KR100321716B1 - Key authentication method in authentication system - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a key authentication method in an authentication system and a computer-readable recording medium having recorded thereon a program for realizing the method.

2. The technical problem to be solved by the invention

The present invention, in the wireless communication authentication system, such as CT-2, to compensate for the security problems caused by the authentication performed in the base station does not have a secret key of the terminal, to prevent illegal use of the service by using a random number To provide a key authentication method and a computer-readable recording medium recording a program for realizing the method.

3. Summary of Solution to Invention

The present invention provides a key authentication method in a wireless communication authentication system, comprising: a first step of a subscriber management apparatus transmitting an encrypted random key generation key and a key generation function number to a base station; A second step of decrypting, at the base station, a key generation function by decrypting a key generation random number and a key generation function number received from the subscriber management apparatus; The terminal receives a random key generation number from the base station and performs authentication with the base station using a key generation random number and a key generation function number, and determines whether to update the secret key of the terminal through the authentication result at the base station during the authentication procedure. A third step of requesting the subscriber management device to update the secret key of the terminal; And a fourth step of generating, by the subscriber management apparatus, a secret key using a random key generation key and transmitting the secret key to the terminal together with a key generation function number according to a key update request of the base station.

4. Important uses of the invention

The present invention is used in wireless communication authentication system.

Description

Key authentication method in authentication system

The present invention, in a wireless communication authentication system such as cordless telephone 2nd generation (CT-2), by complementing the security problems caused by the authentication performed in the state that the base station does not have a secret key of the terminal, service illegal A key authentication method for preventing use and a computer readable recording medium having recorded thereon a program for realizing the method.

CT-2 is a digital transmission-only mobile communication system.

CT-2 service is mainly provided in Asia such as Taiwan, Malaysia, Singapore, Thailand, etc., and is currently under the name of "City Phone" in Korea. The CT-2 provides an authentication function for preventing the toll fraud of illegal users.

The encryption mechanism adopted for authentication in most mobile communication systems is a secret key method that verifies the authenticity of the secret key shared between the terminal and the network.

However, CT-2 also uses a secret key method, but is different from a general mobile communication system in that a terminal and a network do not share a secret key.

Therefore, the CT-2 authentication procedure performed under the non-shared secret key has a security vulnerability. In other words, CT-2 does not have a terminal's secret key (KEY) at the time of performing authentication and generates a secret key from authentication data sent from the terminal.

The authentication data used to generate the secret key of the CT-2 is transmitted to the security intruders as it is transmitted unencrypted. If the security attacker knows the key generation function, the secret key is obtained from the authentication data obtained over the air. You can try to create illegal currency. Due to the weakness of the CT-2 authentication method, illegal use of the service due to the leakage of the key generation function causes a great loss for subscribers and operators.

As such, it is necessary to change the key generation function in order to reduce the damage caused by the leakage of the key generation function. In other words, if the key generation function is changed, the leaked key generation function is no longer useful. Therefore, by changing the key generation function periodically or as often as necessary, the usage period of the leaked key generation function can be reduced.

Therefore, if the usage period of the leaked key generation function is reduced, the meaning of the effort of obtaining the key generation function by the security breachers is halved. Therefore, the update of the key generation function is the key that is the biggest security vulnerability of the CT-2 authentication method. This is a very important security measure that can prevent damage caused by the leakage of the generated function.

However, the CT-2 system currently in service in Korea does not have the function of updating the key generation function and the terminal secret key updating function.

Therefore, in order for the CT-2 system operator to update the key generation function when necessary, the subscriber management apparatus (in this embodiment, a device for storing and managing the profile of the entire subscriber and generating a secret key necessary for registration and re-registration). And a function for this should be implemented in the base station, and for this purpose, a method for efficiently updating a key generation function and a corresponding secret key of the terminal is required.

The present invention has been proposed to meet the above requirements, in a wireless communication authentication system such as CT-2, to compensate for the security problems due to the authentication performed in the base station does not have a secret key of the terminal It is an object of the present invention to provide a computer-readable recording medium recording a key authentication method for preventing illegal use of a service by using random numbers and a program for realizing the method.

1 is an exemplary view illustrating an authentication procedure in a wireless communication authentication system to which the present invention is applied.

2 is a flowchart of an embodiment of a key authentication method according to the present invention;

3 is a diagram illustrating an embodiment of a secret key generation process of a key authentication method according to the present invention.

