An efficient pairing-free certificateless signcryption scheme with public verifiability

In recent years, secure communication and privacy‐preserving are gaining popularity because of the advent of wireless network. Certificateless cryptography (CLC) and identity‐based cryptography (IBC) have already been widely applied in the area of wireless network. Hence, to achieve secure communication from CLC to IBC, we present a heterogeneous signcryption scheme that enables a sender in the CLC to transmit a message to multi‐receiver in the IBC. Our scheme has no restrictions on the system parameters and master keys; private key generator and key generating center generate their own system parameters and master key for the IBC users and the CLC user, separately. Considering privacy‐preserving in heterogeneous communication, we show that our scheme can realize the anonymity of all receivers. Compared with other schemes, our scheme has more advantages, such as public verification and decryption fairness, which are attractive for wireless network applications. Moreover, our scheme has the indistinguishability against adaptive chosen ciphertext attacks, the existential unforgeability against adaptive chosen messages attacks, and anonymous indistinguishability of encryptions under selective‐ID, chosen ciphertext attack in the random oracle model. Copyright © 2016 John Wiley & Sons, Ltd.

The notion of certificateless cryptography is aimed to eliminate the use of certificates in traditional public key cryptography and also to solve the key-escrow problem in identity-based cryptography. Many kinds of security models have been designed for certificateless cryptography and many new schemes have been introduced based on the correspondence of the security models. In generally speaking, a stronger security model can ensure a certificateless cryptosystem with a higher security level, but a realistic model can lead to a more efficient scheme. In this paper, we focus on the efficiency of a certificateless signature (CLS) scheme and introduce an efficient CLS scheme with short signature size. On one hand, the security of the scheme is based on a realistic model. In this model, an adversary is not allowed to get any valid signature under false public keys. On the other hand, our scheme is as efficient as BLS short signature scheme in both communication and computation and, therefore, turns out to be more efficient than other CLS schemes proposed so far. We provide a rigorous security proof of our scheme in the random oracle model. The security of our scheme is based on the k-CAA hard problem and a new discovered hard problem, namely the modified k-CAA problem. Our scheme can be applied to systems where signatures are typed in by human or systems with low-bandwidth channels and/or low-computation power.

Very recently, Karati et al. presented a new generalized CLSC (gCLSC) to provide the functions of digital signature and encryption to fulfill the authenticity and confidentiality for the resource-constrained Internet-of-Things (IoT) devices. Karati et al. claimed that the newly proposed gCLSC supports the property of public verifiability and security of an ideal signcryption under the strong Diffie–Hellman and bilinear Diffie–Hellman inversion problems without the random oracle model. Unfortunately, their scheme is insecure with respect to unforgeability. It is demonstrated that any receiver or nonprivileged user can generate a valid signature or signcrypted ciphertext on any message. Finally, this article also points out the flaw in their unforgeability proof and gives some suggestions on the construction of a concrete scheme.

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.

Boyen [7] gave the first identity-based (ID-based) signcryption scheme that is forward secure, publicly verifiable as well as provably secure. However, his scheme aims at providing ciphertext unlinkability and anonymity which is not a desirable property in applications such as authentication of encrypted messages by firewalls [11], where any third party should be able to verify the origin of the ciphertext without knowing the content of the message and getting any help from the intended recipient. This requirement is referred as public ciphertext authenticity. In this paper, we give another ID-based signcryption scheme that can provide public ciphertext authenticity and is forward and provably secure as well as publicly verifiable. Our scheme is modified from Libert and Quisquater’s ID-based signcryption scheme [16] and the efficiency of our scheme is comparable to other previous ID-based signcryption schemes.KeywordsIdentity-based signcryptionforward securitypublic verifiabilityprovable securitysemantical securitypublic ciphertext authenticitynetwork securityfirewallspublic key cryptosystemselliptic curve cryptosystemscryptographic primitives

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.

One of the main lines of research in functional encryption (FE) has consisted in studying the security notions for FE and their achievability. This study was initiated by [Boneh et al. – TCC’11, O’Neill – ePrint’10] where it was first shown that for FE the indistinguishability-based (IND) security notion is not sufficient in the sense that there are FE schemes that are provably IND-Secure but concretely insecure. For this reason, researchers investigated the achievability of Simulation-based (SIM) security, a stronger notion of security. Unfortunately, the above-mentioned works and others [e.g., Agrawal et al. – CRYPTO’13] have shown strong impossibility results for SIM-Security. One way to overcome these impossibility results was first suggested in the work of Boneh et al. where it was shown how to construct, in the Random Oracle (RO) model, SIM-Secure FE for restricted functionalities and was asked the generalization to more complex functionalities as a challenging problem in the area. Subsequently, [De Caro et al. – CRYPTO’13] proposed a candidate construction of SIM-Secure FE for all circuits in the RO model assuming the existence of an IND-Secure FE scheme for circuits with RO gates. To our knowledge there are no proposed candidate IND-Secure FE schemes for circuits with RO gates and they seem unlikely to exist. We propose the first constructions of SIM-Secure FE schemes in the RO model that overcome the current impossibility results in different settings. We can do that because we resort to the two following models: Both results also assume the RO model, but not functionalities with RO gates and rely on extractability obfuscation [Boyle et al. – TCC’14] (and other standard primitives) secure only in the standard model.

