New answers tagged crc
Well, 32 bits is somewhat short, so one could just try ciphertexts. However, there is a much better attack. Choose M0 arbitrarily, let P be the CBC padding for Headers || CRC || M0, and choose M1 so that CRC( M0 || P || M1 ) = CRC(M0). Submit M0 || P || M1 to be encrypted, truncate the ciphertext to the length of encryptions of M0, and then output the ...
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