Anonymous Proxy Signature Scheme Research Articles

Anonymous Proxy signature scheme based on multivariate polynomials over finite field

Proxy signature schemes can be used in all the scenarios where a signer is not able to sign an important message. In some cases which involve a group of proxy signers, the anonymity of the proxy signer is required. We propose the first multivariate anonymous proxy signature scheme over finite field, and discuss all its security properties such as anonymity, unforgeability, verifiability, distinguishability, and undeniability. Additionally, we give a toy example to demonstrate the mathematical functioning of the proposed scheme. We compare our scheme with the existing post-quantum anonymous proxy signature scheme.

Secure and efficient anonymous proxy signature scheme in the random oracle model

Anonymous proxy signature scheme can provide the privacy protection for the proxy signer. Recently, Yu et al. proposed an anonymous proxy signature, which can be viewed as the organic combination of proxy signature and ring signature. However, the efficiency is low. In this paper, we propose an efficient and secure proxy signature with the properties of anonymity and traceability, and it is provably secure in the random oracle model. Compared with Yu et al.'s scheme, the scheme has higher efficiency.

On the security of an ID-based anonymous proxy signature scheme and its improved scheme

As an important delegation technique, proxy signature was introduced in 1996 by Mambo, Usuda, and Okamoto. And many variants of proxy signature schemes have been proposed. In some cases, to protect privacy of proxy signer, the identity of proxy signer is hidden. Recently, to satisfy the requirement of proxy signer’s privacy protection, Hu et al. gave an enhanced ID-based anonymous proxy signature scheme from pairings, in which it allows that proxy signature produces an anonymous signature on behalf of original signer, and the identity of proxy signer is hidden. Meanwhile, it also allows the original signer to trace the actual identity of proxy signer. Unfortunately, in this paper, by analysing the scheme, we show that the scheme is insecure. It is universally forgeable, namely, anyone can produce an anonymous proxy signature on an arbitrary message. And the original signer can not also trace the actual identity of proxy signer. Finally, we give the corresponding attacks on the scheme and the reasons to produce suck attacks. To overcome our attacks, we proposed an improved scheme based on bilinear map of composite order.

A New Anonymous but Accountable Secure Proxy Signature Scheme

Privacy has become one of the most important human rights of the modern age. In order to verify the validity of the proxy signature, the verifier need get the original signers’ public key and the proxy signer’s public key. Obviously, the verification would leak the relationship between the proxy signer and the original signer. Using the technology of pseudonym, in this paper, we propose a simple secure anonymous but accountable method for proxy signer in a proxy signature scheme. Unless the corresponding evidence has been provided by the original signer, no one can find the proxy signer’s real identity or public key. In the scheme, the can reveal the identity of the proxy signer; moreover, the original signer can also demonstrate the identity of the proxy signer. Specially, we realize the property of anonymous but accountable without complex computation and trusted third party which is different to earlier method. The method can be used in any proxy signature scheme based on warrant to reach the target of proxy signer’s anonymity and accountability.

A Novel Anonymous Proxy Signature Scheme

Recently, several studies about proxy signature schemes have been conducted. In 2009, Yu et al. proposed an anonymous proxy signature scheme attempting to protect the proxy signer's privacy from outsiders. They claimed that their scheme can make the proxy signer anonymous. However, based on our research, we determined that this was not the case and the proxy signer's privacy was not anonymous. Hence, in this paper, we propose a new anonymous proxy signature scheme that truly makes the proxy signer anonymous while making it more secure and efficient when compared with Yu et al.'s scheme. Our proxy signature scheme consists of two contributions. First, we mainly use random numbers and bilinear pairings to attain the anonymous property. Secondly, we increase the security and efficiency of our proxy in the design.

Improvement of a New Proxy Signature Scheme

In this paper, a new anonymous proxy signature scheme proposed by Gu Li-ze et al.(2005) is cryptanalyzed in detail and is proved that this scheme is not secure against the original signer’s forgery attack and then four methods to attack the new scheme are found. To avoid these attacks, the new scheme is revised and two improved schemes are given. Finally, the improved schemes are concluded that they are both secure against the original signer’s forgery attack.

An efficient anonymous proxy signature scheme with provable security

Since the concept of proxy signature was introduced in 1996, many proxy signature schemes have been proposed. Among of them, the requirement of proxy signer's privacy protection is needful in some practical applications. In this paper, a new and provably secure anonymous proxy signature scheme from bilinear pairing, which is the organic combination of proxy signature and ring signature, is proposed to provide the privacy protection for the proxy signer. As for the security analysis, we classify the adversaries into three types according to different resources they can obtain and prove in the random oracle model that, the proposed scheme is unforgeable against all kinds of adversaries. Compared with Zhang et al.'s proxy ring signature scheme proposed in 2003, our scheme is more efficient in computation.