4 is a detailed flowchart illustrating an embodiment of a secret key generation process of a key authentication method according to the present invention;

* Explanation of symbols for the main parts of the drawings

11 base station 12 terminal

In order to achieve the above object, the present invention provides a key authentication method in a wireless communication authentication system, comprising: a first step of a subscriber management apparatus transmitting an encrypted key generation random number and a key generation function number to a base station; A second step of decrypting, at the base station, a key generation function by decrypting a key generation random number and a key generation function number received from the subscriber management apparatus; The terminal receives a random key generation number from the base station and performs authentication with the base station using a key generation random number and a key generation function number, and determines whether to update the secret key of the terminal through the authentication result at the base station during the authentication procedure. A third step of requesting the subscriber management device to update the secret key of the terminal; And a fourth step of generating, by the subscriber management apparatus, a secret key using a random key generation key and transmitting the secret key to the terminal according to a key update request of the base station.

In addition, the present invention is characterized in that the terminal further comprises a fifth step of decrypting the received secret key and stored with the key generation function number.

The secret key generation step of the fourth step may include: an input data loading step of configuring input data using a profile of the terminal and a random number for key generation; An initialization process of setting a variable of the input data to another constant value; Performing a predetermined round of step operations and scrambling the input data; And a secret key output process of outputting a secret key.

On the other hand, the present invention provides a first function for transmitting the encrypted key generation random number and the key generation function number to the base station to the authentication system having a processor for key generation function update and secret key update; A second function of updating a key generation function by decrypting a key generation random number and a key generation function number received from the subscriber management apparatus at the base station; The terminal receives a random key generation number from the base station and performs authentication with the base station using a key generation random number and a key generation function number, and determines whether to update the secret key of the terminal through the authentication result at the base station during the authentication procedure. A third function of requesting a subscriber management device to update the secret key of the terminal; And a program for realizing a fourth function of generating a secret key by using the random number for key generation in the subscriber management apparatus and transmitting the secret key using the key generation function number to the terminal according to the key update request of the base station. Provides a record medium that can be.

The present invention also provides a computer-readable recording medium having recorded thereon a program for realizing a fifth function of decrypting the received secret key and storing the received secret key together with a key generation function number.

The secret key generation function according to the fourth function may include: an input data loading function configured to configure input data using a profile of the terminal and a random number for key generation; An initialization function for setting the variable of the input data to another constant value; A step operation function of scrambling the input data through a predetermined round of step operations; And a computer readable recording medium having recorded thereon a program for realizing a secret key output function for outputting a secret key.

The present invention is to compensate for the security problems caused by the authentication performed in the state that the base station does not have a private key of the terminal in CT-2, the process of generating a secret key using a random number and updating the key generation function The present invention relates to a processing procedure in a base station, subscriber management apparatus and terminal. Since the key generation function is updated through a random number in the present invention, it is not necessary to secure a plurality of key generation functions necessary for updating the key generation function. The key generation function is designed in the form of a hash function with a rushing effect in order to change the output value through the change of the random number used as the input value of the key generation function to bring the effect of key update.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is an exemplary view illustrating an authentication procedure in a wireless communication authentication system to which the present invention is applied.

In the present embodiment, the installation cost, usage fee, maintenance, etc. are very cheap compared to the conventional commercialized wireless network, and use the CT-2 wireless network which is almost the same level as the cost of using the subscriber line.

Now, the terminal authentication procedure in the CT-2 wireless communication authentication system will be described in detail.

First, the base station 11 generates a 32-bit random number (RAND) 101 and transmits it to the terminal 12. At this time, the terminal 12 performs an authentication function 103 that takes a received random number (RAND) 101 and a stored 64-bit secret key (KEY) 101 as an input, thereby executing a 32-bit authentication response 104. Create

Thereafter, the terminal 12 transmits an authentication response 104 to the base station 11. At this time, the terminal 12 also transmits the profile 105, which is authentication information, to the base station 11 as well. Here, the profile 105 includes "Manu key generation function acturer Identify Code", "HIC (Handset Identity Code)", "OPSIC (Operators Identification Code)", "TCOS (Terminal Class Of Service)", "ZAP" (ZAP field) "and" Terminal Registration Data ".

Next, after the base station 11 generates the secret key (KEY) 107 using the profile 105 and the key generation function 106, the generated secret key 107 is random number (RAND) 101. Together with the input of the authentication function 108 to generate an authentication response (109).

Then, the base station 11 compares the authentication response 104 received from the terminal 12 with the authentication response 108 generated by the base station 11 (110). At this time, if the comparison result value is matched, authentication is determined to be successful, and if not, it is determined to be authentication failure.

