The authentication method of the object

 

The invention relates to the field of authentication of objects. The technical result is to increase protection against unauthorized use of network services. In this way, using the identification module (e.g., SIM card) external device is the creation of a query that contains a random number and the cryptogram obtained by processing the random number algorithm 2 using the secret key 2, the transfer request to the identification module, checking identification module cryptogram random numbers, the formation of the identification module response by encrypting the query using algorithm 1 and the random number is 1, the response is returned to the external device, comparing the external device, the received response result of an external device encryption query using algorithm 1 and the secret key 1. 3 C.p. f-crystals, 2 Il.

The invention relates to the field of authentication of objects and can be used, for example, for authentication of the mobile terminal (phone) subscriber in the network using an identification module, for example, by using personal smart cards (cards with stroie person).

In telecommunication systems GSM (Global System for Mobile communication) authentication of the subscriber in the network is performed by a known procedure (GSM 11.11) as follows. The network sends a Query (random number RAND) to the mobile terminal (MT). MT sends a request to the SIM card using the command RUN GSM ALGORITHM. SIM card encrypts a random number with a secret key Kistored in the SIM card memory, algorithm A3 and retrieves the value of SRES (Answer), through which MT is transmitted to the network.

SRES=ENC (Ki, RAND), where SRES is the result of the encryption length 4 bytes, ENC - encryption process, Toi- the secret key length of 16 bytes, RAND is a random number with a length of 16 bytes.

The same procedure encryption of the same random number RAND (on the same key using the same encryption algorithm) is performed on the network to retrieve the value of RES. In the case of coincidence of the SRES received from the MT, and RES, calculated in the network, the authentication procedure is successfully completed. The subscriber is allowed to use network services. Authentication of this kind is called internal.

The disadvantage of this solution is in principle possible matching secret key Kiby repeated (several tens of sludge is key Toiby examining the results of the command RUN GSM ALGORITHM (Reply) with the help of special algorithms. Determine the secret key is creating duplicate (clone) card, which gives the possibility of unauthorized use of network services.

Known methods using authentications counter that limits the number of times of selection of the key Toi(SIM SCAN v/1/21 (Aug. 8 2001). Web: http: // www net.yu/~dejan). After execution of each procedure of the authentication counter value is decremented by one and the count makes the card unusable. Thus limited the number of possible execution command RUN GSM ALGORITHM, and hence the resulting steam is Request-Response, used for matching secret key. A typical initial value of the counter authentication is 100,000. However, the development of computers and improved algorithms selection key result of the selection key (40-60) thousand attempts. Further limitation of the initial value of the counter authentication inconvenience as network subscriber (small lifetime of the card) and network operator (card replacement or update the content of the counter authentication).

The essence of external authentication is as follows. Map outputs to an external device (e.g. terminal) random number to the terminal encrypts on a known map of the key. The result of the encryption is returned to the map, which compares it with the result of the encryption of the received inside the map. If both results are the same, the external authentication is considered successful. After you perform an external authentication card is "confident" that works with a legal device. Then the routine is executing internal authentication, i.e., now the map confirms its "legitimacy" to the external device.

In Fig. 1 presents the algorithm processing Request to the identification module.

In Fig. 2 presents the algorithm of the query in an external device.

The technical result, which is aimed invention is to improve the protection against unauthorized use of network services. The technical result is achieved due to the fact that the method of identification of the object, using an identification module, is made, for example, in the form of a SIM card, an external device by the formation of the Query is tion of the number of algorithm 2 using the secret key 2; request identification module; check identification module cryptogram random numbers with lock identification module when the number of requests with incorrect cryptogram exceeds a predetermined number, e.g. 3, the formation Response identification module by encrypting the Query using algorithm 1 and the secret key 1; return Response to the external device; comparing the external device received the Response identification module with the result, carried out by the external device encryption Query using algorithm 1 and the secret key 1.

The proposed solution works as follows. The network generates a random number RAND length of 16 bytes, the last 4 bytes of random numbers are replaced with (FF FF FF FF)hexthen the resulting number is processed according to a certain algorithm 2 (for example. DES, 3-DES, A3) on a secret key 2. The first 4 bytes of the result of processing (cryptogram) replace the last 4 bytes of random numbers. The result length of 16 bytes is the query that is passed to the SIM card of the mobile terminal with the command RUN GSM ALGORITHM. SIM card vechicle which consists of the last 4 bytes (cryptogram). Then the last 4 bytes of the query are replaced by (FF FF FF FF)hexand the result processing using algorithm 2 and the secret key 2. The first 4 bytes of the processing are compared with the stored 4 bytes of the cryptogram. In the case of the cryptogram received from the network and computed inside the map test is performed successfully, then the formation of the Answer. Generating a Response identification module is implemented by encrypting the Query using algorithm 1 (for example, DES, 3-DES, A3) and a secret key 1. You then return the Response to the external device, comparing the external device received the Response identification module with the result, carried out by the external device encryption Query using algorithm 1 and the secret key 1.

To exclude the possibility of selection of the cryptogram random numbers by repeated submission to map the random number with the wrong cryptogram, the operating system maps can be embedded counter incorrect presentation of the cryptogram. The counter works the same way as the counter of incorrect filing PIN. i.e. after a limited number (e.g. the proposed technical solution is impossible to obtain a sufficiently large number of pairs of Query-Response consequently, to start the procedure of selection of the key is not giving the map the correct cryptogram Request. The matching cryptogram is excluded by the presence of the counter of incorrect presentation of the cryptogram.

The proposed solution does not exclude the possibility of interception request cryptogram and Answer cards (for example, by intercepting the communication Protocol with the card by attaching directly to the contact pads of the card during real work in the network and therefore allows after a large enough (tens of thousands) sample Request-Response matching keys used to compute the cryptogram, and to generate a Response.

It should be noted that in this case, the frequency of the procedure Request-Reply is set to the network itself, not the program selection key, therefore, to obtain a really necessary values sample Request-Response may take several years (the average number of authentications per day in the real network is 10-50, therefore, to obtain 65 000 pairs of Request-Response will need to intercept information for 65000: 50 authentications/day=13000 DN.:DN.=3.5 years).

It should also be noted that use is of the cryptogram using the same key, which is used for authentication, does not require alteration of the mobile terminal, and causes only relatively small changes to the software network (Center Authentications) and, of course, changes in the operating system of the SIM card.

Claims

1. The authentication method of an object external device using the identification module, is made, for example, in the form of a SIM card, which consists in forming an external device request in the form of a random number, transmitting a request to the identification module, the formation of the identification module response by encrypting the received request using algorithm 1 using the secret key 1, the response is returned to the external device, comparing the external device received the response identification module with the result of an external device encryption query using algorithm 1 and the secret key 1, characterized in that formed an external device, the request contains the random number as a maximum, complete the cryptogram obtained by encrypting the random number algorithm 2 using the secret key 2 2. The method according to p. 1, wherein the query is a random number whose part substituted by the length of the part of the cryptogram.

3. The method according to any of paragraphs.1 and 2, characterized in that the encryption algorithm 2 is identical to algorithm 1, and the secret key 2 identical secret key 1.

4. The method according to any of paragraphs.1 to 3, characterized in that the identification module includes a count of requests that contain invalid cryptogram, and in the case that the number of requests containing invalid cryptogram, and in the case that the number of requests with the wrong cryptogram preassigned values the work of the identification module is blocked.

 

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2 dwg

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