In this paper, we study strong designated verifier signature in certificateless public key settings. We first present the notion and security model of certificatless strong designated verifier signature (CLSDVS) scheme, and then, we provide a concrete CLSDVS scheme, which has short signature size and low computational cost, satisfies all the requirements of strong designated verifier signature. The scheme is proven secure in the random oracle model by assuming the intractability of the Computational Bilinear Diffie-Hellman Problem and the Computational Diffie-Hellman Problem.

Certificateless aggregate signcryption: Security model and a concrete construction secure in the random oracle model

PCAS: Cryptanalysis and improvement of pairing-free certificateless aggregate signature scheme with conditional privacy-preserving for VANETs

Signcryption was first proposed by Zheng and there after several signcryption schemes have been formulated. The broadcast scheme for Zheng does not offer non repudiation using public verification. A latest research by Elkamchouchi et. al proposed a new signcryption scheme for the broadcast environment. The scheme is known as Signcryption Multiple-Recipients Variant (SMRV). From the detail analysis of the scheme, it is observed that confidentiality of the information is lost when the parameters are sent to the third party for verification. Thus the scheme violates the basic property of security. Upon further analysis it is seen that the computational cost of the scheme can be reduced by eliminating few unnecessary steps which do not strengthen the security of the scheme but introduces an extra computational cost. In this paper an efficient and improved signcryption scheme for the broadcast environment is presented. The presented scheme is more efficient than Zheng's and Elkamchouchi et. al scheme in terms of computational cost. The scheme offers non repudiation through public verification and confidentiality of the information is also ensured.

Confidentiality and authenticity are two fundamental security requirement of Public key Cryptography. These are achieved by encryption scheme and digital signatures respectively. Wireless sensor networks are commonly used for critical security tasks such as intrusion or tamper detection, and therefore must be protected. The article proposes a provable secure signcryption scheme in Random oracle model for wireless security. It enables nodes to authenticate each other by keeping the information confidential. Also achieve data integrity in the communication. Security of the scheme is based on q-Diffie Hellman Problem. We modify the scheme proposed by Libert et al. and proposed a provably secure scheme with respect to security under assumptions of Strong Diffie-Hellman (SDH) and Diffie-Hellman Inversion (DHI) in the random oracles.

Internet of Drones (IoD) is considered as a network and management architecture, which can enable unmanned aerial vehicles (UAVs) to collect data in controlled areas and conduct access control for UAVs. However, the current cloud-assisted IoD scheme cannot efficiently achieve secure communication between heterogeneous cryptosystems, and does not support multi-ciphertext equality tests. To improve the security and performance of traditional schemes, we propose a heterogeneous signcryption scheme (HSC-MET) that supports multi-ciphertext equality test. In this paper, we use a multi-ciphertext equality test technique to achieve multi-user simultaneous retrieval of multiple ciphertexts safely and efficiently. In addition, we adopt heterogeneous signcryption technology to realize secure data communication from public key infrastructure (PKI) to certificateless cryptography (CLC). At the same time, the proposed scheme based on the computation without bilinear pairing, which greatly reduces the computational cost. According to the security and performance analysis, under the random oracle model (ROM), the confidentiality, unforgeability and number security of HSC-MET are proved based on the computational Diffie-Hellman (CDH) problem.

In this paper, we propose an elliptic curve-based signcryption scheme derived from the standardized signature KCDSA (Korean Certificate-based Digital Signature Algorithm) in the context of the Internet of Things. Our solution has several advantages. First, the scheme is provably secure in the random oracle model. Second, it provides the following security properties: outsider/insider confidentiality and unforgeability, non-repudiation and public verifiability, while being efficient in terms of communication and computation costs. Third, the scheme offers the certificateless feature, so certificates are not needed to verify the user's public keys. For illustration, we conducted experimental evaluation based on a sensor Wismote platform and compared the performance of the proposed scheme to concurrent schemes. We wish these experimental results be helpful at a larger extent to the scientific community usually prone to work with realistic performance figures.

ABSTRACTSecurity is a significant issue for ad-hoc networks. Heterogeneous signcryption schemes proposed in recent years satisfy privacy and authentication of messages and reduce cost of computation and communication in a logical step. In this article, we present a new efficient heterogeneous signcryption scheme that shifts between the public key infrastructure (PKI) and the identity-based cryptosystem (IBC). The proposed scheme is suitable for broadcast communication conditions in which senders can signcrypt multiple messages for multiple receivers simultaneously in the ad-hoc networks. This scheme is proved to satisfy confidentiality and unforgeability on the basis of the assumptions of bilinear Diffie-Hellman problem (BDHP), q-Diffie-Hellman inversion problem (q-DHIP), q-bilinear Diffie-Hellman inversion problem (q-BDHIP), and computational Diffie-Hellman problem (CDHP) in the random oracle model. We discuss the efficiency of our scheme theoretically. In the efficiency analysis phase, we show that our scheme is practical and efficient. In the performance analysis phase, we present additional tests, data, and explanations to prove that our scheme can be applied in ad-hoc networks. Finally, we apply our scheme to a simulated ad-hoc network.