Section: New Results

Composition Results

Participants : Céline Chevalier, Stéphanie Delaune, Steve Kremer.

Céline Chevalier, Stéphanie Delaune, and Steve Kremer investigate the composition of protocols that share a common weak secret [32] . This situation arises when users employ the same password on different services. More precisely they study whether resistance against guessing attacks composes when a same password is used. More precisely, they present a transformation which maps a password protocol that is secure for a single protocol session (a decidable problem) to a protocol that is secure for an unbounded number of sessions. Their result provides an effective strategy to design secure password protocols: (i) design a protocol intended to be secure for one protocol session; (ii) apply the transformation and obtain a protocol which is secure for an unbounded number of sessions. This technique also applies to compose different password protocols allowing one to obtain both inter-protocol and inter-session composition.