Secure data transmission links

Abstract

A method of establishing a secure communications link between a mobile terminal and a server, the method comprising retrieving from storage, in the mobile terminal a prime number, p, and generator, g, for a Diffie-Hellman key exchange protocol, generating a positive integer b at the terminal, sending a message including the value of (g<=[b] mod p) from the terminal to the server, determining a shared secret number for the terminal and the server by calculating the value of g<=[ab] mod p, where a is a positive integer, using b and a public value for the server y=g<=[a] mod p at the terminal, and using a, b, g and p at the server, and using the shared secret number to establish the secure communications between the terminal and the server. The method facilitates download of software to a mobile communications system terminal.

Description

technical field [0001] The present invention relates generally to secure communication links for data transmission and, more particularly, to data communication links using asymmetric cryptography to establish a secure link using symmetric cryptography. Background technique [0002] In mobile telephony networks, data transmission is becoming more and more important, especially with regard to standards and technical specifications as devised by the Third Generation Partnership Project (3GPP, 3GPP2) (available at www. This becomes especially important for the so-called 2.5G and 3G (third generation) networks described in .3gpp.org and incorporated herein by reference). [0003] Secure data transmission is important for m-commerce, but in addition, for multimedia entertainment, telemedicine (telle-medicine), upgrade of programmable mobile terminals, upgrade of different wireless standards, etc. It is also important to download and install on the mobile terminal. Reconfigurabl...

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