Certificateless Cryptography Research Articles

On the Security of Certificateless Signature Schemes

Wireless Sensor Network (WSN) has proved its presence in various real time applications and hence the security of such embedded devices is a vital issue. Certificateless cryptography is one of the recent paradigms to provide security. Certificateless public key cryptography (CL-PKC) deals effectively with the twin issues of certificate management in traditional public key cryptography and key escrow problem in identity-based cryptography. CL-PKC has attracted special attention in the field of information security as it has opened new avenues for improvement in the present security architecture. Recently, Tsai et al. proposed an improved certificateless signature scheme without pairing and claimed that their new construction is secure against different kinds of attacks. In this paper, we present a security analysis of their scheme and our results show that scheme does not have resistance against malicious-KGC attack. In addition, we have found some security flaws in the certificateless signature scheme of Fan et al. and proved the scheme vulnerable to Strong Type I attack.

A Secure and Efficient Key Agreement Protocol Based on Certificateless Cryptography

Almost all the certificateless two-party authenticated key agreement (CTAKA) protocols found in the literature, suffer either serious security problems or inefficient performance that involves high computational costs. In this paper, we design a secure and efficient CTAKA protocol. Within the proposed CTAKA protocol, the KGC publishes the public keys of the users in a public directory (LDAP server) that has a certificate to prove its identity to the users. The LDAP certificate is the only existing certificate within the scheme. Both the two communicating parties are able to compute a common secret per session key using a secure generated random number. The protocol is fully secure against type 1 attack and fully secure against type 2 attacks under the assumptions that the KGC is an honest party and each party within the network has the full capability to keep its secret values safe. Moreover, the setup of the protocol does not include pairings and the whole key agreement process requires only four point scalar multiplications, two point additions, one hash function evaluation and one message exchange.

A Secure Routing Protocol Based on Certificateless Signcryption for Satellite Networks

The article introduces a certificateless signcryption scheme targeting the problem of lacking of security mechanism in the routing of satellite networks, and designs a secure routing protocol suitable for the satellite networks. The proposed protocol avoids complicated management in the certificate mechanism and bypasses the key escrow problem in the identity-based cryptography using the certificateless cryptography and signcryption. The analysis shows that the new protocol can resist several common attacks, effectively improve the security of the satellite networks routing.

Improved certificateless signature scheme provably secure in the standard model

Certificateless cryptography shares many features of identity-based cryptography and partially solves the problem of key escrow. Three certificateless signature schemes without random oracles were found in the literature. However, all the schemes suffer from some common drawbacks. First, by obtaining a signature on a message and replacing the public key of a signer, an adversary can forge valid signatures on the same message under the replaced public key. Secondly, all the schemes require a relatively large size of public parameters. The authors propose a new certificateless signature scheme, which exhibits an improvement on the existing schemes. Compared with the previous schemes, the proposed scheme offers stronger security, shorter system parameters and higher computational efficiency.

Certificateless message recovery signatures providing girault’s level-3 security

A digital signature with message recovery is a signature that the message itself (or partial of the message) is not required to be transmitted together with the signature. It has the advantage of small data size of communication comparing with the traditional digital signatures. In this paper, combining both advantages of the message recovery signatures and the certificateless cryptography, we propose the first certificatelss signature scheme with message recovery. The remarkable feature of our scheme is that it can achieve Girault’s Level-3 security while the conventional certificateless signature scheme only achieves Level-2 security. The security of the scheme is rigorously proved in the random oracle model based on the hardness of the k bilinear Diffie-Hellman inverse (k-BDHI) problem.

On the Security of a Certificateless Aggregate Signature Scheme

Certificateless cryptography eliminates the need of certificates in public key cryptosystems and solves the inherent key escrow problem in identity-based cryptosystems. An aggregate signature scheme is a signature scheme which allows to aggregate n signatures on n distinct messages from n distinct users into a single signature. Recently, Zhang and Zhang proposed a certificateless aggregate signature scheme provably secure in the random oracle model under the Computational Diffie-Hellman assumption. In this paper, we propose a novel fundamental security requirement for certificateless aggregate signature schemes, called coalition resistance, by presenting coalition attacks on Zhang-Zhang's scheme.

Efficient three-party authenticated key agreement protocol in certificateless cryptography

Key agreement protocols are multi-party protocols in which entities exchange public information allowing them to create a common secret key that is known only to those entities and which cannot be predetermined by any party. Key agreement can be achieved using a public key infrastructure or identity-based cryptography. However, the former suffers from a heavy certificate management burden, while the latter is subject to the so-called key escrow problem. Recently, the notion of certificateless public key cryptography (CL-PKC) was introduced to mitigate these limitations. In this paper, we introduce the notion of three-party authenticated key agreement into CL-PKC and propose a concrete certificateless three-party authenticated key agreement protocol. We show that the proposed protocol is secure (i.e. conforms to defined security attributes) while being efficient.