2 is a flowchart illustrating an embodiment of a key authentication method according to the present invention, which illustrates a process of updating a secret key generation function and a process of updating a secret key according to the present invention, wherein “21” is a subscriber management device and “22” is a base station. And "23" represent terminals, respectively.

As shown in FIG. 2, in the secret key generation function update process and the secret key update process according to the present invention, first, when the secret key generation function is requested to be updated, the subscriber management apparatus 21 generates a random number for key generation. (201). Here, the random number for key generation is used to update the key generation function. Since the key generation function is updated by a random number, a separate key generation function number is assigned when a random number is generated, so that the updated key generation function is used as an identifier that can be distinguished from the key generation function to be updated before or after the update.

Thereafter, after encrypting the random number for key generation for security (202), the encrypted key random number is transmitted to the base station 22 together with the key generation function number (203). Here, the encryption of the random number for key generation uses a secret key encryption method, and the secret key of the base station 22 is stored in the chip and installed in the base station 22, and each base station 22 uses a different secret key. .

Next, the base station 22 receiving the key generation random number decrypts it (204) and updates the key generation function (205).

If the terminal 23 requests network access (206), the base station 22 transmits a random number (RAND) to the terminal 23 (207). Thereafter, the terminal 23 having received the random number RAND generates an authentication response (208) and transmits it to the base station 22 together with the profile and key generation function number (209).

Subsequently, the base station 22 generates a secret key (KEY) using the profile sent from the terminal 23 (210), and generates an authentication response using the generated secret key and random number (RAND) (211). In operation 212, the authentication response generated by the user is compared with the authentication response received from the terminal 23.

As a result of the comparison, if the two values match, it is determined as authentication success (213).

As a result of the comparison, if the two values do not match, it is analyzed whether the key generation function number sent from the terminal 23 matches the key generation function number of the base station 22 (214).

As a result of the analysis, if it is determined that the authentication fails, the terminal 23 denies access to the network (215). If there is a mismatch, a secret key is generated using a random number for generating a key corresponding to the key generation function number sent from the terminal 23. After that, the authentication response is regenerated (216). Thereafter, it is checked whether the regenerated authentication response matches the authentication response of the terminal 23 again (217).

As a result of the check, if there is a mismatch, the network access of the terminal 23 is denied (218). If there is a match, it is determined that the private key of the terminal 23 is not updated, and the subscriber management apparatus 21 is requested to renew the key (219). .

Thereafter, the subscriber management apparatus 21 having received the key update request from the base station 22 generates the secret key of the terminal 23 using the profile of the corresponding terminal 23 and the current key generation function (220). Encrypted with " EPID (Encrytion Potable IDentification code) " (221) and transmitted to the terminal 23 (222). At this time, the subscriber management device 21 also transmits the key generation function number to the terminal 23 (222).

Finally, the terminal 23 receiving the secret key decrypts the secret key using its EPID (223) and stores the key generation function number together (224).

3 is a diagram illustrating an embodiment of a secret key generation process of a key authentication method according to the present invention.

Secret key generation processes 210 and 220 of the base station 22 and the subscriber management apparatus 21 of FIG. 2 according to the present invention are performed by the base station 22 or the terminal 23 during the authentication procedure as described above with reference to FIG. 2. At the time of renewal of the secret key, the subscriber management apparatus 21 is made. That is, the base station 22 generates a secret key using the profile sent by the terminal 21 and the random number for key generation stored therein, and the subscriber management apparatus 21 stores the corresponding terminal 23. Generate a secret key using your profile and a random number for key generation.

As shown in FIG. 3, the method for generating a secret key according to the present invention first performs an input data loading process for configuring input data of 192 bits using a profile and a key generation random number (301), and six 32 An initialization process of setting a bit variable to another constant value is performed (302).

Thereafter, after performing a step operation process of scrambling the input data through a step operation of two rounds (303), a process of outputting a secret key is performed (304).

As described above, the present embodiment of the wireless communication authentication system uses the method of updating the key generation function in the subscriber management apparatus, the base station, and the terminal, the secret key updating method, and the random number according to the CT-2. Input data loading process of configuring 192-bit input data using a profile of the terminal and a random number for key generation, which is a key generation method for generating a key, and an initialization process of setting six 32-bit variables to different constant values (302). ), A step operation process 303 of scrambling the input data through a step operation of two rounds, and a secret key output process 304.

4 is a detailed flowchart illustrating an embodiment of a secret key generation process among key authentication methods according to the present invention.

This embodiment is a countermeasure for preventing damage caused by security problems caused by the authentication performed when the base station does not have the private key of the terminal. Update and generate a private key. To this end, in the present embodiment, when the key generation function is updated, the result of the key generation function is changed by changing the output value of the key generation function using a random number without replacing the key generation function with another key generation function. We design a key generation function in the form of a hash function with a rush effect.

