Oblivious Transfer is Incomplete for Deniable Protocols

Oblivious Transfer is Incomplete for Deniable Protocols (Workshop on The Past, Present and Future of Oblivious Transfer, 2005)
Jörn Müller-Quade, Stefan Röhrich, Dominique Unruh
[ eprint ]

We prove that for deniable protocol tasks oblivious transfer is not complete. We introduce the protocol task of bit commitments which can be undone, and prove that this task cannot be realised with OT whereas there exists a secure realisation using string-OT.