On the Security of Tandem-DM

Ewan Fleischmann; Michael Gorski; Stefan Lucks

Paper 2009/054

On the Security of Tandem-DM

Ewan Fleischmann, Michael Gorski, and Stefan Lucks

Abstract

We provide the first proof of security for Tandem-DM one of the oldest and most well-known constructions for turning a blockcipher with n-bit blocklength and 2n-bit keylength into a 2n-bit cryptographic hash function. We prove, that when Tandem-DM is instantiated with AES-256, i.e. blocklength 128 bits and keylength 256 bits, any adversary that asks less than 2^{120.4} queries cannot find a collision with success probability greater than 1/2. We also prove a bound for preimage resistance of Tandem-DM. Interestingly, as there is only one practical construction known (FSE'06, Hirose) turning such an (n,2n)-bit blockcipher into a 2n-bit compression function that has provably birthday-type collision resistance, Tandem-DM is one out of two structures that possess this desirable feature.

Metadata

Available format(s): PDF
Category: Secret-key cryptography
Publication info: Published elsewhere. an extended abstract of this paper will appear at FSE 2009 proceedings, this is the full version
Keywords: hash function blockcipher based proof of security double block length ideal cipher
Contact author(s): ewan fleischmann @ uni-weimar de
History: 2009-02-04: revised; 2009-02-04: received; See all versions
Short URL: https://ia.cr/2009/054
License: CC BY

BibTeX

@misc{cryptoeprint:2009/054,
      author = {Ewan Fleischmann and Michael Gorski and Stefan Lucks},
      title = {On the Security of Tandem-{DM}},
      howpublished = {Cryptology {ePrint} Archive, Paper 2009/054},
      year = {2009},
      url = {https://eprint.iacr.org/2009/054}
}