First, in order to help understanding, descriptions and conventions necessary in the present embodiment will be described.

In this embodiment, the word is a 32-bit data sequence.

, Suppose Where W_ {i, j} '' is a 32-bit word.

Word-wise modular 2 ^ 32` integer addition of S_1 and S_2` If you mark with, to be.

In this embodiment, Rotates the word X to the right of s times.

As shown in Figure 4, the secret key generation method (210, 220) in the base station 22 or subscriber management apparatus 21 according to the present invention, using the profile of the terminal and the random number for key generation (Table 1) In step 401, input data of 192 bits is configured. Here, the 192-bit input data is made up of six 32-bit words (W`` (0) W '' (1), ..., W`` (5)) and then processed in word units.

MIC (8) HIC (19) ZAP (4) TRD (80) OPSIC (9) TCOS (3) 0x15 (5) Key Generation Random Number (64)

Thereafter, six 32-bit variables (in this embodiment, all six variables are denoted by E_j` and each variable is denoted by E_j, n`) are initialized with different 32-bit constant values (402). Here, the subscript 0 of E_0` means the first round.

Next, to indicate the first round, j = 0 is set (403). Thereafter, the 6-word data stored in E_j` is stored in the temporary variable T` (404). Here, 192 bits of input data are processed in six rounds of 32 bits (one word) in each round.

Then, to represent the first step operation, i = 0 is set (405), and a Boolean function for T_i 'is calculated (406). Here, the inputs of the i-th step operation (T_i, 5`, T_i, 4`, T_i, 3`, T_i, 2`, T_i, 1) are substituted according to Table 2 below, and then the Boolean function F_j Used as an input value. This substitution is used to provide output uncorrelation between Boolean functions used in different rounds and performs coordinate transformation as shown in Table 2.

Referring to Table 2, the boolean function used in each round may be expressed as follows. That is, the Boolean function for each round is represented by F_1 (X_4, X_3, X_2, X_1, X_0) and F_2 (X_4, X_3, X_2, X_1, X_0). Where F_1 and F_2 are 5-variable Boolean functions.

Next, after the output value of the Boolean function (denoted by P in the following equation) is rotated 11 bits to the right, modular 2 ^ 32` integer addition is performed on T_i, 7 and W`` (i). The resultant value is denoted by S (407). Here, when calculating S, 32-bit random numbers K_0 and K_1 are added. When the calculation process of S is expressed by Equation (Equation 1).

Thereafter, the position of the T_i values, including S, is moved (408). That is, the position of the values of T_i & T_i + 1,5` = T_i, 4``, T_i + 1,4` = T_i, 3``, , T_i + 1,2` = T_i, 1``, T_i + 1,0` = S ''.

Then, i is compared with 5 (409), and if it is less than 5, the value of i is increased by one (410), and then the step 406 of calculating a Boolean function is obtained, and if i is not less than 5, the data of T is returned. Stored in E_j (411). That is, E_j consisting of (`` E_j, 5 `` E_j, 4 `` E_j, 3 `` E_j, 2 `` E_j, 1 `` E_j, 0 '') is (`` T_8,5 `` T_8 , 4 `` T_8,3 '' T_8,2 `` T_8,1 `` T_8,0 ''). This can be expressed as Equation (2).

E_j = (`` E_j, 5 `` E_j, 4 `` E_j, 3 '' E_j, 2 `` E_j, 1 `` E_j, 0 '')

= (`` T_8,5 '' T_8,4 '' T_8,3 '' T_8,2 `` T_8,1 '' T_8,0``)

Thereafter, j is compared with 1 (412), and if it is less than 1, the value of j is increased by one (413), and then step 404 of storing 6-word data stored in E_j` in the temporary variable T`. When the transition is made and j is not less than 1, two rounds of arithmetic operations are completed. At this time, the lowest two words (64 bits) are output as the final output value (secret key) among 196 bits of E_j, the output value of the quadratic operations. 414).

The method of the present invention as described above may be implemented as a program and stored in a computer-readable recording medium (CD-ROM, RAM, ROM, floppy disk, hard disk, magneto-optical disk, etc.).

The present invention described above is capable of various substitutions, modifications, and changes without departing from the spirit of the present invention for those skilled in the art to which the present invention pertains, and the above-described embodiments and accompanying It is not limited to the drawing.

The present invention as described above, by using a random number to securely and easily update the key generation function, to compensate for the security problems due to the authentication performed in the base station does not have a secret key of the terminal, illegal use of services There is an effect that can prevent.

