Impossible plaintext cryptanalysis and probable-plaintext collision attacks of 64-bit block cipher modes

David McGrew

Paper 2012/623

Impossible plaintext cryptanalysis and probable-plaintext collision attacks of 64-bit block cipher modes

David McGrew

Abstract

The block cipher modes of operation that are widely used (CBC, CTR, CFB) are secure up to the birthday bound; that is, if or fewer bits of data are encrypted with a -bit block cipher. However, the detailed security properties close to this bound are not widely appreciated, despite the fact that -bit block ciphers are sometimes used in that domain. This work addresses the issue by analyzing plaintext-recovery attacks that are effective close to that bound. We describe possible-plaintext attacks, which can learn unknown plaintext values that are encrypted with CBC, CFB, or OFB. We also introduce \textit{impossible plaintext} cryptanalysis, which can recover information encrypted with CTR, and can improve attacks against the aforementioned modes as well. These attacks work at the birthday bound, or even slightly below that bound, when the target plaintext values are encrypted under a succession of keys.

Metadata

Available format(s): PDF
Category: Secret-key cryptography
Publication info: Published elsewhere. Unknown where it was published
Keywords: block ciphers cryptanalysis
Contact author(s): mcgrew @ cisco com
History: 2012-11-20: revised; 2012-11-05: received; See all versions
Short URL: https://ia.cr/2012/623
License: CC BY

BibTeX

@misc{cryptoeprint:2012/623,
      author = {David McGrew},
      title = {Impossible plaintext cryptanalysis and probable-plaintext collision attacks of 64-bit block cipher modes},
      howpublished = {Cryptology {ePrint} Archive, Paper 2012/623},
      year = {2012},
      url = {https://eprint.iacr.org/2012/623}
}