Two Proxy Signcryption Schemes from Bilinear Pairings

Proxy signcryption is a novel cryptographic primitive that combines the functionality of a proxy signature with that of a signcryption. However, the security of all the known proxy signcryption schemes were proven in the random oracle, which has received a lot of criticism that the proofs in the random oracle model are not sound with respect to the standard model. Hence, it is an interesting research problem on how to construct a provably secure proxy signcryption scheme in the standard model. In this paper, motivated by Waters' signature scheme, we propose a new construction of proxy signcryption scheme based on bilinear pairing without using random oracles. Then, we use the techniques from provable security to show that the proposed scheme is indistinguishability under adaptive chosen ciphertext attacks secure under the decisional bilinear Diffie–Hellman assumption and existentially unforgeable under the computational Diffie–Hellman assumptions. Compared with the existing schemes with formal security proof, we show that no pairing computation is required in our proxy signcrypt phase with pre‐computations. To the best of our knowledge, our proposed scheme is the first provably secure proxy signcryption scheme in the standard model. Copyright © 2014 John Wiley & Sons, Ltd.

Signcryption is a cryptographic primitive that performs encryption and signature in a single logical step, at lower computational cost and communication over heads than the signature-then-encryption. Proxy signcryption schemes are variations of ordinary signcryption schemes and have been useful in many applications where the delegation of rights is quite common. By combining the functionalities of proxy signature scheme and signcryption scheme, in this paper, we proposed a new ID-based proxy signcryption scheme which offers both public verifiability and forward security. The security requirements and performance of the proposed scheme are analyzed.

Certificateless cryptography introduced by Al-Riyami and Paterson eliminates the key escrow problem inherent in identity based cryptosystems. Even though building practical identity based signcryption schemes without bilinear pairing are considered to be almost impossible, it will be interesting to explore possibilities of constructing such systems in other settings like certificateless cryptography. Often for practical systems, bilinear pairings are considered to induce computational overhead. Signcryption is a powerful primitive that offers both confidentiality and authenticity to noteworthy messages. Though some prior attempts were made for designing certificateless signcryption schemes, almost all the known ones have security weaknesses. Specifically, in this paper we demonstrate the security weakness of the schemes in [2], [1] and [6]. We also present the first provably secure certificateless signcryption scheme without bilinear pairing and prove it in the random oracle model.

Digital signature with proxy delegation, which is a secure ownership enforcement tool, allows an original signer to delegate signature rights to a third party called proxy, so that the proxy can sign messages on behalf of the original signer. In today’s modern society, many applications use this mechanism. Several types of delegations are quite prevalent and the delegation of signing authority is one of them. In a traditional digital signature scheme, signer transmits signature along with message for verification, which leads to additional communication, computation cost and requires extra bandwidth. To resolve these issues, in this paper, we present an efficient ID-based proxy signature scheme with message recovery using bilinear pairings. Because of the message recovery feature, the proxy signer need not send the message to the verifier, so that the proposed scheme reduces the bandwidth requirement and communication cost. Our proposed scheme is proven secure against existential forgery under adaptively chosen message and identity attacks in the random oracle model (ROM) with the assumption that the Computational Diffie-Hellman Problem (CDHP) is intractable. We compare our scheme with related schemes. The efficiency analysis shows that the scheme is computationally efficient. Thus the proposed ID-based proxy signature scheme is secure and efficient both in terms of computation and communication costs than the related existing schemes.

Signcryption is a cryptographic technique that provides both confidentiality and authenticity of data during public transmission in many modern applications like Internet -of -Things (IoT), Wireless Sensor Networks (WSNs) etc. The functionalities of encryption and Signature can achieve simultaneously through the signcryption with lower computational cost and communication overheads than those of traditional sign-then-encrypt approach. Many signcryption schemes have been constructed by various researchers in different cryptographic frameworks. Certificateless cryptography is one of the recent public key cryptography which eliminates the key escrow problem and complex certificate management problemsin identity based cryptography and traditional public key cryptography respectively. Providing the security and efficiency in many modern applications including IoT and WSNs is a crucial task. In this paper, we proposed new signcryption scheme in certificateless cryptography. This scheme supports the property of public verifiability and is secure against various types of adversaries in the random oracle model with the assumption that the Computational Diffie-Hellman Problem (CDHP) and the Elliptic Curve Discrete Logarithmic Problems (ECDLP) are hard. Due to pairing-free environment the proposed scheme is computationally more efficient than the existing public verifiable signcryption schemes.

