Editing Brute-force attack (section)

==Unbreakable codes==
Certain types of encryption, by their mathematical properties, cannot be defeated by brute-force. An example of this is [[one-time pad]] cryptography, where every [[cleartext]] bit has a corresponding key from a truly random sequence of key bits. A 140 character one-time-pad-encoded string subjected to a brute-force attack would eventually reveal every 140 character string possible, including the correct answer – but of all the answers given, there would be no way of knowing which was the correct one. Defeating such a system, as was done by the [[Venona project]], generally relies not on pure cryptography, but upon mistakes in its implementation, such as the key pads not being truly random, intercepted keypads, or operators making mistakes.{{sfn|Reynard|1997|p=86}}