KR20030008453A - Method of inter-authentication and security service using user-password in SMS for CDMA network - Google Patents

Abstract

PURPOSE: A mutual authentication and security service method using user's password at bidirectional short message service on cdma network is provided to be capable of realizing a security-needed service on a wireless communication by providing a mutual authentication and security service at a bidirectional short message service. CONSTITUTION: A security short message service(SSMS) server(300) generates a temporary key using an identification number and a password of a user. The SSMS server(300) generates random numbers to be used when generating a section key, and encodes the temporary key to be transferred to a mobile terminal(360). A user of the mobile terminal(360) inputs own password to generate a temporary key. The user of the mobile terminal(360) decodes the temporary key to regenerate random numbers. The server(300) and the mobile terminal(360) generate secondary temporary keys using the regenerated random numbers respectively, and the secondary temporary keys are used for parameter encoding and decoding of a challenge-response protocol. A final section key is generated using two temporary keys and the second random numbers generated in the server(300). User data is encoded and decoded with the section key.

Description

Method of inter-authentication and security service using user-password in SMS for CDMA network}

The present invention relates to a short message service among application services on CDMA, and more particularly, to a communication protocol and an implementation algorithm for providing a mutual authentication and security service in a bidirectional short message service to implement a service requiring security on a wireless network.

The conventional short message service is largely divided into one-way and two-way. This short message service is part of the CDMA standard, and all mobile phones in Korea currently provide short message service.

1 illustrates a conventional short message service configuration, wherein the message transmitter 100, the message center 110, the data network 120, the cellular switch 130, the base station 140, and the mobile communication terminal 150 are illustrated in FIG. Is done.

2 shows a protocol hierarchy diagram for a conventional short message service.

The short message service protocol is composed of three layers: a short message service teleservice layer, a short message service transport layer, and a short message service relay layer.

The link layer connects to a base station (140) using EIA / TIA / IS-95A. The short message service transmission layer and the relay layer need not be connected to the actual message center 110 end-to-end, but the teleservice layer of the short message service should be connected end-to-end with the message center 110. Therefore, the base station 140 and the message center 110 are connected by a wired network to the transport layer through the EIA / TIA / IS-95A and its upper short message service transport layer and the relay layer.

Currently, short message service is not secured. This is because of the size of the short message, it is not possible to put enough information in the short message when using the public key for mutual authentication. The short message service currently used in Korea supports up to 80 bytes of data. However, public key algorithms require much larger data.

For example, Diffelmann's public key algorithms or RSA public key algorithms typically have a minimum public key size of 512 bits, usually 1024 bits. That is, the size of the public key is at least 64 bytes, usually 128 bytes. Therefore, the CA's public key included in the certificate necessary for the use of the public key is combined and the public key cannot be included within 80 bytes.

The elliptic curve public key encryption algorithm is known to provide about 1024 bits of security of RSA with only 128 bits. However, only two public keys occupy 32 bytes, and other parameters are more than 32 bytes, so only 16 bytes of data can actually be sent. Also, in order to establish a session, the payload is generated by the protocol itself, which is not practical.

The technical problem to be achieved by the present invention is to provide a communication protocol that can implement a service that requires security in wireless communication by providing mutual authentication and security services in a two-way short message service.

In addition, the present invention provides a wireless banking service method using a two-way short message service.

1 is a block diagram of a conventional short message service.

2 shows a protocol hierarchy diagram for a conventional short message service.

3 is a block diagram of a mutual authentication and security service using a user password in a bidirectional short message service on a CDMA network according to the present invention.

4 illustrates a protocol hierarchy diagram for mutual authentication and security services using a user password in a bidirectional short message service on a CDMA network according to the present invention.

In the bidirectional short message service according to the present invention for solving the technical problem, the mutual authentication and security service method using a user password (a) creates a temporary key with a user identification number and a password, and generates a random number to be used for generating a session key. And encrypting the random number with a temporary key and transmitting the random number to a wireless terminal: (b) generating a temporary key by inputting a user's password into the wireless terminal, and then decrypting and playing the random number; (c) generating a second temporary key for each of the server and the wireless terminal with the reproduced random number; (d) generating a session key including the two temporary keys and a second random number generated by the server; And (e) encrypting and decrypting using the session key.

In addition, the session key is limited to one session or transaction, and the session is terminated or disconnected, and another session key is generated.

In addition, the session key ensures the randomness of the session key by using two random numbers in the generation process, and is characterized by preventing brute-force attacks and offline dictionary attacks.

