Original: Diffie-Hellman key exchange In 1976, Whitfield Diffie and Martin Hellman published a cryptographic protocol, (Diffie-Hellman key exchange), which allows users to establish 'secure channels' on which to exchange keys, even if an Opponent is monitoring that communication channel.
Simplified: In 1976, Whitfield Diffie and Martin Hellman published a cryptographic protocol, (Diffie-Hellman key exchange), which allows users to establish secure channels in order to exchange keys, even if an attacker is monitoring that communication channel.