SI9400439A - Process and device for secure an information data packet - Google Patents

Abstract

In a method for saving the information of a data packet comprising a number of data words (W1 ... We) during the transmission between a transmitting device (2S) and a receiving device (2E), the uncoded data packet is supplemented in a first transformation block (17) by means of a data word (CC) which exhibits a bit pattern which is used uniquely for saving within a predetermined time interval. A supplemented data packet (W1 ...f) is sequentially coded in units of identical length in a device (19) using the cipher-feedback method, the first data word (W1) to be coded being transformed into a unique data word (W1<*>) in a second transformation block (18) before being coded and a coded data word (Yk) being generated by a nonlinear combination of coded data words in the device (19). <IMAGE>

Description

Procedure and preparation for securing data packet information

The invention relates to a method for protecting information of a data packet as well as to preparing for carrying out the process according to the introductory parts of claims 1 and 6.

Such procedures are used with priority in the transmission of data packets in a data network in which the power network is used as a transmission medium, which is also referred to as Power Line Carrier Datanetwork.

By protecting information when transferring data packets over a portable medium that is easily used by third parties, the information is protected against unwanted reading and interpretation by third parties. Furthermore, security with the receiver enables authentication of information so that the receiver can recognize a data packet that has been duplicated by third parties.

The preparation for coding and / or preparation is known. decoding data streams (US 4 543 646) using the Data Encryption Standard (DES; Federal Information Processing Standards Publication, No. 46), which presupposes structuring data streams into 64 bit units and is technically very demanding.

For encoding data streams that are structured into small bit units or. data words, the Cipher-Feedback-System is known (D.W. Davies and W.L. Witnesses, Security for Computer Networks, John Wiley and Sons Ltd, New York 1984).

It is an object of the invention to provide a process which can be carried out by inexpensive means, to protect the information of a data packet, and to provide a device that operates by this process.

The present invention is solved by the features of claim 1 and claim 6. Preferred embodiments arise from dependent claims.

Hereinafter, embodiments of the invention are explained in greater detail by way of drawing.

In this, FIG. 1 is a user station with a device for protecting data packet information; FIG. 2 is a telecommunications network with multiple instances of a user station, FIG. 3 is a data flow diagram for a process for securing information of a data packet; FIG. 4 is a preparation for encoding a data packet and FIG. 5 preparing to decode the data packet.

In FIG. 1 is a number 1 user station which is designed as a transmitter and receiver device and has at least one device 2 for securing information of the data packets, at least one port 3 for the transmission means, which in FIG. 1 is not represented, the input module 4 connected to the input terminal 3 on the input side and the output module 5 connected to the output 3 terminal on the output side.

The data packet information security device 2 comprises a first data input 6 for a first data stream 7 with unsecured information, a first data output 8 for a second data stream 9 leading to an output module 5, a secured information, a second data input 10 for a third data stream 11 emitted by input module 4, with secured information, and a second data output 12 for the fourth data stream 13 with unsecured information.

Further, device 2 for securing information of the data packet comprises a charging unit 14 with stored key Z, a first transformation chain 15 lying between the first data stream 7 and a second data stream 9, and a second transformation chain 16 lying between the third data stream 11 and fourth data stream 13.

The first transformation chain 15 has a first transformation block 17, a second transformation block 18, and a device 19 for encoding the data packets arranged one after the other in a sequence of enumeration, the fifth data stream 20 being transmitted between the first transformation block 17 and the second transformation block 18, and further a sixth data stream 21 between the second transformation block 18 and the encoder 19 for encoding the data packets.

The second transformation chain 16 comprises a data packet decoding device 22, a third transformation block 23 and a fourth transformation block 24, which are interconnected in a chain in the order of their indication, wherein the seventh data stream 25 may be transmitted between the data packet decoding device 22 and the third transformation block, and further the eighth data stream 26 between the third transformation block 23 and the fourth transformation block 24.

Thus, the device 19 and the device 22 for encoding or. the decoding of the data packets is connected to the memory unit 14 so that the Z key can be read with both devices 19 and 22.

FIG. 2 shows telecommunication network 30 with three instances of user station 1. The maximum number of instances of user station 1 in telecommunication network 30 is essentially unlimited. The existing electricity distribution network, the so-called electricity network - can be advantageously used as a transmission medium of the telecommunications network 30.

