5117 shaares
An example of using OpenSSL operations to perform a Diffie-Hellmen secret key exchange (DHKE). The goal in DHKE is for two users to obtain a shared secret key, without any other users knowing that key. The exchange is performed over a public network, i.e. all messages sent between the two users can be intercepted and read by any other user. The protocol makes use of modular arithmetic and especially exponentials. The security of the protocol relies on the fact that solving a discrete logarithm (the inverse of an exponential) is practically impossible when large enough values are used.