Generalized signcryption can adaptively work as an encryption scheme, a signature scheme, or a signcryption scheme with only one algorithm. The paper proposes an efficient certificateless generic signcryption scheme without utilizing bilinear pairing operations. It is proved to satisfy confidentiality and unforgeability against chosen ciphertext and message attacks in an adaptive manner, respectively, in the random oracle model. Due to the lower computational cost and communication overhead, the proposed scheme is suitable for low power and processor devices.

An Authentication and Key Agreement Mechanism for Multi-Domain Wireless Networks using Bilinear Pairings

This paper designs a secure identity-based threshold signcryption scheme from the bilinear pairings. The construction is based on the recently proposed signcryption scheme of Libert and Quisquater [6]. Our scheme not only has the properties of identity-based and threshold, but also can achieve semantic security under the Decisional Bilinear Diffie-Hellman assumption. It can be proved secure against forgery under chosen message attack in the random oracle model. In the private key distribution protocol, we adopt such method that the private key associated with an identity rather than the master key is shared. In the threshold signcryption phase, we provide a new method to check the malicious members. This is the first identity-based threshold signcryption scheme that can simultaneously achieve both semantic security and others security, such as unforgeability, robustness, and non-repudiation.

Certificateless public key infrastructure (PKI) avoids the key escrow problem associated with identity-based PKI and has recently been widely employed in anonymous communication schemes for vehicular adhoc networks (VANETs). In existing certificateless anonymous signcryption schemes for VANETs, vulnerabilities such as potential attacks involving the substitution of pseudonyms and the forging of pseudonymous public-private key pairs exist due to the lack of “identity-key binding” and “non-linearity processing of public-private key pairs.” To address this issue, we propose an improved certificateless anonymous signcryption scheme based on elliptic curve cryptography. The scheme incorporates bilinear pairing as one of the authentication mechanisms, designs pseudonym generation algorithms and public-private key pair structures, and introduces a pseudonym verification mechanism. The correctness of the scheme is proven under the random oracle model, and its security is extensively demonstrated through detailed discussions on its confidentiality, authentication, unforgeability, anonymity, and traceability. Furthermore, the time and space complexity of the scheme are calculated. By comparing with recently published certificateless signcryption schemes, it is shown that the proposed scheme offers higher security with smaller computational and communication overheads. This certificateless vehicular network signcryption algorithm provides an efficient encryption solution for anonymous communication in vehicular networks, thereby ensuring the rapid development of secure technology for intelligent connected vehicle super terminals.

As a variation of ordinary digital signature scheme, a proxy signature scheme enables a proxy signer to sign messages on behalf of the original signer. Proxy multi-signature is an extension of the basic proxy signature primitive, and permits two or more entities to delegate their signing capabilities to some other entity. Many identity-based proxy multi signature (IBPMS) schemes using bilinear pairings have been proposed. But the relative computation cost of the pairing is approximately more than ten times of the scalar multiplication over elliptic curve group. In order to save the running time and the size of the signature, in this paper, we propose an IBPMS scheme without bilinear pairings. We also prove the security of our scheme against adaptive chosen message attack under random oracle model. With the running time being saved greatly, our scheme is more applicable than the previous related schemes for practical applications.KeywordsDigital signatureIdentity-based cryptographyProxy-multi signatureElliptic curve discrete log problem

Recently, the notion of the key-insulated public- key system has been suggested to protect the security of users' private keys. A general idea of this system is changing the user's private key along with the time, but the user's public key remains unchanged. In this paper, we propose a new identity (ID)-based key-insulated signature scheme from bilinear pairings. As compared with the recently proposed ID-based key-insulated signature schemes, our proposed scheme has better performance in the batch verifying phase. For security analysis, our scheme is a provably secure key-insulated signature scheme in the random oracle model and under the computational Diffie-Hellman assumption. Meanwhile, to demonstrate the additional advantage of a key-insulated signature, we present a novel application based on the proposed scheme, called full delegation ID-based proxy signature scheme with time restriction. To our best knowledge, no such a proxy signature scheme is proposed until now.

