Universally Composable Protocols with Relaxed Set-Up Assumptions

A desirable goal for cryptographic protocols is to guarantee security when the protocol is composed with other protocol instances. Universally Composable (UC) protocols provide this guarantee in a strong sense: A protocol remains secure even when composed concurrently with an unbounded number of instances of arbitrary protocols. However, UC protocols for carrying out general tasks are known to exist only if a majority of the participants are honest, or in the common reference string (CRS) model where all parties are assumed to have access to a common string that is drawn from some pre-defined distribution. Furthermore, carrying out many interesting tasks in a UC manner and without honest majority or set-up assumptions is impossible, even if ideally authenticated communication is provided. A natural question is thus whether there exist more relaxed set-up assumptions than the CRS model that still allow for UC protocols. We answer this question in the affirmative: we propose alternative...

• Type: Conference
• Year: 2004
• Where: FOCS
• Authors: Boaz Barak, Ran Canetti, Jesper Buus Nielsen, Rafael Pass
• Keywords: FOCS 2004, Relaxed Set-up Assumptions, Set-up Assumption, Theoretical Computer Science, UC Protocols