swapped and rotated according to the assignment in Table 3.

Additional or alternative designs

The described embodiments have square segments on a square grid, the segments 6a being rearranged and/or rotated for encryption or decryption. If necessary, this may already be sufficient for encryption.

In more detailed versions, the segments 6a of the predetermined target representation can also have other regular or irregular shapes in decrypted and/or encrypted form. In particular, the segments 6a of the predetermined target representation in decrypted form 6c can also have different forms than the associated segments 6a of the predetermined target representation in encrypted form 6b, or the image content can be additionally rotated with the same form, for example. It is essential that the corresponding software (e.g. an app on the smartphone) can map the image content from the segments 6a of the encrypted target representation 4b with a predetermined method and a predetermined code well enough into the corresponding segments 4a of the predetermined target representation 4c and the the necessary information is available as a "key". The key can contain different information, i.e. in addition to simple picture element numbers such as shown in Table 1, e.g. in the case of a rotation of the segments 6a the corresponding angle of rotation or in the case of varying segment or tile shapes a suitable description of the tile shapes in the encrypted image or in the Target presentation 6c.

The required key can already be programmed into an app in a decryption system. It can be downloaded from an app or, for example, from a server. It can be particularly secure if an app does not carry out the decryption itself but, for example, transfers the encrypted target representation 4b to a server, which then sends back a decrypted target representation 4c. Even if the present description mainly describes that an encrypted target representation 6b is to be decoded on the basis of the corresponding code or key or rule, in practice an app can also be encrypted with a data set of one or many encrypted and associated decrypted ones instead of with the key Views or representations work. The app would then only use image recognition to check whether the recorded image of the representation matches a stored encrypted representation and then map the associated decrypted representation. This method can be inexpensive in practice and/or used by app providers who do not have the key/code themselves.

If a “curved flip image” is formed and a representation that appears curved is generated, the curved impression is also retained in the back-calculated target image. The micromirrors can, for example, be molded into an embossing lacquer and provided with a reflection-increasing coating. When used as a security feature, the embossing heights are advantageously less than 50 μm, preferably less than 10 μm and particularly preferably less than 5 μm. The coating of the micromirrors can be metallic or highly refractive. Color shifting coatings can also be used to increase security.

In some of the embodiments described herein, the security feature can also be individualized. For example, tilting images can be written or embossed under microlens arrays by laser, with an individual motif being able to be used relatively easily for each security feature. For example, individual information can be inscribed, applied and/or introduced, such as a serial number of a banknote or the date of birth or photo of an ID card holder. In the case of ID documents, this can lead to a significant increase in security, since a forger not only has to imitate the optical variability, but also needs the key in order to generate a suitable encrypted image for the forged ID.

A second representation can in principle be designed as desired. If embossed structures or microstructure elements, in particular micromirrors or diffraction structures, are used for the first representation, the same structures can also be used for the second representation. The area of a Representation can usually be split and structures to form first and second representations can be interleaved (e.g. small stripe or checkerboard shaped areas with dimensions preferably below the resolution of the human eye, ie less than about 100 µm). In addition to nesting, it would also be conceivable to provide such structures in two embossing planes, with at least the upper one being at least semi-transparent, so that the embossing underneath also remains visible.

The second representation, which is preferably visible in plan, can represent either an optically variable or optically non-variable image. If the second representation is optically variable, it can have a curved representation. The second view can also have kinematic effects. It is also possible for the first representation to have such kinematic effects if, for example, it is not only visible from a single viewing angle and/or rotation angle, but in a larger angular range.

The segmentation or division into n segments or picture elements and their rearrangement, which is initially generated digitally, can then be incorporated into and/or onto a substrate and/or applied, for example the digitally generated target representation can be in encrypted form and/or the second representation can be applied to a micromirror array that includes a walking or a 3D effect.

An app that can decode an image taken by the camera in real time can then show an animation when the security feature is tilted or the smartphone is moved back and forth in the corresponding viewing angle range.

