Several new group signature schemes have been proposed in recent years. In addition, several applications for group signatures (including electronic cash) have been suggested. A new cash scheme based on a recent group signature by Ateniese, Camenisch, Joye and Tsudik is presented. Its construction uses a general framework suitable for a number of group signature schemes. We also identify the ch...

Unforgeability and blindness are two important properties of blind signature. The latter means that after interacting with various users, the signer is unable to link a valid message-signature pair. In ICCSA 2006, Zhang et al. showed that a signer in an identity-based blind signature scheme proposed by Huang et al. is able to link a valid messagesignature pair obtained by some user. They also p...

We define a new type of mix network that offers a reduced form of robustness: the mixnet can prove that every message it outputs corresponds to an input submitted by a player without revealing which input (for honest players). We call mixnets with this property reputable mixnets. Reputable mixnets are not fully robust, because they offer no guarantee that distinct outputs correspond to distinct...

We describe a credential system similar to the electronic cash system described by Chaum, Fiat and Naor. Our system uses bit commitments to create selective disclosure credentials which limit what portions of a credential the holder must reveal. We show how credentials from separate issuers can be linked to the same person in order to prevent users from pooling credentials to obtain services no...

Proxy blind Signature allows an original signer to delegate his/her signing capability to a proxy signer who performs message signing blindly on behalf of original signer but he cannot make any link between the blind signature and the identity of the message's owner. Using bilinear pairings, so many ID-based proxy blind signature (IDPBS) schemes have been proposed. But the computation cost of a...

Multiple-bank e-cash (electronic cash) model allows users and merchants to open their accounts at different banks which are monitored by the Center Bank. Some multiple-bank e-cash systems were proposed in recent years. However, prior implementations of multiple-bank e-cash all require the random oracle model idealization in their security analysis. We know some schemes are secure in the random ...

In 2004, Yang et al. proposed an efficient (t, n) threshold proxy signature scheme with known signers. However, Maimani et al. showed that a malicious original signer can forge a valid proxy signature for any message in Yang et al.’s scheme and further proposed an improvement to remedy such an attack. In this paper, we will show that in Maimani et al.s improvement, a malicious original or proxy...

Duc et al. proposed a forward-secure blind signature scheme in [1]. They claimed that the scheme is constructed from the provably secure OkamotoGuilou-Quisquater blind signature scheme. But we recently found that their scheme is insecure. In the paper, we show the scheme is universally forgeable by a simple and direct attack.

In current proxy signature schemes, an original signer delegates her signing capability to a proxy signer, and then the proxy signer can sign messages on behalf of the original signer. Although these schemes have succeeded in proxy delegations, they share a common problem. That is, a verifier cannot ascertain that a proxy signature was signed by the proxy signer during the valid delegation peri...

We build concurrently executable blind signatures schemes in the common reference string model, based on general complexity assumptions, and with optimal round complexity. Namely, each interactive signature generation requires the requesting user and the issuing bank to transmit only one message each. We also put forward the definition of universally composable blind signature schemes, and show...