The first embodiment 1.1, the second embodiment 1.2 and the third embodiment 1.3 of user station 1 are each connected to the telecommunication network transmission port 30 via port 3. The third embodiment 1.3 is a variant embodiment comprising two instances of device 2 (FIG. 1) for securing the data packet, as well as two instances of input module 4 and output module 5, the second instance of device 2 for securing the data packet via a second instance of the output module 4 and via a further instance 3.1.

The fourth embodiment 1.4 of user station 1 is connected to the third embodiment 1.3 by means of the portable device 31, wherein the portable device 31 is connected at the port 3 of the fourth embodiment 1.4 and at the port 3.1 of the third embodiment 1.3.

The portable device 31 is e.g. telephone network.

In a telecommunications network 30 or via a transmission device 31, e.g. transmit a control command and / or measurement values between embodiments 1.1, 1.2, 1.3 and 1.4 of user station 1, which are configured as transmitting and receiving apparatus, wherein the transmitted information - e.g. control command or measurement values - Prior to delivery, securely secured in device 2 (Fig. 1) of embodiment 1.1, 1.2, 1.3 or 1.4, which acts as a transmitter, and is retrieved after transmission in preparation of embodiment 2 1.1.1.2 , 1.3 or 1.4 acting as a receiver.

The first data stream 7 (Fig. 1) is formed from data packets W, which in number consist of e equally long data words W ₁ - \ V _e with word length L. If user station 1 acts as a transmitter, the first transformation chain 15 the information of the first data stream 7 is secured by packets, the second data stream 9 comprising the secured information being formed from data packets _p which in number comprise f equally long data words Y ₁ -Y _f with word length L. By means of an output module the second data stream 9 is transmitted to user station 1, which acts as a receiver, with the output module 5 performing the functions necessary for transmission, such as e.g. adapting to the transmission channel, modulating and controlling the connection.

In user station 1, which acts as a receiver, the transmitted third data stream 11 is available on the output side of the input module 4, which performs the functions necessary for receiving data, such as. adapting to the transmission channel, demodulating and filtering. The received third data stream 11 is formed from data packets comprising, by number, f equally long data meshes Yj-Y _f with word length L. In user station 1, which acts as a receiver, information is retrieved by means of another transformation chain 16, which is secured contained in the third data stream 11.

A preferred procedure for protecting data packet information is presented in FIG. 3, which also shows the retrieval of information. The label 2 _g denotes the device 2 (Fig. 1) of user station 1 acting as a transmitter, while the label 2 _E indicates the device 2 of user station 1 acting as receiver. The 2 _S and 2 _{β devices} , which are separated from each other by the telecommunication system 32, generally belong to different embodiments 1.1, 1.2, 1.3 and 1.4 (Fig. 2) of user station 1.

If, for example, the method uses when transferring the data packet from the third embodiment 1.3 to the first embodiment 1.1, the telecommunication system 32 comprises at least the output module 5 and the port 3 of the third embodiment 1.3, the transmission medium of the telecommunications network 30 as well as the port 3 and the input module 4 of the first embodiment 1.1 .

Preparation 2 _S comprises data memory 33 for preparing a second data stream 9 from the first data stream 7, while preparation 2 _E comprises a further data memory 34 for retrieving secured information from the third data stream 11.

In the first step of the process, it is ensured that a data packet comprising data words W -W comprises, at a predetermined location, a data word having a bit pattern once used at a predetermined time interval T at said security position, thereby a one-time time packet in the time interval T. The first step of the process is preferably performed with the first transformation block 17 by supplementing the data packet W _{1 e} created from data words W -W with a further data word CC of word length L, thus to create a data packet W _{1 f} comprising data words W ₁ -W _p wherein f = e + l and preferentially adding the data word CC at the end of the data packet W _x , such that the data word is used to achieve higher data security packets W _x relatively late encodes. The CC data word is constructed in such a way that it forms a high probability session only once in a time interval T, e.g. lasts for several days. The preferred construction of the CC data word is achieved if the CC data word is calculated by transforming T _cc from at least parts of the date and time of its generation.

