KR100607463B1 - Subscriber authentication method and ciphering session key generation method for security on wireless mobile communications network - Google Patents

Abstract

The present invention relates to a method for generating a new subscriber authentication value and an initial encryption session key generation method for authentication of a mobile subscriber and encryption of transmission data and signals in consideration of security in a wireless mobile communication network.

The method for generating a subscriber authentication value in a wireless mobile communication network includes a first step of preparing a 128-bit random value and a 64-bit subscriber secret authentication key as an input of a mobile subscriber authentication algorithm, and converting the 128-bit random value into 64 bits. The second step of inputting each of the two 16 round F functions, which are components of the new mobile subscriber authentication algorithm, and the third step of generating a 64-bit output stream through the operation of the front end F function and preparing them as the rear end F function keys. The fourth stage F function receives a 64-bit random value and an output stream of the preceding F function as inputs, and generates a 64-bit output stream. The latter F function outputs a 64-bit output stream and a 64-bit random value. A fifth step of generating the final key stream 32 bits by performing an exclusive OR on a bit basis and then dividing it by 32 bits and performing an exclusive OR on a bit basis once again It includes.

Description

Subscriber authentication method and ciphering session key generation method for security on wireless mobile communications network}

1 is a block diagram of a digital mobile communication system to which the present invention is applied;

2 is a structural diagram of a subscriber authentication value generation algorithm according to an embodiment of the present invention;

3 is a structural diagram of an encryption session key generation algorithm according to an embodiment of the present invention;

4 is a flowchart illustrating a method of generating a subscriber authentication value in a wireless mobile communication network according to an embodiment of the present invention;
5 is a flowchart illustrating a method of generating an encrypted session key in a wireless mobile communication network according to an embodiment of the present invention.

※ Explanation of code about main part of drawing ※

11: wireless access network 12: infrastructure

111: mobile terminal 112: smart card

112: base station 114: mobile switching center

115: location register 116: authentication center

The present invention relates to a new subscriber authentication value generation method and an initial encryption session key generation method proposed for authentication of mobile subscribers and encryption of transmission data and signals in consideration of security in a wireless mobile communication network.

The present invention relates to matters related to subscriber authentication and data encryption for transmitting data and signal protection, which should be considered in terms of safety in a wireless mobile communication network. Conventional techniques related to this include authentication and encryption schemes in wireless mobile communication systems based on IS-41 in the United States, and authentication and protection schemes based on GSM systems in Europe.

In the United States, CAVE (Cellular Authentication and Voice Encryption Algorithm) and Shared Secret Data (SSD) algorithms are used as authentication algorithms and initial session key generation algorithms for encryption in wireless networks. In Europe, A3 (COMP128) and A8 (variant COMP128) are used respectively. These algorithms are basically based on secret-key algorithms, but since these algorithms are analyzed so much that they have many vulnerabilities, they are being suspended and improved accordingly.

The most serious threats to information in next-generation digital mobile networks are illegal tampering, eavesdropping, identity disguise, and retransmission. Against these threats, the authentication service, along with the confidentiality and integrity services, is one of the most important information protection services. In particular, authentication is an important service that can protect against identity spoofing and retransmission threats and can be used in various forms in conjunction with access control, data integrity, confidentiality, denial of containment, and audit services. In particular, digital mobile communication such as digital cellular mobile communication and personal mobile communication has the convenience of providing voice and data services regardless of time and place, while using eavesdropping as a communication medium, eavesdropping, radio recording and illegal There is a problem that the possibility of toll fraud by duplication increases. Such toll fraud is directly related to toll collection, leading to reduced profits and distrust in the provision of services.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art, and a method for generating a mobile subscriber authentication value for enabling more reliable and stable mobile subscriber authentication and transmission signal and data protection in a wireless mobile communication network environment. In addition, the present invention provides an initial encryption session key generation method for protecting transmission data.

