Commitments are crucial to understanding and designing autonomous agents and multiagent systems. We propose a deenition of commitments that applies especially well to agents in information-rich applications, such as electronic commerce and virtual enterprises. Our approach has a number of important features, including { not gratuitously translating social concepts to psychological concepts { di...

We introduce and construct timed commitment schemes, an extension to the standard notion of commitments in which a potential forced opening phase permits the receiver to recover (with effort) the committed value without the help of the committer. An important application of our timed-commitment scheme is contract signing: two mutually suspicious parties wish to exchange signatures on a contract...

Mercurial commitments were introduced by Chase et al. [8] and form a key building block for constructing zero-knowledge sets (introduced by Micali, Rabin and Kilian [27]). Unlike regular commitments, which are strictly binding, mercurial commitments allow for certain amount of (limited) freedom. The notion of [8] also required that mercurial commitments should be equivocable given a certain tra...

Selective opening attacks against commitment schemes occur when the commitment scheme is repeated in parallel (or concurrently) and an adversary can choose depending on the commit-phase transcript to see the values and openings to some subset of the committed bits. Commitments are secure under such attacks if one can prove that the remaining, unopened commitments stay secret. We prove the follo...

For over a decade, agent research has shown that social commitments support the definition of open multiagent systems by capturing the responsibilities that agents contract toward one another through their communications. These systems, however, rely on the assumption that agents respect the social commitments they adopt. To overcome this limitation, in this paper we investigate the role of san...