WO2017026924A2

WO2017026924A2 - Method of performing an analog-digital signature in a trusted environment and device for the implementation thereof

Info

Publication number: WO2017026924A2
Application number: PCT/RU2016/000577
Authority: WO
Inventors: Дмитрий Александрович ГЕРТНЕР
Original assignee: Общество С Ограниченной Ответственностью "Лаборатория Эландис"
Priority date: 2015-08-07
Filing date: 2016-08-26
Publication date: 2017-02-16
Also published as: RU2616888C2; RU2015133100A; WO2017026924A3

Abstract

A method of providing a trusted environment for performing an analog-digital signature and a device for the implementation thereof are intended to enhance the security of converting source documents into electronic form. Unlike known prior art, the present method and device do not require that the procedure for signing electronic documents be carried out on special certified computers which provide a trusted environment. A trusted environment should guarantee that a digital signature is created in a secure and tested system comprising hardware and software. A violation of these conditions gives rise to potential threats, for example the substitution of an electronic document, i.e. the user sees one document on the screen, while the hacked system signs a different document using the user's name. In the present invention, a trusted environment is formed in a signing device in the form of a stylus, and any non-certified computer can be used. The trusted environment is provided in the invention by a set of technical solutions. A device for signing documents, in the form of a stylus, comprises a security compartment, containing a microcontroller with a software code, a memory with a digital signature secret key, and also inertia sensors, which are connected to the microcontroller, and a loudspeaker, which is likewise connected to the microcontroller and is provided with a voice synthesis program. A wireless interface is used for communication with a computer. The inertia sensors serve to verify the user's manual signature. The loudspeaker and the voice synthesis program serve to voice the text of an electronic document directly from the trusted environment. This guarantees that verified information enters the trusted environment of the stylus.

Description

Method for performing analog-to-digital signature in

trusted environment and device implementing it

The invention relates to the electronic industry, namely to paperless technologies for document management and can be used to translate the primary documentation of enterprises in electronic form. Known algorithms for electronic digital signature (EDS), allowing you to sign electronic documents with an electronic digital signature using user secret keys and verify the authenticity of electronic digital signatures using public keys. The ownership of the public key to a specific user is verified by digitally signing the trust center in the form of a digital certificate. For each user, a pair of unique keys is generated - secret and public keys of electronic digital signature. The user must keep his secret key secret and use it when signing an electronic document.

The disadvantage of electronic digital signature is the difficulty of creating a trusted environment when signing electronic documents, especially when it comes to information containing legal facts. A trusted environment should ensure that the creation of an electronic digital signature on an electronic document is carried out in a trusted system, including hardware and software. For this, it is necessary to use certified computer and software, with the help of which it is supposed to carry out the procedures for creating an electronic digital signature. At the same time, do not allow the computer to connect to non-certified resources on the public network, do not run non-certified software on the computer, or transfer the computer to the wrong hands. Violation of these conditions creates potential threats: - unauthorized access to the cryptographic capabilities of a token / smart card with non-removable keys using spyware allows you to carry out an attack using remote control tools on your client’s computer, an attack using a remote connection to a USB port (USB-over-IP);

- substitution of a document when transmitting it for signature in a token with non-removable keys. An attack is possible using spyware and / or due to software implementation errors. The user sees one information on the monitor screen, and another is sent for signature.

In fact, you can use a certified computer only for signing electronic documents. Moreover, the user can sign electronic documents only on his certified computer. All this creates serious problems for the widespread use of electronic digital signatures.

The closest analogue is the invention “a method of signing documents with an electronic analogue-digital signature and a device for its implementation” - RF patent N ° 3398334, which allows you to sign documents with an electronic analogue-digital signature, without first generating personal electronic digital signatures of users. The identification of the user who has signed such an electronic document is carried out according to the biometric data of the user, which become an integral part of only this electronic document and which cannot be inserted into another electronic document of a similar format.

The disadvantage of this method and device is the lack of sufficient reliability, which manifests itself in the fact that if an electronic document is entered into a computer device on which software can be preinstalled, which is commonly called hacker, and is able to replace the electronic document displayed on the monitor screen with another electronic document entered into the device for signing. This creates a potential vulnerability that can manifest itself in the fact that the user, against his will, will sign a different electronic document than the one that he sees on the monitor screen. Therefore, in this analogue, documents for signing are not entered from a computer, but from a printed document and additional devices, such as a barcoder, scanner or digital camera, which creates inconvenience in use and the need to pre-print an electronic document.

The objective of the present invention is to provide a method for performing analog-to-digital signature in a trusted environment and a signature device that implements it, which will eliminate this vulnerability and will allow you to safely enter electronic documents directly from any computer into the signature device.

