The Security of the Extended Codebook (XCB) Mode of Operation

  title={The Security of the Extended Codebook (XCB) Mode of Operation},
  author={David A. McGrew and Scott R. Fluhrer},
  booktitle={IACR Cryptology ePrint Archive},
The XCB mode of operation was outlined in 2004 as a contribution to the IEEE Security in Storage effort, but no security analysis was provided. In this paper, we provide a proof of security for XCB, and show that it is a secure tweakable (super) pseudorandom permutation. Our analysis makes several new contributions: it uses an algebraic property of XCB’s internal universal hash function to simplify the proof, and it defines a nonce mode in which XCB can be securely used even when the plaintext… CONTINUE READING