Video Over IP, 2nd Edition

Appendix A

 

 

DIFFIE-HELLMAN KEY EXCHANGE

In 1976, Whitfield Diffie and Martin Hellman published a paper¹ that first described one of the key underlying technologies for exchanging cryptographic keys between two parties that wish to communicate. This process, which has come to be known as the Diffie-Hellman key exchange, is now in common use throughout the Internet, particularly since the key U.S. patents covering this technology expired in 1997. Since this is such an important technology, let's look at how it works.

Let's say two users, whom we'll call Bonnie and Clyde, are trying to exchange a secret message. In order to do this, they need to agree on a common key that will be used to encrypt messages by the sender and decrypt messages for ...