12:00 -- 13:00
Mixing blind signatures freely with encryption
Chennai Mathematical Institute.
In formal models of security protocols, a crucial element is the abstraction of cryptographic primitives as operations in a term algebra. The basic model has a subterm property leading to PTIME procedures for the term derivability problem. We consider an extension of the basic model to include a new cryptographic primitive, namely blind signatures. The operation of blind pairing is distributive over encryption, which destroys the simple subterm property, and hence known techniques for the term derivability problem do not work. We present an automaton saturation algorithm and show that the problem is DEXPTIME-complete.
The work is joint with R. Ramanujam (IMSc) and S. P. Suresh (CMI).