According to another aspect of the present invention, there is provided a wireless banking service method using a bidirectional short message service, comprising: (a) connecting a short message center of a mobile communication service provider to a secure short message server of a bank; (b) transmitting contents provided by the bank to a wireless terminal through a short message center of a mobile communication provider in an encrypted state through the secure short message server; And (c) decrypting the data transmitted from the secure short message server to the wireless terminal.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

3 is a diagram illustrating a mutual authentication and security service configuration using a user password in a bidirectional short message service on a CDMA network according to the present invention, and includes a secure message (SSMS) server 300, a message transmitter 310, and a data network 320. ), A message center 330, a cellular switch 340, a base station 350, and a mobile communication terminal 360.

4 illustrates a protocol hierarchy diagram for mutual authentication and security services using a user password in a bidirectional short message service on a CDMA network according to the present invention.

The short message service protocol according to the present invention is composed of four layers of a secure short message service (SSMS) layer, a short message service teleservice layer, a short message service transport layer, and a short message service relay layer.

The link layer uses EIA / TIA / IS-95A, and the base station 350 is connected to the mobile communication terminal 360 and the message center 330. The message center 330 is also a secure short message service server 300. Is connecting with. The short message service transmission layer and the relay layer need not be connected to the actual message center 330 end-to-end, but the teleservice layer of the short message service should be connected to the message center 330 end-to-end. Accordingly, the base station 350 and the message center 330 are connected by a wired network to the transport layer through the EIA / TIA / IS-95A and the upper short message service transport layer and the relay layer.

In the present invention, mutual authentication and security are provided using only the user's password, and the user's password is managed differently for each content provider.

Therefore, the SSMS server 300 first generates a temporary key with the user identification number and password, generates a random number to be used for generating the session key, and then encrypts it with the temporary key and transmits it to the mobile communication terminal 360.

The user of the mobile communication terminal 360 generates a temporary key by inputting his / her password and decrypts and reproduces the random number.

With this reproduced random number, the server 300 and the mobile communication terminal 360 each create a second temporary key and use it for parameter encryption and decryption of the challenge-response protocol.

The finally generated session key is generated including the first two keys and the second random number generated with the SSMS server 300. After that, all user data is encrypted and decrypted with this session key.

The life of this session key is limited to one session or transaction so that the session ends or is disconnected and another session key must be generated.

Two random numbers are used in the session key generation process to ensure the randomness of the session key and to prevent brute-force attacks and offline dictionary attacks.

1. Message header composition of two-way security short message is as follows.

Message: = {

UCHAR8 MSG_HDR;

UCHAR8 SSN_HDR (3);

UCHAR8 DATA_LEN (2);

UCHAR8 DATA (32..60);

UCHAR8 MAC 8;

}

MSG_HDR: = MSG_TYPE | VERSION;

MSG_TYPE

Definition: Message format

Length: 4bits

Encoding: 1000-encrypted one-way short message

1001-encrypted bidirectional short message

0000-plain one-way short message

0001-Plain Text Bidirectional Short Message

VERSION

Definition: Current version of the protocol

Length: 4bits

Encoding: The first two digits are MAIN VERSION and the next two digits are SUB VERSION. In other words, 1.1 means 0101.

SSN-HDR: = {

UCHAR8 SSN_INFO (2);

UCHAR8 MSG_FRAG;

}

SSN_INFO: = SSN_ID | SEQ_NO

SSN_ID

Definition: Each session identification number

Length: 8bit

SEQ_NO

Definition: The message sequence number in each session

Length: 8bit

MSG_FRAG: = FLAG | FSEQ_NO

FLAG

Definition: Packet Fragmentation Flag

Length: 1bit

Encoding: 0- not fragmented

One

MSG_LEN

Definition: Length of each short message

Length: 16bit

Encoding: little-endian

DATA

Definition: Encrypted message

Length: variable (maximum length is about 480 bits)

MAC

Definition: Message authentication code. This message authentication code uses the value obtained by XORing the left 64 bits and the right 64 bits of the original text by applying the one-way hash function.

Length: 64bit

2. Two-way authentication and key exchange protocol through user password of two-way security short message are as follows.

2.1 Restrictions

Maximum message length: 40 bytes (Plaintext message with 7bit encoding)

Other limitations are the same as for unidirectional cases.

