Most discussions of Internet privacy, both policy and technology, tend to assume Alan Westin’s perspective [20], which defines privacy as the ability for people to determine for themselves “when, how, and to what extent, information about them is communicated to others”. However, this focus on controlling information access has been found to be flawed [7]. This year’s technology press is filled...

Accountability of distributed systems aims to ensure that whenever a malicious behavior is observed, it can be irrefutably linked to a malicious node and that every honest node can disprove false accusations. Recent work, such as PeerReview and its extensions, shows how to achieve accountability in both deterministic and randomized systems. The basic idea is to generate tamper-evident logs of t...

Sanitizable signature (SS) allows a signer to partly delegate signing rights to a predetermined party, called sanitizer, who can later modify certain designated parts of a message originally signed by the signer and generate a new signature on the sanitized message without interacting with the signer. One of the important security requirements of sanitizable signatures is accountability, which ...

Formal models and security proofs are especially important for multisignatures: in contrast to threshold signatures, no precise definitions were ever provided for such schemes, and some proposals were subsequently broken. In this paper, we formalize and implement a variant of multi-signature schemes, Accountable-Subgroup Multisignatures (ASM). In essence, ASM schemes enable any subgroup, S, of ...

In this paper, we introduce accountable virtual machines (AVMs). Like ordinary virtual machines, AVMs can execute binary software images in a virtualized copy of a computer system; in addition, they can record non-repudiable information that allows auditors to subsequently check whether the software behaved as intended. AVMs provide strong accountability, which is important, for instance, in di...