In addition to a first sub-area with an encrypted tilting image view, ie an optically variable target representation in encrypted form, a second sub-area can be provided on a security feature, which is not encrypted and also does not necessarily have to have a tilting effect. However, this second partial area can also have optically variable effects. In order to increase security, the first and/or the second partial area can show further optically variable effects. Furthermore, a color-shifting coating can be provided, which covers the first and/or second partial area. These additional effects can also optionally be checked by an app.

7 shows photographic representations of a security feature 1 according to an embodiment. The security feature 1 is integrated into a transfer strip, in particular a foil strip, with a large number of optical effects. The encrypted first sub-area takes up less than a quarter of the area.

7(b) shows a top view of the transfer strip from a first viewing perspective, in which the segments 4a of a first representation 4 can be at least partially recorded and/or viewed. The first representation 4 in 7(b) is a target representation in encrypted form 4b, appearing as an array of unordered segments 4a. The predetermined target representation 4c cannot be recognized in this case. The 7(a) Figure 12 shows a top view of the transfer strip from a second viewing perspective in which a second representation 5 superimposed on the first representation 4 can be detected and/or viewed. The second representation 5, which is superimposed on the first representation 4, depicts the number "50". The display also has a warping effect. The number can, for example, give software an indication of the appropriate decryption code or indicate another information content. Thus, from the first viewing perspective, only the target representation in encrypted form 4b is visible and detectable, and from the second viewing perspective, only the second representation 5 is visible and detectable.

By capturing the first representation 4 with a capturing unit and applying a predetermined matching decoding code, the image of a hedgehog can be formed and mapped as a predetermined target representation 4c. The predetermined target representation in decrypted form 4c can then be compared with a reference representation 12. In the present case, the reference representation 12 shows the hedgehog roughly as it should appear or be depicted in the event of correct verification. The comparison can be done digitally and/or visually by the user.

In addition to the optically variable displays in the display field 3, as in 7 shown, further optically variable representations 5 lie outside of the field of view 3 . 3 botanical ornaments are shown here outside of the viewport, which have 3D effects and color effects to enhance the aesthetics of the transfer strip.

The transfer strip also shows a color shift effect. It comprises, for example, a color-shift effect layer, in particular a color-shifting three-layer structure, which is present, for example, over the entire area or only locally in the display field 3 . The viewport 3 and/or the transfer strip thus appear in 7(a) and (b) different colors such as magenta and green.

In this version, an app for verification can not only display the decrypted image of the hedgehog, but also other effects, such as a color change of the entire transfer strip - for example from magenta to green, as in the 7 shown; and/or it can display and/or image various kinematic effects for verification.

Reference List

1

security feature

2

substrate

3

viewport

4

First presentation

4a

Segments of the first representation

4b

Target representation in encrypted form

4c

Predetermined target representation in decrypted form

5

Second representation

6

viewing perspective

7

registration unit

8th

unit of account

9

decryption system

9'

Smart device

9"

server

10

Item provided with a security feature

11

output unit

12

reference representation

100

System for verifying a with a security feature

200

Procedure for verifying a security feature

210

applying the predetermined decryption key

300

Process for producing a security feature

310

providing a predetermined target representation

320

segmenting the predetermined target representation

330

Generating the first representation

a

viewing angle

β

rotation angle

K

tilt direction

KA

tilt axis

R

direction of rotation

RA

axis of rotation

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• WO 9719821 A1 [0004]
• WO 2014060089 A2 [0004]
• WO 2011066991 A2 [0004]
• DE 102013021806 A1 [0004]

Claims (22)