A method for generating a mobile subscriber authentication value in a wireless mobile communication network for achieving the above object includes a first step of preparing a random value of 2n bits (n = ^2k , k is a natural number) and a subscriber secret authentication key;
Dividing the random value into two parts by n bits;
Apply a random value of the first portion divided by the second step and the subscriber secret authentication key to the first F function, and perform a bitwise exclusive OR operation on the operation result value of the first F function and the random value of the first portion A third step of obtaining a first output key stream;
Apply a random value of the second portion divided by the second step and the first output key stream to a second F function, and perform a bitwise exclusive OR on the operation result value of the second F function and the random value of the second portion. A fourth step of computing to obtain a second output key stream;
And a fifth step of dividing the second output key stream into two parts to obtain a mobile subscriber authentication value by performing an exclusive OR operation on a bit basis.
For example, a method for generating a mobile subscriber authentication value in a wireless mobile communication network includes preparing a 128-bit random value and a 64-bit subscriber secret authentication key as an input of a mobile subscriber authentication algorithm; Dividing the 128-bit random value by 64-bits into two 16-round F functions that are components of a new mobile subscriber authentication algorithm; Operation of the front end F function to generate a 64-bit output stream and prepare it as the rear end F function key; The latter F function receives a 64-bit random value and an output stream of the preceding F function as inputs, and generates a 64-bit output stream; The output stream of the 64-bit F function 64-bit is exclusively ORed in units of bits and a random value of 64 bits, and then divided by 32 bits in order to exclusively OR again in bits.

In addition, a method for generating an encrypted session key in a wireless mobile communication network according to the present invention includes a first step of preparing a random value of 2n (n = ^2k , k is a natural number) bits and a subscriber secret authentication key;
Dividing the random value into two parts by n bits;
Applying the random value of the first portion divided in the second step and the subscriber secret authentication key to the first F function, a first output key stream is obtained, and the random value of the second part and the subscriber secret authentication key are second F. Applying a function to obtain a second output key stream;
The third output key stream is obtained by applying the first output key stream and the subscriber secret authentication key to a third F function and performing a bitwise exclusive OR on the operation result value of the third F function and the first output key stream. A fourth step;
Apply the second output key stream and the third output key stream to a fourth F function, and perform an bitwise exclusive OR of the operation result of the fourth F function and the second output key stream to obtain an initial encrypted session key. And a fifth step.
For example, a method for generating an encrypted session key in a wireless mobile communication network includes preparing a 128-bit random value and a subscriber secret authentication key input to four F functions for generating an initial encrypted session key; The 128-bit random value is divided into two 64-bit random values, and the 64-bit key stream is generated by inputting the divided 64-bit random value and the subscriber secret authentication key, respectively, to two front end F functions. Then give each of the two subsequent F functions; Of the two subsequent F functions, the F function on the left generates a 64-bit output stream using the 64-bit key stream and the subscriber secret authentication key, and again performs an exclusive OR on the bit with the input key stream. Enter; The F function on the right side of the rear stage generates a 64-bit output key stream using the 64-bit key stream and the output value of the F function on the left side of the rear stage. Generate a session key value.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a configuration diagram of a general mobile communication system including an authentication center and a mobile terminal to which the present invention is applied, which is largely composed of a radio access network and a core network. The wireless access network includes a mobile terminal 111, a smart card 112, and a base station 113. The base network also includes a Mobile Switching Center 114, a Home / Visited Location Register 115, and an Authentication Center 116.

Referring to FIG. 1, when a mobile subscriber registers a service, the authentication center 116 in the base network processes a service registration and issues a smart card 112 containing an authentication and encryption algorithm to the subscriber. Through the issued smart card 112, the mobile subscriber accesses his smart card 112 to the mobile terminal 111 in the wireless access network and receives identification and authentication from the network before receiving a communication service.

In addition, since the mobile subscriber also attempts to authenticate the network based on the encryption algorithm and parameters included in the smart card 112, the mobile subscriber can protect the exposure of his / her secret information. In this case, the mobile station 111 and the base station 113 may be a wireless section, and may be transmitted by encrypting a signal or a message. After this process, the calling party subscriber may perform the secret communication between mobile subscribers by distributing session key for secret communication with the called party subscriber.