Claims (9)

In the key authentication method in a wireless communication authentication system, A first step of the subscriber management apparatus transmitting the encrypted key generation random number and the key generation function number to the base station; A second step of decrypting, at the base station, a key generation function by decrypting a key generation random number and a key generation function number received from the subscriber management apparatus; The terminal receives a random key generation number from the base station and performs authentication with the base station using a key generation random number and a key generation function number, and determines whether to update the secret key of the terminal through the authentication result at the base station during the authentication procedure. A third step of requesting the subscriber management device to update the secret key of the terminal; And A fourth step of generating, by the subscriber management apparatus, a secret key using a random key generation number and transmitting the secret key to the terminal together with a key generation function number according to a key update request of the base station; Key authentication method in the authentication system comprising a. The method of claim 1, A fifth step in which the terminal decrypts the received secret key and stores it together with a key generation function number; Key authentication method in the authentication system further comprising. The method of claim 1, The random number for key generation is, It is used to update the key generation function, and since the key generation function is updated by a random number, the key generation function updated when a random number is generated is used as an identifier that can be distinguished from the key generation function to be updated before or after the update. The key authentication method in the authentication system, characterized in that a separate key generation function number is assigned. The method of claim 3, wherein The secret key generation process of the fourth step, An input data loading process of configuring input data using a profile of the terminal and a random number for key generation; An initialization process of setting a variable of the input data to another constant value; Performing a predetermined round of step operations and scrambling the input data; And Secret key output process to output secret key Key authentication method in the authentication system comprising a. The method according to any one of claims 1 to 4, The third step, Transmitting a random number (RAND) from the base station to the terminal when the terminal requests a network access; A seventh step of the terminal receiving the random number (RAND) generating an authentication response and transmitting the authentication response to the base station together with a profile and a key generation function number; The base station generates a secret key (KEY) using the profile sent by the terminal, generates an authentication response using the generated secret key and random number (RAND), and receives the authentication response generated by the terminal from the terminal. An eighth step of comparing with the authenticated response; A ninth step of determining that authentication is successful when the comparison result of the eighth step is identical to the authentication response generated by the base station and the authentication response received from the terminal; As a result of the comparison in the eighth step, when the authentication response generated by the base station and the authentication response received from the terminal do not match, a tenth step of analyzing whether the key generation function number sent by the terminal matches the key generation function number of the base station; step; As a result of the analysis of the tenth step, if the key generation function number sent by the terminal is identical with the key generation function number of the base station, it is determined that the authentication failure is denied access to the network of the terminal; An eleventh step of generating a secret key using a random number for key generation corresponding to a function number, and regenerating an authentication response; A twelfth step of checking whether the authentication response regenerated by the base station matches the authentication response of the terminal; And A thirteenth step of denying network access of the terminal if the authentication response regenerated by the base station does not match the authentication response of the terminal; Key authentication method in the authentication system comprising a. The method of claim 5, The fourth step, A fourteenth step of the base station requesting a key update to the subscriber management apparatus; And After receiving the key update request from the base station, the subscriber management apparatus generates the secret key of the terminal using the profile of the terminal and the current key generation function, and then encrypts the generated secret key with the key generation function number. 15th step of transmitting to the terminal Key authentication method in the authentication system comprising a. In the authentication system having a processor for updating the key generation function and the secret key, A first function of the subscriber management apparatus transmitting the encrypted key generation random number and the key generation function number to the base station; A second function of updating a key generation function by decrypting a key generation random number and a key generation function number received from the subscriber management apparatus at the base station; The terminal receives a random key generation number from the base station and performs authentication with the base station using a key generation random number and a key generation function number, and determines whether to update the secret key of the terminal through the authentication result at the base station during the authentication procedure. A third function of requesting a subscriber management device to update the secret key of the terminal; And A fourth function of generating a secret key by using the random number for key generation in the subscriber management apparatus according to the key update request of the base station and transmitting the secret key to the terminal together with a key generation function number; A computer-readable recording medium having recorded thereon a program for realizing this. The method of claim 7, wherein A fifth function in which the terminal decrypts the received secret key and stores it together with a key generation function number A computer-readable recording medium that records a program for further realization. The method of claim 8, Secret key generation function according to the fourth function, An input data loading function for configuring input data using a profile of the terminal and a random number for key generation; An initialization function for setting the variable of the input data to another constant value; A step operation function of scrambling the input data through a predetermined round of step operations; And Secret key output function to output secret key A computer-readable recording medium having recorded thereon a program for realizing this.