impractical for many applications.

First described by Frank Miller in 1882, the one-time pad was re-invented in 1917. On July 22, 1919, U.S. Patent 1,310,719 was issued to Gilbert Vernam for the XOR operation used for the encryption of a one-time pad. One-time use came later, when Joseph Mauborgne recognized that if the key tape were totally random, then cryptanalysis