Gilbert Vernam

Who was Gilbert Vernam?

Gilbert Sandford Vernam was an AT&T Bell Labs engineer who, in 1917, invented an additive polyalphabetic stream cipher and later co-invented an automated one-time pad cipher. Vernam proposed a teleprinter cipher in which a previously prepared key, kept on paper tape, is combined character by character with the plaintext message to produce the ciphertext. To decipher the ciphertext, the same key would be again combined character by character, producing the plaintext. Vernam later worked for Postal Telegraph Co., and became an employee of Western Union when W.U. acquired Postal in 1943. His later work was largely with automatic switching systems for telegraph networks.