2 is a structural diagram of a mobile subscriber authentication value generation algorithm according to an embodiment of the present invention, which includes two 16-round Festel functions (hereinafter, referred to as F functions) 21 and 23 and three bit units. Exclusive OR operators 22, 24, and 27. First, the input 128-bit random value 20 is divided into 64 bits left and right and input to two F functions 21 and 23. The double function F function 21 accepts the left random value 64 bits and the subscriber secret authentication key (Ki) 64 bits to generate a 64-bit output stream, and extracts the left random value 64 bits and the bitwise exclusive unit (Exclusive). OR) to generate a 64-bit output key stream.

The rear F function 23 receives the 64-bit right random value and the 64-bit output key stream output from the exclusive-OR operator 22 to generate a 64-bit output stream, which is again converted into the right random 64-bit and the bit unit. The operation is performed with an exclusive-OR operator 24 to produce a 64-bit output stream. The 64 bits of the stream output from the exclusive OR operator 24 are divided by 32 bits (25, 26), so that the final 32 bit key stream 28 is generated through the bitwise operation of the nonlinear function exclusive OR operator 27. . This final output key stream is the mobile subscriber authentication value, and the mobile subscriber is authenticated as a valid subscriber through this authentication value.

3 is a structural diagram of an initial encryption session key generation algorithm according to an embodiment of the present invention in connection with FIGS. It is largely composed of four 16 round F functions 31, 32, 33 and 34 and two exclusive OR operators 37 and 38. First of all, the two F functions 31 and 32 receive 64 bits each of the 128 bits of the random value 35 divided by the left and the right, and the subscriber secret authentication key Ki at the same time. 36).

Prepare this again as the other two 16 round F functions (33, 34) input. The double front-end F function 33 receives the subscriber secret authentication key (Ki) value again to generate a 64-bit output stream, which is exclusive of the 64-bit output on the left side of the first two F functions (31,32) and bitwise exclusively. After calculating with the OR operation 37, the result is inputted as a key of the subsequent F function 34. The rear end F function 34 receives the 64-bit output on the right of the first two F functions 31 and 32 and the output stream of the exclusive-OR operator 37 as key values, and generates a 64-bit output stream. The input value of the F function 34 and the bitwise exclusive OR operator 38 are used to generate the final 64-bit initial encryption session key 39.

4 and 5 are flowcharts illustrating a method for generating a subscriber authentication value and a method for generating an encrypted session key in a wireless mobile communication network according to an embodiment of the present invention.

First, an operation flow of the method for generating a mobile subscriber authentication value will be described with reference to FIG. 4. 4 is a process of executing the structural diagram shown in FIG.

First, a 128-bit random value and a 64-bit subscriber secret authentication key are prepared as inputs to the mobile subscriber authentication algorithm (S41). Next, the 128-bit random value is divided into two parts by 64 bits (S42), and the random value and the subscriber secret authentication key of the first part are inputted to the 16-round F function, which is a component of the new mobile subscriber authentication algorithm, and calculated. An operation result value of the bit is obtained, and an exclusive OR operation is performed on the operation result value and the random value of the first part to obtain a first output key stream (S43).
Next, the first output key stream and the random value of the second part (64 bits) are input to the 16-round F function to operate and obtain a 64-bit operation result value, and the operation result value and the random value of the second part are exclusive. The OR operation results in a 64-bit second output key stream (S44). Then, the 64-bit second output key stream is divided into two portions of 32 bits each to perform an exclusive OR operation on a bit basis once again to obtain a final key stream of 32 bits (S45). This final key stream is set as a mobile subscriber authentication value (S46).

Next, an operation flow of the initial encryption session key generation method will be described with reference to FIG. 5. 5 is a process of executing the structural diagram shown in FIG.

First, a 128-bit random value input to four F functions and a subscriber secret authentication key are prepared for initial encryption session key generation (S51). Here, the subscriber secret authentication key uses an optional secret key of 32/64/128 bits. The 128-bit random value is divided into two parts (S52), and the 64-bit first output key stream is obtained by applying the random value of the first part and the subscriber secret authentication key to the 16 round F function, and the random value of the second part. And the subscriber secret authentication key are applied to another 16 round F function to obtain a 64 bit second output key stream (S53).