This task is achieved by the fact that the device for signing documents with an electronic analog-to-digital signature in the form of a stylus 1 (Fig. 1) for inputting a handwritten signature consists of a secure compartment 2, in which are located: a microcontroller 3 and an associated memory 4. In the microcontroller 3 there is a program code for data processing and cryptographic operations, in particular algorithms for calculating the checksum and electronic digital signature. Memory 4 contains a secret digital signature key. The public key and, if necessary, a digital signature certificate can be located on external media. Additionally, the stylus 1 includes a transmitter-receiver 5 for wireless communication with an external computer. The transmitter-receiver 5 is connected to the microcontroller 3. The protected compartment 2 contains tamper-evident sensors 6 connected to the microcontroller 3 and the memory 4. In case of violation of the integrity of the protected compartment 2, the secret key is erased in memory 4. The microcontroller 3 associated with the transmitter-receiver 5 for wireless communication with an external computer, it processes data and outputs the processed information through the transmitter-receiver 5 to the computer 7 Thus, a trusted environment is formed inside the device for signing. The main task is to guarantee to the user that the electronic document signed by him has really moved to the trusted environment without changes, and that the handwritten signature of the user also falls into the trusted environment without changes. According to the invention, the device is characterized in that inertial sensors 8 are additionally placed inside the protected compartment 2 to record the inertial characteristics of the stylus, and therefore the handwritten signature. Inertial sensors 8 are connected with the microcontroller 3. As inertial sensors, you can use the accelerometer, gyroscope and magnetometer, made by micromechanical technology. These miniature sensors are able to provide the necessary information about the movement of the stylus - acceleration, speed, direction of movement and tilt angles.

In addition, a sound speaker 9 is placed in the protected compartment 2 and connected to the microcontroller 3. The speech synthesis program is pre-flashed into the microcontroller 3. As the sound speaker 9, you can use a miniature piezodynamic. Since the external part of the sound speaker must be brought out, to prevent opening the case of the signature device at the exit point of the sound speaker, at least one tamper sensor b is connected to the sound speaker 9. For example, if a thin thin conductor is used as the tamper sensor 6, wrapped around the body of the device for signature, this conductor is also passed through the sound speaker 9 or above it. Short current pulses are sent along the conductor in both directions and their magnitude is measured. In the case of a significant change in the pulse value, it is believed that the protective case 2 was opened and the microcontroller 3 is instructed to erase the secret keys.

The method of performing analog-to-digital signature in a trusted environment works as follows. The user sees an electronic document on the monitor screen of the external computer 7. It is verified that a signature device, stylus 1, is connected to computer 7 via a wireless communication channel. Next, the user sets a command to prepare the document for signing through the program interface. After which the electronic document is sent from the computer 7 to the device for Signatures - stylus 1 over a wireless communication channel. An electronic document is loaded into the memory of the device for signature and transmitted to the microcontroller 3, where, using a speech synthesis program, the text of the electronic document is converted into speech in the form of an audio signal. The audio signal is transmitted to the sound speaker 9 and the user can listen to the text of the electronic document directly from the device for signing, that is, from a trusted environment. Thus, the user is guaranteed that the electronic document located in the trusted environment is not modified and corresponds to the original in text form. In addition, this method of familiarization with electronic documents before signing them is convenient if you use devices with a small screen as a computer, such as smartphones.

After the electronic document has been loaded into a trusted environment, the user can sign it using the stylus 1 on the computer screen 7. It is assumed that a screen with the pen input function is used. It can be a tablet computer or a smartphone with a touch screen screen. At the same time, an option is not ruled out in which the user enters his handwritten signature on some external device intended for this purpose. In any case, the handwritten signature input device should receive the digitized handwritten signature roller and send it to the transmitter-receiver 5 of the stylus 1 via the wireless transmitter-receiver, from where it will be placed the trusted medium in the protective compartment 2, namely in the microcontroller 3. At the same time inertial sensors 8 also supply their microcontroller 3 with their data on the movement of the stylus during the input of a handwritten signature. These data are supplied by such sensors as an accelerometer, gyroscope and magnetometer, made by micromechanical technology. With a certain degree of error, the data from inertial sensors and the handwritten signature roller correlate with each other. This relationship, with a predetermined error, using the program code in the microcontroller 3 is used to determine the ownership of the downloaded digitized signature roller data from inertial sensors. Inertial data acquisition time sensors and the time of receiving points of the trajectory of the handwritten signature roller is fixed, therefore, a common timeline is used for their comparison, which simplifies the analysis of the comparison.

Thus, in the case of a positive result of the comparison of the trajectories and other dynamic characteristics of the signature roller, the user receives a guarantee that the handwritten signature roller created by him is unchanged placed in a trusted environment.

After completion of the scoring of the text and in case of a positive result of the comparison of the video clip, the trusted environment is considered secured and cryptographic operations are performed in the microcontroller 3 of digitally overwriting the digitized handwritten signature roller and the digitized electronic document using the secret digital signature key from memory 4.

