The Collision Security of Tandem-DM in the Ideal Cipher Model

We prove that Tandem-DM, one of the two “classical” schemes for turning a blockcipher of 2n-bit key into a double block length hash function, has birthday-type collision resistance in the ideal cipher model. A collision resistance analysis for Tandem-DM achieving a similar birthday-type bound was already proposed by Fleischmann, Gorski and Lucks at FSE 2009 [3]. As we detail, however, the latter analysis is wrong, thus leaving the collision resistance of Tandem-DM as an open problem until now.

• Type: Journal
• Year: 2011
• Where: CRYPTO
• Authors: Jooyoung Lee, Martijn Stam, John P. Steinberger
• Keywords: CRYPTO 2011, Cryptology, Hash Function, Lucks, Resistance Analysis