Next, the 64-bit first output key stream and the subscriber secret authentication key are applied to another 16 round F function, and the result value and the first output key stream are ORed bit-by-bit to obtain a third output key stream ( S54). Next, the second output key stream and the third output key stream are applied to the F function, and the result value and the second output key stream are ORed bit-by-bit exclusively to obtain a fourth output key stream of 64 bits (S55). This fourth output key stream is set as the initial encryption session key.
When the initial encryption session key is applied to a data encryption method in a wireless communication environment of Korean Patent Application No. 1999-28260 filed by the applicant of the present invention, an encryption key stream can be generated, and the encryption key stream and plain text information can be generated. By operating with bitwise nonlinear functions, you can generate ciphertext.

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While the invention has been described above based on the preferred embodiments thereof, these embodiments are intended to illustrate rather than limit the invention. It will be apparent to those skilled in the art that various changes, modifications, or adjustments to the above embodiments can be made without departing from the spirit of the invention. Therefore, the protection scope of the present invention will be limited only by the appended claims, and should be construed as including all such changes, modifications or adjustments.

According to the present invention as described above, the following effects can be expected.

First, because wireless mobile communication network provides more secure and reliable authentication function, it can prevent fraudulent use of mobile terminal through more reliable authentication from mobile operator's point of view, thereby reducing operator's profits and safer from subscriber's point of view. And reliable mobile communication services can be provided.

Second, the development of a new encryption initial session key generation algorithm prevents the exposure of mobile subscriber secret information in a wireless mobile communication network, thereby enabling privacy protection for mobile subscribers.

Third, since the subscriber authentication value generation algorithm that provides more secure and reliable authentication function and the initial encryption session key generation algorithm for transmission data protection are provided in wireless mobile communication network, it is possible to secure independent technology for core technology development. As a result, the technology fee for the use of foreign technology can be prevented and moreover, the technology competitiveness can be induced for the establishment of base technology development and core technology development.

Fourth, in addition to the above effects from the mobile subscriber's point of view, the necessary information and subscriber authentication algorithm is implemented in a smart card that can be mounted on the mobile terminal, so it is practically easy to implement, and this may not be limited to the mobile terminal. It is also easy to provide, economical in use, safety, reliability and utility.

Claims (2)

A first step of preparing a random value of 2n (n = 2 ^k , k is a natural number) bits and a subscriber secret authentication key; Dividing the random value into two parts by n bits; Apply a random value of the first portion divided by the second step and the subscriber secret authentication key to the first F function, and perform a bitwise exclusive OR operation on the operation result value of the first F function and the random value of the first portion A third step of obtaining a first output key stream; Apply a random value of the second portion divided by the second step and the first output key stream to a second F function, and perform a bitwise exclusive OR on the operation result value of the second F function and the random value of the second portion. A fourth step of computing to obtain a second output key stream; And a fifth step of dividing the second output key stream into two parts to obtain a mobile subscriber authentication value by performing an exclusive OR operation on a bit basis. A first step of preparing a random value of 2n (n = 2 ^k , k is a natural number) bits and a subscriber secret authentication key; Dividing the random value into two parts by n bits; Applying the random value of the first portion divided in the second step and the subscriber secret authentication key to the first F function, a first output key stream is obtained, and the random value of the second part and the subscriber secret authentication key are second F. Applying a function to obtain a second output key stream; The third output key stream is obtained by applying the first output key stream and the subscriber secret authentication key to a third F function and performing a bitwise exclusive OR on the operation result value of the third F function and the first output key stream. A fourth step; Apply the second output key stream and the third output key stream to a fourth F function, and perform an bitwise exclusive OR of the operation result of the fourth F function and the second output key stream to obtain an initial encrypted session key. A method for generating an encrypted session key in a wireless mobile communication network comprising a fifth step.

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