Diffie–Hellman key exchange

> Software Security > Cryptography - Key

1 - About

in 1974, the GCHQ mathematician and cryptographer, Malcolm J. Williamson developed it.

In the Diffie–Hellman key exchange scheme:

  • each party generates a keypair
  • each party distributes the public key to the party adverse
  • each party compute a shared secret (key) with the public key

The shared secret can be used, for instance, as the key for a symmetric cipher.

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3 - SSL

Secure Sockets Layer (SSL) uses:

  • Diffie–Hellman key exchange if the client does not have a public-private key pair and a published certificate in the public key infrastructure
  • Public Key Cryptography if the user does have both the keys and the credential.