2.2 Definition of Terms

ID _user : User identification number for each content provider, 8byte

PW _user : User password for each content provider, 8byte

r ₁ : Random number used to generate shared secret key, 8byte

r ₂ : Random number used to generate shared secret key, 8byte

C ₁ : random challenge sent from SSMS to MS, 16byte

C ₂ : random challenge sent from MS to SSMS, 16byte

K ₁ : first inferred shared secret key, 16byte

K ₂ : Second inferred shared secret key, 16byte

K _s : shared secret key, 16byte

IV: initial vector, 16 bytes

2.3 Shared Secret Key Generation Process

K ₁ : f ₁ (h (ID _user ), h (PW _user ), h (ID _CP ), PRNG (h (r ₁ ), h (PW _user )))

K ₂ : f ₂ (PRNG (h (r ₂ ), h (PW _user )), K ₁ , h (ID _user ), h (PW _user ))

K _s : f ₃ (K ₁ , K ₂ , h (PW _user ))

2.3.1 Key Generation Process

Both one-way and two-way services use the same key inference function, but in the one-way use only f ₃ and in both directions.

Key inference functions are basically defined based on the multi-level encryption technique, and the result values of each function do not have a specific sequence.

First, the definition of each function is as follows.

K ₁ : f ₁ (X ₁ , X ₂ , X ₃ , X ₄ )

K ₂ : f ₂ (X ₁ , X ₂ , X ₃ , X ₄ )

K _s : f ₃ (X ₁ , X ₂ , X ₃ )

Definition: f ₁ (X ₁ , X ₂ , X ₃ , X ₄ )

y = f ₁ (X ₁ , X ₂ , X ₃ , X ₄ ) = PRNG (h (PRNG (h (PRNG (X ₁ , X ₄ )), X ₃ )), X ₂ )

Definition: f ₂ (X ₁ , X ₂ , X ₃ , X ₄ )

y = f ₂ (X ₁ , X ₂ , X ₃ , X ₄ ) = PRNG (h (PRNG (h (PRNG (X ₁ , X ₂ ), X ₃ )), X ₄ )

Definition: f ₃ (X ₁ , X ₂ , X ₃ )

y = f ₃ (X ₁ , X ₂ , X ₃ ) = PRNG (h (PRNG (X ₃ , X ₂ ), X ₁ )

Each of these functions is based on a random number generator, but the random number generator is based on a stepwise encryption scheme, and the order of the parameters of each function is divided into three groups: public information, private information, and inferred information. Was decided. These functions can be arbitrarily defined if only the sequence of result values is impossible to predict and only the number of each parameter matches.

In addition, a description will be given of a wireless banking system that can be said to be a specific embodiment according to the present invention.

In order to establish a wireless banking system, first of all, a mobile operator, a bank, and a wireless terminal operator must participate.

A mobile operator provides a connection between its short message center and the bank's secure short message server via a bank and leased line.

The bank, as a content provider, transmits its content to the wireless terminal through the mobile provider's short message center in an encrypted state through a secure short message server. The wireless terminal operator upgrades the software of his wireless terminal to enable the secure short message service.

The upgraded wireless terminal can decrypt the data received from the secure short message server.

The drawings and specification are merely exemplary of the invention, which are used for the purpose of illustrating the invention only and are not intended to limit the scope of the invention as defined in the appended claims or claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

According to the present invention, it is possible to provide a variety of services that were not possible with the existing short message service without security.

This enables services that were available only in existing wireless Internet phones to existing older terminals. For example, existing older terminals that do not have a wireless Internet phone donation can be provided with services such as wireless financial transactions or securities transactions through simple software upgrades.

Claims (5)

(a) creating a temporary key with a user identification number and a password, generating a random number to be used for generating a session key, and encrypting the random number with a temporary key and transmitting it to the wireless terminal: (b) generating a temporary key by inputting a password of a user to the wireless terminal, and then decrypting and playing a random number; (c) generating a second temporary key for each of the server and the wireless terminal with the reproduced random number; (d) generating a session key including the two temporary keys and a second random number generated by the server; And (e) mutual authentication and security method using a user password in a two-way short message service, characterized in that it comprises the step of encrypting and decrypting using the session key. The method of claim 1, wherein the session key Mutual authentication and security method using a user password in a two-way short message service characterized in that the session is terminated or disconnected and generates another session key limited to one session or transaction. The method of claim 1, wherein the session key Mutual authentication and security method using user password in two-way short message service, which guarantees randomness of session key by using two random numbers in generation process and prevents brute-force attack and offline dictionary attack. In the wireless banking service method using a short message service, (a) connecting the short message center of the mobile communication provider with the secure short message server of the bank; (b) transmitting contents provided by the bank to a wireless terminal through a short message center of a mobile communication provider in an encrypted state through the secure short message server; And and (c) decrypting data transmitted from the secure short message server to the wireless terminal. The method of claim 4, wherein step (c) And upgrading the software of the wireless terminal provided by the wireless terminal operator to enable a secure short message service.