Cryptography

Cryptography is the discipline of constructing and analyzing methods for secure communication in the presence of adversaries, covering the encryption of messages so that only an intended recipient can read them as well as the broader problems of authentication and data integrity. Its history stretches from simple substitution ciphers used in antiquity through mechanical cipher devices such as the Enigma machine of the Second World War, to the modern mathematical field built on computational hardness assumptions that emerged after Claude Shannon's 1949 paper establishing the theoretical foundations of secure communication. Public-key cryptography, introduced by Whitfield Diffie and Martin Hellman in 1976, made secure communication between parties who share no prior secret practical and underlies most cryptography in use today.