In the second step of the process, the second data word W to be encoded of the extended data packet W with transformation T _w , which can be performed with the second transformation block 18, is transformed into data word W ₁ 'such that the first data words W to be encoded in the two extended data packets W _{f are} different from each other if two W _x data packets, each of which are identical to the first first data word W, appear in security for transmission at time interval T. Transformation T _{w of the} second data step is preferably an anti-valence operation of the data word W _p to be encoded as the first data word, with the data word CC, using the anti-valence operation in both data words W and CC each time on equivalent bits and with the first data overwrites the word W _x with the result W * of the said anti-valence operation. Anti-valence surgery is also referred to in digital technology as a logic-exclusive OR function. as XOR. As a rule, the anti-valence operation for data words in the microprocessor is directly available as a machine command.

In a record similar to the PASCAL programming language, in which the anti-valence operation is indicated by the © symbol, the preferred embodiment of the second step of the procedure is written as follows:

{T _w (W ₁ ):} © CC [Fl]

If the word length L is e.g. four bits and the CC data word has a binary value 1010, while the first data word W ₁ has a binary value 1001 before the second process step, then the first data word W _x * has a binary value 0011 according to a preferred embodiment of the second process step.

In the third step of the process, the updated data packet W _{x (} coded using the Cipher-Feedback procedure known in itself, using the key Z and first encoding the data word W 'is preferred. Preferably, the completed data packet W _f encodes with the encoder 19 for encoding the data packet, creating a second data stream 9 with protected information that can be transmitted from the communication system 32 to the device 2 _E , where it is available as a third data stream for retrieving the secured information.

By converting the first data word W to be encoded into a data word W 'by transformation T _w before encoding, the CipherFeedback process preferentially generates different encrypted words if it has multiple data packets to be encoded. to protect, in each case, identical to the first data word W, which increases the security of the transmission information.

In order to retrieve the protected information, it is preferable to carry out two steps, which are essentially determined by the information security procedure presented.

In the first step, the encoded extended data packet Y is decoded using the Cipher-Feedback procedure, using the Z key again. The first step is preferably performed by preparing the 22 for decoding the data packet, creating a seventh data stream 25 in which an extended data packet W _{1 f is available} with the exception of the first data word W * as a clean copy - that is, with non-encoded information.

In the second step, the first data word is W *, which is preferably done by reusing the transformation T _w .

Using the CC data word and the anti-valence operation, denoted by φ, the second step is:

{T _w (w;):} W _i: = W / Φ CC. [F2]

Preferably, the second step is performed with the third transformation block 23.

Since the transformation T _w to V is an antivalence operation with CC, the first data word W _p to be encoded is transformed into a data word W ₁ * such that the first data words W 'to be encoded are v the two extended W _xf data packets are different from each other if two data packets W _t having the same first data word W _p are received for transmission during the time interval T and the data word W can be received in the receiving preparation using transformation T _w on W 'can regain with a little effort.

In a second step, the information provided in a secure form by the communication system 32 is available as a clean copy in the data packet W of the eighth data stream 26, and the data packet W _f also includes a data word CC that can be used for authentication.

Preferably, the authenticity of the data packet W comprising the data words W -W is determined by the fourth transformation block 24 by explaining the data word CC.

In the receive preparation, the W _x data packet comprising the W _x W data words is preferably received only if the data word CC supplementing the W data packet has a predetermined value range. If the receiving device is e.g.

part of the electrical meter or tariff preparation and the received W _xe data packet comprises the command to switch from high tariff to low tariff, it may be advantageous to identify, by analyzing the value range of the CC data word, whether the W _{2 e} data packet _is authentic or possibly third parties duplicated.

In FIG. 4, a preferred embodiment of a Cipher-Feedback encoder 19 for encoding a data packet has an m-step scroll register 35, with which m coded data words Y _k -Y are available to generate a coded data word Y _k for the data word W _k , with index k being the index range from 1 to f. With the scroll register 35, the coded data word Y _k -Y _{k +1} can be scrolled through the data words each time before the coded data word Y _{k + r is} formed _.