In particular cases, for the convenience of the user, the invention can be implemented using an additional external audio device 10 (Fig. 2), which is physically separated from the stylus 1. Such an external audio device can be headphones or speakers. The synthesized audio signal from the stylus 1 is relayed to the external audio device 10. The audio signal can be relayed either via a cable or via a wireless interface, in particular, from the transmitter-receiver 5 to the transmitter-receiver 11. The transmitted audio signal is reproduced on the sound speaker 12. In case of application external audio device 10 for transmitting the original audio signal, you must use a trusted channel, in order to prevent the potential threat of relaying to an external audio speaker audio signal. To create a trusted communication channel between the signing device and the external audio device 10, a cryptographic module 13 is placed in it. At the same time, a similar cryptographic module 14 is also included in the signing device, in the main secure compartment 2, the keys are pre-distributed in both cryptographic modules 13 and 14 encryption. It can be either identical symmetric encryption keys or unique asymmetric secret and public keys to provide a common trust environment between both devices through interaction using the specified cryptographic modules and keys.

In another embodiment of creating a trusted communication channel between the device for signing 1 and the external audio device 10, indicators 15 and 16 are placed on both devices from the outside to visually display the current parameters of the audio signal. For example, multi-colored LEDs or liquid crystal indicators. The indicators 15 and 16 can be configured to display parameters such as the amplitude of the sound on several frequency channels. If multi-colored LEDs are used as indicators, then when pronouncing various sounds generated by the speech synthesizer, different LEDs should be lit in different combinations and with different brightness. If the audio signal is relayed unchanged, then on both devices — stylus 1 (signature device) and external audio device 10, the LEDs should light up synchronously and equally, since they visualize the same audio signal and almost at the same time. In the same way, when using liquid crystal indicators, oscillograms corresponding to the sound parameters of the relayed and outputted audio signal should be displayed synchronously and equally on them. Thus, the user will be able by ear and by eye to verify that the audio signal is transmitted from device to device without changes.

In addition to voicing the texts of electronic documents, the speech synthesizer in the signature device can also be used to voice the results of data processing or the need for the user to perform certain critical actions.

In general, the invention can be put into practice using well-known technologies and cryptographic algorithms, in particular digital signature and asymmetric encryption algorithms using elliptic functions. Although the present invention has been described by way of example of some embodiments thereof, those skilled in the art may propose other such embodiments, not going beyond the essence and scope of the invention. Therefore, the invention should be evaluated in terms of the claims.

Claims

Claim

1. A method for performing analog-to-digital signature of electronic documents in a trusted environment using a stylus-type signature device, comprising: a secure compartment in which at least one microcontroller with program code for processing data and performing cryptographic operations is located and associated with a memory with a secret digital signature key, and the protected compartment is configured to erase the secret key in case of violation of the integrity of the enclosure of the protected compartment,

a transmitter-receiver connected to the microcontroller for wireless communication with an external computer,

characterized in that:

at the production stage:

- additionally, inertial sensors are placed in the protected compartment to record the inertial characteristics of the handwritten signature and connect them to the microcontroller,

- additionally, a sound speaker is placed in the protected compartment and connected to the microcontroller with program code with speech synthesis function,

in the process of signing an electronic document:

- receive from the computer via a wireless transmitter-receiver information containing the digitized text of an electronic document and transmit it to the microcontroller,

- in the microcontroller using the program code, the text is read out by converting it into a speech audio signal and the synthesized audio signal is output to the sound speaker,

- receive data on the motion of the stylus from inertial sensors and transmit them to the microcontroller,

- receive information from a computer through a wireless transmitter-receiver, containing the digitized video of the handwritten signature of the user and then transfer it to the microcontroller,

- in the microcontroller, using the program code, the handwritten signature roller is compared with the data transmitted to the microcontroller by inertial sensors and it is determined whether the data from the inertial sensors match the digitized signature roller,

- in the case of a positive result of the comparison and after the completion of scoring of the text, they consider the trusted environment to be secured and perform cryptographic operations in the microcontroller to digitally sign the digitized handwritten signature roller and the digitized electronic document using the secret digital signature key,

- return the result in the form of a digital signature to the computer via a wireless transmitter-receiver.

2. The method according to p. 1, characterized in that the synthesized audio signal is relayed to an external sound speaker via a trusted communication channel.

3. The method according to p. 2, characterized in that the trusted communication channel is provided by encrypting the communication channel using pre-distributed encryption keys in the signature device and on the external sound speaker.

4. The method according to p. 2, characterized in that the trusted communication channel is provided due to the synchronous visual display of the current parameters of the audio signal on the signature device and on the external sound speaker.

5. A device for performing analog-to-digital signature of electronic documents in a trusted environment using a device for signature in the form of a stylus, containing:

protected compartment containing tamper sensors, in which there is at least one microcontroller with program code for processing data and performing cryptographic operations and associated memory with secret a digital signature key, wherein the protected compartment is configured to erase the secret key in the event of tampering sensors in case of violation of the integrity of the enclosure of the protected compartment,

characterized in that the protected compartment further includes:

-inertial sensors for recording the movements of the stylus and associated with the microcontroller,

- a sound speaker connected to the microcontroller to perform the function of speech synthesis.

6. The device according to p. 5, characterized in that at least one tamper sensor is connected to the sound speaker configured to prevent opening of the body of the device for signature at the exit point of the sound speaker.