Paper 2012/380

Several Weak Bit-Commitments Using Seal-Once Tamper-Evident Devices

Ioana Boureanu and Serge Vaudenay

Abstract

Following both theoretical and practical arguments, we construct UC-secure bit-commitment protocols that place their strength on the sender’s side and are built using tamper-evident devices, e.g., a type of distinguishable, sealed envelopes. We show that by using a second formalisation of tamper-evident distinguishable envelopes we can attain better security guarantees, i.e., EUC-security. We show the relations between several flavours of weak bit-commitments, bit-commitments and distinguishable tamper-evident envelopes. We focus, at all points, on the lightweight nature of the underlying mechanisms and on the end-to-end human verifiability.