Security feature (1) for a verification system comprising: an optically variable display field (3) which displays at least a first display (4); wherein the first representation (4) comprises a plurality of segments (4a) which form a predetermined target representation (4c) in encrypted form (4b), wherein the first representation (4) for at least part of the plurality of segments (4a) can be detected from at least one first viewing perspective (6) or at least one first viewing perspective area, and wherein the first representation (4) is adapted to form the predetermined target representation (4c) by applying a predetermined decryption code to the plurality of segments (4a). Security feature (1) according to one of the preceding claims, wherein the display field (3) further comprises at least one second display (5): - wherein the second representation (5) is at least partially optically non-variable and does not overlap with the first representation (4); and or - wherein the second or a further second representation (5) is at least partially optically variable, wherein the first representation (4) preferably at least partially overlaps with the second representation (5), and in particular from at least one second viewing perspective (6) or at least one second viewing perspective area can be detected and wherein the at least one first viewing perspective (6) does not correspond to the at least one second viewing perspective (6) or the at least one first viewing perspective area does not overlap with the at least one second viewing perspective area. Security feature (1) according to claim 1 or 2 , wherein the plurality of segments (4a) of the at least one first representation (4) depicts the predetermined target representation in encrypted form (4b) and/or wherein the first representation (4) is designed, using the predetermined decryption code, to the plurality of Segments (4a) depicting the predetermined target representation (4c). Security feature (1) according to one of the preceding claims, wherein the first viewing perspective (6) represents an axis between a viewing point (BP) on a plane in which the first viewport (3) lies and a position (P) of a viewer or a capturing unit; and or wherein a plane, in particular a substrate plane (E) of a substrate (2), is spanned by a first axis (A1) and a second axis (A2); and or wherein the first viewing perspective (6) is defined by a first rotation angle (α) and a first viewing angle (β); and or the security feature is present on a substrate (2), which is in particular a target substrate, a transfer substrate or a security element substrate. A security feature (1) according to any one of the preceding claims, wherein each segment (4a) of at least a portion of the plurality of segments (4a) each has a microstructure and wherein each microstructure has a plurality of microstructure elements and is designed to block incident light from one of to reflect, focus and/or diffract at least one first viewing perspective (6) or one of the at least one first viewing perspective range and preferably under one of the at least one second viewing perspective (6) or one of the at least one second viewing perspective range. Security feature (1) according to one of the preceding claims, wherein the first representation (4) is designed to, using the predetermined decryption code on the plurality of segments (4a) comprising a mapping code for unique mapping and / or a rotation code for rotating through at least one angle and/or an expansion code for expanding and/or a contraction code for contracting and/or a coloring code for coloring at least part of the plurality of segments (4a), the predetermined target representation (4c) to build. Security feature (1) according to one of the preceding claims, wherein the first representation (4) for different parts of the plurality of segments (4a) can be detected from different first viewing perspectives (6) or first viewing perspective areas and wherein the first representation (4) is designed to do so , using the predetermined decryption key comprising a view direction perspective code on the different parts of the plurality of segments (4a) to form the predetermined target representation (4c). Security feature (1) according to claim 7 , wherein the first viewing perspectives (6) each include first viewing angles (β), wherein the first viewing perspective ranges each include first viewing angle ranges and wherein the viewing perspective code includes a tilt code, wherein the first representation (4) for different parts of the plurality of segments (4a) can be detected under different ones of the first viewing angles (β) or the first viewing angle ranges and wherein the first representation (4) is designed to use the predetermined decryption code comprising the tilting code on the different parts of the plurality of segments (4a) to form the predetermined target representation (4c). Security feature (1) according to claim 7 or 8th , wherein the first viewing perspectives (6) each include first rotation angles (α), wherein the first viewing perspective ranges each include first rotation angle ranges and wherein the viewing perspective code includes a rotation code, wherein the first representation (4) for different parts of the plurality of segments (4a) can be detected at different ones of the first rotation angles (α) or the first rotation angle ranges and wherein the first representation (4) is designed to use the predetermined decryption code comprising the rotation code on the different parts of the plurality of segments (4a) to form the predetermined target representation (4c). System (100) for verifying an object (10) provided with a security feature (1), comprising: the security feature (1) according to one