## CryptoDB

### Paper: OCB Mode

Authors: Phillip Rogaway Mihir Bellare John Black Ted Krovetz URL: http://eprint.iacr.org/2001/026 Search ePrint Search Google This paper was prepared for NIST, which is considering new block-cipher modes of operation. It describes a parallelizable mode of operation that simultaneously provides both privacy and authenticity. "OCB mode" encrypts-and-authenticates an arbitrary message $M\in\bits^*$ using only $\lceil |M|/n\rceil + 2$ block-cipher invocations, where $n$ is the block length of the underlying block cipher. Additional overhead is small. OCB refines a scheme, IAPM, suggested by Jutla [IACR-2000/39], who was the first to devise an authenticated-encryption mode with minimal overhead compared to standard modes. Desirable new properties of OCB include: very cheap offset calculations; operating on an arbitrary message $M\in\bits^*$; producing ciphertexts of minimal length; using a single underlying cryptographic key; making a nearly optimal number of block-cipher calls; avoiding the need for a random IV; and rendering it infeasible for an adversary to find "pretag collisions". The paper provides a full proof of security for OCB.
##### BibTeX
@misc{eprint-2001-11438,
title={OCB Mode},
booktitle={IACR Eprint archive},
keywords={secret-key cryptography / AES, secret-key cryptography, modes of operation},
url={http://eprint.iacr.org/2001/026},
note={unpublished NIST submission rogaway@cs.ucdavis.edu 11430 received 1 Apr 2001, last revised 18 Apr 2001},
author={Phillip Rogaway and Mihir Bellare and John Black and Ted Krovetz},
year=2001
}