Proxy signcryption means that the proxy signcrypter obtains the delegate authorization from the original signcrypter and then signcrypts the specified message on behalf of the original signcrypter. In this paper, we construct an identity-based proxy signcryption protocol (IBPSP) based on the universally composable (UC) framework. In the random oracle model, we prove that this protocol has the semantic security under the gap bilinear Diffie-Hellman and computational Diffie-Hellman assumptions. At the same time, an ideal functionality of the identity-based proxy signcryption protocol is defined in the UC security framework, and we also prove the equivalence between the universally composable identity-based proxy signcryption protocol and its IND-CCA2 and UF-CMA security. Analysis shows this IBPSP has both low computation complexity and semantic security together with UC security.
Proxy signcryption means that the proxy signcrypter obtains the delegate authorization from the original signcrypter and then signcrypts the specified message on behalf of the original signcrypter. In this paper, we construct an identity-based proxy signcryption protocol (IBPSP) based on the universally composable (UC) framework. In the random oracle model, we prove that this protocol has the semantic security under the gap bilinear Diffie-Hellman and computational Diffie-Hellman assumptions. At the same time, an ideal functionality of the identity-based proxy signcryption protocol is defined in the UC security framework, and we also prove the equivalence between the universally composable identity-based proxy signcryption protocol and its IND-CCA2 and UF-CMA security. Analysis shows this IBPSP has both low computation complexity and semantic security together with UC security.
Proxy-signcryption is a variation of an ordinary signcryption scheme and has been used in many applications where the delegation of rights is quite common. In a proxy-signcryption scheme, an original signcrypter needs to delegate his signcryption capability to a proxy signcrypter to signcrypt messages on behalf of the original signcrypter. By combining the functionalities of proxy signature with identity-based signcryption, in this paper, we propose a novel identity-based proxy-signcryption scheme (IBPSC) from lattice assumptions in the random oracle model. Meanwhile, the security requirements of our IBPSC scheme have been analysed, and our scheme can even resist quantum computer attacks. Compared with existing IBPSC schemes, our scheme is more secure and more efficient. To the best of our knowledge, there is still no relevant IBPSC scheme based on lattice, which is an interesting stepping stone in the post-quantum cryptographic communication.
Identity-based encryption (IBE) is one of the most important primitives in cryptography, and various security notions of IBE (e. g., IND-ID-CCA2, NM-ID-CCA2, IND-sID-CPA etc.) have been introduced. The relations among them have been clarified recently. This paper, for the first time, investigates the security of IBE in the universally composable (UC) framework. This paper first defines the UC-security of IBE, i. e., we define the ideal functionality of IBE, FIBE. We then show that UC-secure IBE is equivalent to conventionally-secure (IND-ID-CCA2-secure) IBE.
Abstract. This paper analyzes group communication within the universally composable framework. We first propose the group communication model, identity-based signcrytion mod-el and group key distribution model in the UC framework by designing the ideal functionality FSAGCOM, FIDSC and FGKD, respectively. Then, we construct a UC secure identity-based signcryption protocol πIDSC. Moreover, we shows that the identity-based signcryption πIDSC securely realizes the ideal functionality FIDSC if and only if the corresponding protocol ID-SC is secure. Finally, based on the identity-based protocol, we propose a group communica-tion scheme πSAGCOM, which can securely realizes the ideal functionality FSAGCOM in the (FIDSC,FGKD)-hybrid model.
Idea Functionality is the core and basic unit of Universally Composable(UC) security protocols.The first step of designing the protocols,within the UCsecurity framework,is to extract an ideal functionality from the expected functionalities of the protocols.To appropriately define an ideal functionality we should not only protect the security of the definition,but also consider the realizability.This study investigates the security of identity-based signature(IBS) within the UCframework,defines a realizable identity-based signature functionality FIBS,proves that UC-secure IBS is equivalent to conventionally-secure(EUF-CMIA-secure) IBS.As a result,we are able to make sure that the EUFCMIA scheme can be a module in designing a complex protocol that satisfies the UCrequirement.
Proxy Re-Encryption was introduced by Blaze, Bleumer and Strauss to efficiently solve the problem of delegation of decryption rights. In proxy re-encryption, a semi-honest proxy transforms a ciphertext intended for Alice to a ciphertext of the same message for Bob without learning anything about the underlying message. From its introduction, several proxy re-encryption schemes in the Public Key In-frastructure (PKI) and Identity (ID) based setting have been proposed. In practice, systems in the public key infrastructure suffer from the certificate management problem and those in identity based setting suffer from the key escrow problem. Certificateless Proxy Re-encryption schemes enjoy the advantages provided by ID-based constructions without suffering from the key escrow problem. In this work, we construct the first unidirectional, single-hop CCA-secure certificateless proxy re-encryption scheme without pairing by extending the PKI based construction of Chow et al. proposed in 2010. We prove its security in the random oracle model under the Computational Diffie-Hellman (CDH) assumption. Prior to this work, the only secure certificateless proxy re-encryption scheme is due to Guo et al. proposed in 2013 using bilinear pairing. The construction proposed in this work is more efficient than that system and its security relies on more standard assumptions. We also show that the recently proposed construction of Yang et al. is insecure with respect to the security model considered in this work.
Proxy re-encryption, introduced by Blaze et al. in 1998, allows a proxy to transform a ciphertext computed under Alice's public key into one that can be opened under Bob's decryption key. An open problem of constructing (bidirectional or unidirectional) IND-PRE-CCA2 secure proxy re-encryption scheme in the standard model yet without pairings was left until now. In this paper, based on Hanaoka's efficient chosen ciphertext secure public key encryption under the computational Diffie-Hellman assumption, we try to solve this open problem by presenting two new bidirectional proxy re-encryption schemes, which are restricted IND-PRE-CCA2 secure without pairing nor random oracle.