A Symbolic Intruder Model for Hash-Collision Attacks
  In the recent years, several practical methods have been published to compute collisions on some commonly used hash functions. In this paper we present a method to take into account, at the symbolic level, that an intruder actively attacking a protocol execution may use these collision algorithms in reasonable time during the attack. Our decision procedure relies on the reduction of constraint solving for an intruder exploiting the collision properties of hush functions to constraint solving for an intruder operating on words. 
Yannick Chevalier (IRIT), Mounira Kourjieh (IRIT)