of Claims 1 until 9 ; the object (10) which is provided with the security feature (1); and a decryption system (9) comprising: at least one acquisition unit (7) adapted to acquire the first representation (4); and a computing unit (8) adapted to form the predetermined target representation (4c) using the predetermined decryption code on the segments (4a). system according to claim 10 , wherein the decoding system (9) further comprises an output unit (11) which is designed to output the predetermined target representation (4c). System according to 10 or 11, wherein the decryption system (9) forms a unit and preferably comprises a smart device, in particular a smartphone. system according to claim 10 or 11 , wherein the decryption system (9) comprises: a smart device (9`), which has the detection unit (7); and a server (9"), which has the computing unit (8), the smart device (9') being designed to transmit the captured first representation (4) to the server (9"), and the server (9 ") is designed to transmit the predetermined target representation (4c) in decrypted form to the smart device (9`). Method (200) for verifying one with the security feature (1) according to one of Claims 1 until 9 provided object (10): capturing the first representation (4) under the at least one first viewing perspective (6) or the at least one first viewing perspective area; and applying (210) the predetermined decryption code to the segments (4a) to form the predetermined target representation (4c). procedure according to Claim 14 , further comprising: capturing the second representation (5) under the at least one second viewing perspective (6) or at least one second viewing perspective area. Method according to 14 or 15, further comprising outputting or imaging the predetermined target representation (4c). Method according to one of Claims 14 until 16 , further comprising matching the predetermined target representation (4c) with a reference representation for the predetermined target representation (4c). Computer program product that has machine-readable program instructions for a control unit of a data-processing device, in particular a smart device, which they use to carry out a method according to one of Claims 14 until 17 cause. Method (300) for producing a security feature (1) comprising: providing (310) a predetermined target representation (4c); segmenting (320) the predetermined target representation (4c) into a plurality of segments (4a); generating (330) a first representation (4) by applying an encryption key to the plurality of segments (4a) to form the predetermined target representation in encrypted form (4b); generating a decryption key based on the encryption key; and Creating a display field (3) for the first display (4), so that the first display (4) can be at least partially captured from at least one first viewing perspective (6) or at least one first viewing perspective area. procedure according to claim 19 , further comprising: providing a second representation (5); and further establishing the viewport (3) for the second representation such that the second representation (5) is at least partially under at least one second viewing perspective (6) or at least one second viewing perspective range, the first representation and the second representation being in the viewport ( 3) at least partially overlap and wherein the at least one first viewing perspective (6) does not correspond to the at least one second viewing perspective (6) or the at least one first viewing perspective area does not overlap with the at least one second viewing perspective area. procedure according to claim 19 or 20 wherein generating the first representation (4) by applying an encryption key to the plurality of segments (4a) comprises: uniquely mapping at least a portion of the plurality of segments (4a) according to a mapping encryption key; and/or rotating at least part of the plurality of segments (4a) by at least one angle according to a rotation encryption code; and/or expanding at least part of the plurality of segments (4a) according to an expansion encryption key; and/or contracting at least part of the plurality of segments (4a) according to a contraction encryption key; and/or coloring at least part of the plurality of segments (4a) according to a coloring scrambling code; and wherein generating the decryption key based on the encryption key correspondingly comprises: generating an image code based on the image encryption key; and/or generating a spin code based on the spin encryption code; and/or generating an expansion code based on the expansion encryption code; and/or generating a contraction code based on the contraction encryption code; and/or generating a coloring code based on the coloring encryption code. Method according to one of claims 19 until 21 , wherein the digital generation of the first representation (4) by applying an encryption code to the plurality of segments (4a) comprises: determining different viewing angles (β) and/or rotation angles (α) for different parts of the plurality of segments (4a), so that the different parts of the plurality of segments (4a) will be detectable under different first viewing perspectives or first viewing perspective ranges; wherein transferring the first representation (4) into the display field (3) comprises: introducing and/or applying a microstructure for each segment (4a), wherein each microstructure reflects, focuses and light incident under the respective first viewing perspective or the first viewing perspective area /or bends; and wherein generating the decryption key based on the encryption key comprises generating a skew code and/or a rotation code based on a skew encryption key and/or a rotation encryption key, respectively.

Images