Generalized privacy amplification

~ This paper provides a general treatment of privacy amplification by public discussion, a concept introduced by Bennett, Brassard and Robert [l] for a special scenario. The results have applications to unconditionally-secure secret-key agreement protocols, quantum cryptography and to a non-asymptotic and constructive treatment of the secrecy capacity of wire-tap and broadcast channels, even for a considerably strengthened definition of secrecy capacity.