The concept of policy-based cryptography is a promising paradigm for trust establishment and authorization in largescale open environments like the Internet and Mobile Networks. It aims at providing a framework for performing cryptographic operations with respect to policies formalized as monotone Boolean expressions written in standard normal forms. A policy involves conjunctions and disjunctions of conditions where each condition is fulfilled by a digital credential representing the signature of a specific credential issuer on a set of statements about a certain entity. Therefore, an entity fulfills a policy if any only if it has been issued a set of credentials fulfilling the combination of conditions specified by the policy.In this work, we focus on policy-based encryption schemes which allow to encrypt a message according to a policy so that only entities fulfilling the policy are able to decrypt the message. More generally, policy-based encryption belongs to an emerging family of encryption schemes sharing the ability to integrate encryption with access control structures. This ability is mainly enabled by bilinear pairings over elliptic curves and allows for several interesting applications in different contexts.A policy-based encryption scheme has to fulfill two primary requirements: on one hand, provable security under well defined attack models. On the other hand, efficiency, especially when dealing with the conjunctions and disjunctions of credential-based conditions.The contributions of our research work are twofold:1. The standard acceptable notion of security for public-key encryption schemes is indistinguishability against chosen ciphertext attacks. Hence, it is natural to require that a policy-based encryption scheme also satisfies this strong notion of security. However, the definition of this security notion must be adapted to the policy-based setting. Our first contribution is the definition of policy-oriented security model for policy-based encryption schemes as well as the development of an efficient policy-based encryption scheme that is provably secure under our security model in the random oracle model.2. Policy-based encryption schemes may suffer from the key-escrow property i.e. in addition to the legitimate holder of the credentials fulfilling the encryption policy, any collusion of credential issuers who are able to issue a set of credentials fulfilling the policy can decrypt the message. Our second contribution is to address this issue through the notion of policy-based public-key encryption. The latter allows encrypting a message not only with respect to a policy but also according to a public-key so that only an entity fulfilling the policy and having access to the corresponding private-key is able to decrypt the message. We developed a policy-based public-key encryption scheme from bilinear pairings and proved its security under the corresponding security model. Our proposal improves related work in terms of both security and efficiency.

With ever growing popularity, wireless communication system also vulnerable to various security attacks. To provide high level security, many cryptographic solutions have been proposed. One such solution is signcryption, where authenticity and confidentiality provided by single logical step. Therefore, signcryption scheme helps to reduce computational cost, but it is not feasible for resource constraint environments. Because, most of the existing approaches were based on El-Gamal, bilinear pairing, Rivest-Shamir-Adleman (RSA), and Elliptic curve Cryptography (ECC). They consume more energy due to their increased key size. Hence, the new signcryption approach is proposed based on Hyper Elliptic Curve Cryptosystem (HECC) whose key size is much lesser than ECC. It significantly reduces the cost of computation and communication overhead by half the amount of ECC which suits well for resource constraint environments. Further, the proposed scheme attains necessary security features along with forward secrecy and public verifiability. On the other hand, the security of the approach is validated through an automated protocol validation tool – AVISPA.

In this paper, we first construct a security model for delegation-by-warrant ID-based proxy signcryption schemes and formalize notions of security for them. To the best of our knowledge, no related work has been done. Then we present such a scheme based on the bilinear pairings, and show that it is provably secure in the random oracle model. Specifically, we prove its semantic security under the DBDH assumption and its unforgeability under the BDH assumption.

Signcryption is a cryptographic primitive which simultaneously provides both confidentiality and authenticity in a single logical step. In a proxy signature scheme, an original signer delegates his signing power to a proxy agent, who signs a message on behalf of him. This paper introduces a new proxy signcryption scheme based on the Discrete Logarithm Problem (DLP) with a reduced computational complexity compared to other schemes in literature. In this proposed scheme, the receiver is the only one who can verify the origin of the ciphertext. Moreover, in this scheme, an authorized proxy signcrypter can create valid proxy signatures after verifying the identity of the original signcrypter. The proposed scheme achieves the various desirable security requirements. An elliptic curve based version of the proposed proxy signcryption scheme has been implemented using Mathematica for realistic (256-bit) parameters to emphasize the ease of its practical use.