One-time pad cryptography

In cryptography, the one-time pad (OTP) is a type of encryption, which has been proven to be impossible to crack if used correctly. The plaintext is encrypted with a substitution cipher using a secret random key (or pad) as long as the plaintext, resulting in a ciphertext. If the key is truly random, as large as the plaintext, never reused in whole or part, and kept secret, the ciphertext will be impossible to decrypt or break without knowing the key. It has also been proven that any cipher with the perfect secrecy property must use keys with effectively the same requirements as OTP keys. However, practical problems have prevented one-time pads from being widely used.

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