A Multi-Use Unidirectional Proxy Re-Signature Scheme
Jonas Özgan (cosec - b-it)
Thursday 10 December l 2009, 15.00, b-it 1.25 (cosec meeting room)
In 1998, Blaze, Bleumer, and Strauß introduced "proxy re-signatures", in which a semi-trusted proxy converts signatures of Alice into signatures of Bob on the same message. This proposal was widely ignored until 2005 when Ateniese and Hohenberger revised and formalized it by bringing new security definitions and applications for proxy re-signatures. In their proposal they also introduced two new signature schemes which are (1) Single-Use Uni-directional and (2) Multi-use Uni-directional. The left open challenge to find a "Multi-Use Unidirectional" scheme was later picked up in 2008 by Libert and Vergnaud. My talk will focus on this quite interesting signature scheme, analysing its construction and properties. We also take a look at the different challenges which seem to occur naturally due the construction of the signature scheme.
Slides (PDF).