[Cryptography] FW: RFC 7253 on The OCB Authenticated-Encryption Algorithm

Dave Horsfall dave at horsfall.org
Sun Jun 1 19:25:14 EDT 2014


On Sun, 1 Jun 2014, Jerry Leichter wrote:

> Text from the Draft RFC:  "It is crucial that, as one encrypts, one does 
> not repeat a nonce.  The inadvertent reuse of the same nonce by two 
> invocations of the OCB encryption operation, with the same key, but with 
> distinct plaintext values, undermines the confidentiality of the 
> plaintexts protected in those two invocations and undermines all of the 
> authenticity and integrity protection provided by that key."

Which is pretty much how Enigma was broken.  Of course, to be fair, the 
operator in question probably had bombs dropping around his ears, and 
forgot to change the rotor settings.  Understandable, I guess...

-- Dave


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