The coded data word Y _k is the result of the operation W _R ®T _k , where the sign φ denotes an anti-valence operation performed on the data word W and is a data word T _{k of a} data length L and is an operation W _k φ T _R for encoding the data word W _f must be derived for each index value in the index range 1 through f. The data word T _k is the functional value of the nonlinear connection F _{R of the} coded data words Y _k j to Y _R :

· [F3]

In FIG. 5, a preferred embodiment of Cipher-Feedback decoder 22 for decoding a data packet comprises an m-step scroll register 36, by which m coded data words Y _{fc l} to Y are available for decoding the coded data word Y _R. Scroll register 36 encodes the data words Y _k through Y _k . _{m + 1} moveable by data words each time before decoding the data word Y _{k + r}

The non-encoded data word W is the result of the operation Y _k φ T, where the sign φ represents an anti-valence operation performed on the data word Y _k and is a data word T _{R of} word length L and the operation Y _R φ T _k to decode the data word Y must perform for each value of k in the index range from 1 to f. The data word T _k is the functional value of the nonlinear connection F _{R of the} coded data words Y _{R 4} to Y _{R m} .

In a preferred way, the nonlinear connection F _{k is} realized by antivalence operation between sums, the sum being formed from a random number and at least one coded data word Y _kl or. Y _{k 2} oz. Y _k .

The Z key used in the Cipher Feedback process has p components, with p being also denoted as the key length. In fact, by increasing the number of p - that is, by increasing the length of the key - greater security can be achieved.

The following is a preferred definition of a nonlinear connection F _k , with the two shift registers 35 and 36 being three-tier and having the key Z having six components; therefore, p = 6.

The aforementioned link F _k is preferably preferred for implementation in an 8-bit microcomputer if the word length L of the data words W ₁ -W _{f of the} data packet W _f is also 8 bits. Both shift registers 35 and 36 are preferably implemented by a code executed by the microcomputer.

From the key Z = (Z _p Z ₂ , Z ₃ , Z ₄ , Z ₅ , Z ₆ ), whose six components Zj to Z ₆ are integers in the range 0 to 255, it is calculated:

the first value c ₄ with an integer value range [0 ... 1] having the highest valence bit value (the most important bit of MSB) of the fourth key of component Z ₄ , the second value c ₅ with an integer value range [0 ... lj which has the highest valence bit value (the most important MSB bit) of the fifth key of component Z ₅ , the third c ₆ value with an integer value range [0 ... 1] that has the highest valence bit value (the most important MSB bit) of the sixth key of component Z ₆ , the fourth value of b ₄ with an integer value range [0 ... 127] having the fourth key value of component Z ₄ without a bit (MSB) with the highest valence, the fifth value of b ₅ with an integer value range [0 ... 127], having the value of the fifth key of component Z ₅ without bit (MSB) with the highest valence, the sixth value of b ₆ with an integer value range [0 ... 127] that irritates the sixth key component of Z ₆ without bit (MSB) with the highest valence , the first BI coefficient of the formula

Bl: = 2 * b ₄ + 1, [F4j second coefficient B2 of formula B2: = 2 * b ₅ + 1, [F5j the third coefficient B3 according to the formula B3: = 2 * b ₆ + 1, [F6j the first initial value of Υθ by the formula Y ₀ : = 131 + c ₄ , [F7j the second initial value Y j according to the formula Y _i: = ll + c ₅ , [F8j the third initial value Υ _n of formula Y. ₂ : = 67 + c ₆ , [F9] the fourth initial value of R1 _Q by the formula Rl ₀ : = Z _p [F10] the fifth initial value of R2 _fl by the formula R2 ₀ : = _Zl [Fllj and the sixth initial value of R3 ₀ according to the formula R3 ₀ : = Z ₃ . [F12]

With the first constant Al = 65, the second constant A2 = 5, and the third constant A3 = 33 se. calculate each index value k in the index range 1 through f as follows:

the first random number Rl _k limited to eight bits by the first random number generator according to the formula

Rl _k : = [Al * Rl _k . _{1 +} Bl] _mod256I [F13] a second random number R2 _k limited to eight bits by a second random number generator according to the formula

R2 _lt : = [A2 * R2 _k . _I + B2] _mod2J6 , [F14] third random number R3 _k limited to eight bits by the third random number generator according to if (k mod 251) not_equal 1 then

R3 _k : = [A3 * R3 _kl + B3] _mod256 else

R3 _t : = [A3 * R3 _{0 +} B3] _mod256 end if [F15] and a finite nonlinear connection F _k limited to eight bits by the formula F _k : - [Rl _k + T _kl ] _power 25g © [R2 _k + Y _kl + Y _k . ₂ ] _mod256 + [ΪΤ6]

The advantageous transformation F _R uses three generators Rl _k , R2 _k and R3 _{k of} random numbers acting according to the formulas [F13] or. [F14] respectively. [F15] so calculated that the smallest common multiple of all periods is as large as possible.

