Three attacks on Yu Gang et al’s scheme to show that their forward secure proxy-signcryption scheme based on identity is insecure.Their scheme cannot resist revising proxy warrant attack,revising proxy signer attack and proxy relationship inversion attack.Then,an improved scheme is proposed.
A quantum proxy signature scheme makes the proxy signer can generate a quantum signature on behalf of the original signer. Although many quantum proxy signature schemes have been proposed, none of them can be formally proved to be secure. There is not even security model for the quantum proxy signatures. Some quantum proxy signature schemes have been proved to be insecure against forgery attacks. In this paper, first, the formal definition and the corresponding security model for the quantum proxy signatures are proposed. Second, based on the Hadamard operator and the controlled NOT operation, a new quantum proxy signature scheme is proposed. The security of our quantum proxy signature scheme can be formally proved under security model. The security model of the quantum proxy signatures is helpful for analyzing and improving the security of the quantum proxy signature schemes. On the other hand, compared with the other quantum proxy signatures, the new one proposed in this paper is the first that can be formally proved to be secure under security model.
Most existing forward secure proxy signature schemes are constructed based on traditional number theory problems,such as large integer decomposition,discrete logarithm and bilinear pairs,and they are easy to be cracked in a quantum computing environment.In order to deal with the threat of quantum computing environment and reduce the risk of secret key leakage in proxy signature,an identity-based forward secure proxy signature scheme with NTRU lattice is constructed.Introduce forward secure features into the proxy signature over the lattice.Under the random prediction model,the security of the program is converted to the intractability of SIS,and a detailed efficiency analysis is also given.Analysis results show that the scheme realizes forward secrecy and strong non-repudiation,and it is verifiable and strongly identifiable.The computing efficiency is also improved as a result of the shortened signature key of the proxy signer,and shortened signature and signature key of the original signer.
Position-based cryptography has attracted lots of researchers' attentions. In mobile Internet, there are lots of position based security applications. For the first time, one new conception, position-based proxy signcryption is proposed. Based on a secure positioning protocol, one model of position-based proxy signcryption is proposed. In the model, positioning protocol is tightly bound to proxy signcryption, not loosely. Further, we propose one concrete position-based proxy signcryption scheme, its correctness is proved, and its security is also analyzed. As far as we know, it is the first position-based proxy signcryption scheme.
In a proxy signature scheme, an original signer delegates his/her signing capability to a proxy signer and then the proxy signer can sign messages on behalf of the original signer. The security of many proxy signature schemes that have been proposed depends, either directly or indirectly, on either the difficulty of big integers factoring problem or the difficulty of finding discrete logarithm in a finite group. These types of schemes cannot resist quantum attacks. In this paper, we propose a new lattice-based proxy signature scheme which can resist quantum attacks. The proposed scheme is based on the GGH-signature scheme and also satisfies all the security requirements of proxy signature schemes.