Learn More
Several credential systems have been proposed in which users can authenticate to services anonymously. Since anonymity can give users the license to misbehave, some variants allow the selective deanonymization (or linking) of misbehaving users upon a complaint to a trusted third party (TTP). The ability of the TTP to revoke a user's privacy at any time,(More)
Identity-based cryptosystems have an inherent key escrow issue, that is, the Key Generation Center (KGC) always knows user secret key. If the KGC is malicious, it can always impersonate the user. Certificateless cryptography, introduced by Al-Riyami and Paterson in 2003, is intended to solve this problem. However, in all the previously proposed(More)
k-times anonymous authentication (k-TAA) schemes allow members of a group to be authenticated anonymously by application providers for a bounded number of times. Dynamic k-TAA allows application providers to independently grant or revoke users from their own access group so as to provide better control over their clients. In terms of time and space(More)
In an attribute-based signature (ABS), users sign messages with any predicate of their attributes issued from an attribute authority. Under this notion, a signature attests not to the identity of the individual who signed a message, but a claim regarding the attributes the underlying signer possesses. In ABS, users cannot forge signatures with attributes(More)
Several anonymous authentication schemes allow servers to revoke a misbehaving user's ability to make future accesses. Traditionally, these schemes have relied on powerful TTPs capable of deanonymizing (or linking) users' connections. Recent schemes such as <i>Blacklistable Anonymous Credentials (BLAC)</i> and <i>Enhanced Privacy ID (EPID)</i> support(More)
Several credential systems have been proposed in which users can authenticate to service providers anonymously. Since anonymity can give users the license to misbehave, some variants allow the selective deanonymization (or linking) of misbehaving users upon a complaint to a Trusted Third Party (TTP). The ability of the TTP to revoke a user&#8217;s privacy(More)
Very recently, the concept of Traceable Identity-based En-cryption (IBE) scheme (or Accountable Authority Identity based En-cryption scheme) was introduced in Crypto 2007. This concept enables some mechanisms to reduce the trust of a private key generator (PKG) in an IBE system. The aim of this paper is threefold. First, we discuss some subtleties in the(More)
Certificateless Public Key Cryptography (CL-PKC) enjoys a number of features of Identity-Based Cryptography (IBC) while without having the problem of key escrow. However, it does suffer to an attack where the adversary, Carol, replaces Alice's public key by someone's public key so that Bob, who wants to send an encrypted message to Alice, uses Alice's(More)
A ring signature scheme is a group signature scheme with no group manager to setup a group or revoke a signer. A linkable ring signature, introduced by Liu, et al. [20], additionally allows anyone to determine if two ring signatures are signed by the same group member (a.k.a. they are linked). In this paper, we present the first separable link-able ring(More)