If necessary, the preferential transformation F _k can be extended by further random number generators.

The high security of the information in the encoded data package Y _f is mainly achieved by combining three steps of the process that can be performed by preparation 2 (Fig. 1), namely that

1) the data packet W is completed with the data word CC and further

2) change the first data word W _p to be coded by transforming T _w by the formula [Fl] and that

3) the data word T _fc is used in the Cipher Feedback process, which is formed by the nonlinear transformation F _k from the coded data words Y _k to Y _k . _{m + r}

The procedure described above for protecting data packet information is, above all, efficiently illustrated by the formulas [Fl] and [F16], feasible with inexpensive microprocessors or microcomputers, e.g. with Motorola's MC68HC11. The process can also be advantageously used in telecommunications networks with unreliable transmission channels, because the use of the expanding CC data word in conjunction with the transformation T _{w of the} first data word W to be encoded into the data word W _x * may require complex synchronization of algorithms for coding or. decoding.

Claims (6)

PATENT APPLICATIONS 1. A method for protecting information of a data packet (WJ comprising several data words when transferring between a transmitting device (1; 2J connected to a transmission means) and a receiving device (1; 2 _E ) connected to a transmitting means , wherein the non-encoded information of the data packet (Wj) is encoded using the Cipher-Feedbach process in the broadcast device (1; 2 _§ ) and the encoded information is decoded in the receiving device (1; 2 _E ), characterized in that it is uncoded the data packet (W) is expanded at a predetermined location by a data word (CC) having a bit pattern that is used once at a predetermined time interval (T) at the security location, thereby forming a unique one at a time interval (T). an expanded data packet (W) that the completed data packet (W _f ) is sequentially encoded or decoded in equally long units using the Cipher-Feedback process, each time being one unit being one data word (W; Y), and that the first data word (W ) to be encoded, transforms the extended data packet (W _f ) so that the first data words (W) to be encoded in the two completed data packets (W _f ) are different from each other if viewed two data packets (WJ having identical identical first data words (W)) are matched to the transmitter (1; 2J at time interval (T)). A method according to claim 1, characterized in that the encoded data word (YJ is formed by the anti-valence operation of the non-encoded data word (WJ and further data words (TJ, where a further data word (TJ is formed by a nonlinear connection (FJ of a certain number (m) coded data words (Y _k4 , Υ., .-, Υ.). Method according to claim 2, characterized in that it is a nonlinear connection (FJ is performed by anti-valence operations between sums, the sum being formed from a random number (Rl _k ; R2 _k ; R3 J and at least one coded data word (Y _kl ; Y _k . ₂ 5 - \. M) · Method according to one of the preceding claims, characterized in that the once used data word pattern (CC), which complements the data packet (W), is formed from the current date and time. Method according to one of the preceding claims, characterized in that the first data word (WJ to be encoded) is modified in the broadcast by modifying the anti-valence operation with the data word (CC) supplementing the data packet 6. A device for protecting information of a data packet (Wj) comprising several data words during transmission between a transmitting device (1; 2J connected to a portable means and a receiving device (1; 2 _£ ) connected to a portable device means encoding the non-encoded information using a Cipher-Feedback process in the transmitter (1; 2 _S ) and decoding the encoded information in the receiving device (1; 2 _E ), characterized in that the memory unit (14) comprises a key (Z) and providing the memory (33) contained in the transformation chain (15) with the first transformation block (17) in front of the second transformation block (18) and with a device (19) connected behind the second transformation block (18), and is coupled to a memory unit (14) for encoding data packets using a key (Z), wherein the data packet (W) can be supplemented with a first data block (17) for a data word (CC) having a bit pattern that is used once at a predetermined time the security interval (T), and that the first data word (W) to be encoded of the data packet (W) is variable with the second transformation block (18) by means of an anti-valence operation with the data word (CC) supplementing data packet (W), and a Cipher-Feedback process can be performed by preparation (19).