The only cryptographic system that is perfectly secure is the one-time pad (OTP): in essence, a system in which every plaintext message is encrypted in a different, truly random key whose length is equal to the length of the message, and which is never reused. In practice, a OTP may be implemented in a way that is not secure, i.e., because of departures from randomness or reuse of key sequences.

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- The Grantville Gazette Staff