무인증서 공개키 암호에 기반한 다중수신자 암호 기법 및 응용

본 논문에서는 신원기반 다중수신자 암호 기법의 장점인 묵시적 인증을 제공하는 동시에 키 위탁문제를 해결하기 위한 무인증서 공개키 암호 기술 기반의 새로운 다중수신자 암호 기법을 소개한다. 제안 기법은 다중수신자에 대한 메시지 암호화 단계에서 겹선형 페어링 연산을 제거하였을 뿐만 아니라 복호화 단계에서 단 한 번의 겹선형 페어링 연산만을 요구하는 매우 효율적인 다중수신자 암호 기법이다. 또한, 본 논문에서는 제안 기법을 이용하여 스테이트리스 수신자 환경을 위한 서브셋-커버 프레임워크 기반의 새로운 공개키 브로드캐스트 암호 기법을 제시한다. In this paper we introduce the notion of multi-receiver certificateless encryption that avoids the inherent key escrow problem of multi-receiver identity-based encryption, and also present a highly efficient multi-receiver certificateless encryption scheme which eliminates pairing computation to encrypt a message for multiple receivers, Moreover, the proposed scheme only needs one pairing computation to decrypt the ciphertext. Finally, we discuss how to properly transform our scheme into a new public key broadcast encryption scheme for stateless receivers based on the subset-cover framework, which enjoys the advantages of certificateless cryptography.

Certificateless cryptography with KGC trust level 3

A normal certificateless cryptosystem can only achieve KGC trust level 2 according to the trust hierarchy defined by Girault. Although in the seminal paper introducing certificateless cryptography, Al-Riyami and Paterson introduced a binding technique to lift the KGC trust level of their certificateless schemes to level 3, many subsequent work on certificateless cryptography just focused on the constructions of normal certificateless schemes, and a formal study on the general applicability of the binding technique to these existing schemes is still missing. In this paper, to address the KGC trust level issue, we introduce the notion of Key Dependent Certificateless Cryptography (KD-CLC). Compared with conventional certificateless cryptography, KD-CLC can achieve stronger security, and more importantly, KGC trust level 3. We then study generic techniques for transforming conventional CLC to KD-CLC. We start with the binding technique by Al-Riyami and Paterson, and show that there are some technical difficulties in proving that the binding technique is generally applicable. However, we show that a slightly modified version of the binding technique indeed can be proved to work under the random oracle assumption. Finally, we show how to perform the transformation using a standard cryptographic primitive instead of a random oracle.

A Secure Protocol for Sharing Trust Data in Hybrid P2P Network

The trust data is critical to the trust model of P2P system. In this paper we present an efficient certificateless cryptography scheme and propose a protocol which provides the ability for sharing trust data securely. The protocol avoids the escrow problem identity-based cryptosystem and the secure delivery of private keys. The security of scheme is based on some underlying problems closely related to the Bilinear Diffie-Hellman Problem are computationally hard. It tolerates the Type I and Type II adversary. The proof of security is presented in the random oracle model. Through security discussion, we show that my secure protocol is extremely secure when encounter a variety of possible attacks.

A Certificateless Proxy Ring Signature Scheme with Provable Security

Proxy ring signature allows proxy signer to sign messages on behalf of the original signer while providing anonymity. Certificateless public key cryptography was first introduced by Al-Riyami and Paterson in Asiacrypt 2003. In certificateless cryptography, it does not require the use of certificates to guarantee the authenticity of users' public keys. Meanwhile, certificateless cryptography does not have the key escrow problem, which seems to be inherent in the Identity-based cryptography. In this paper, we introduce the notion of proxy ring signature into certificateless public key cryptography and propose a concrete certificateless proxy ring signature scheme. The security models of certificateless proxy ring signature are also formalized. The security of the proposed scheme can be proved to be equivalent to the computational Diffe-Hellman problem in the random oracle with a tight reduction.

Secret Key-Awareness Secure in Certificateless Cryptography

Abstract In certificateless cryptography protocol, public keys don’t be required certificates to guarantee their validity, so any other adversaries can replace users’ public keys. There are two security models: the weak security model prohibits the adversaries to query the decryption oracle of the ciphertexts under the public key chosen by the adversaries, and the more strong security model is asked to correctly answer the decryption oracle of this type of ciphertexts. As we well known, almost all certificateless cryptography protocols secure in the strong model are at the cost of the efficiency. In this paper, we introduce a new definition of secret key awareness security, and we can show a protocol secure in a weak security model is also secure in the strong security model, if it satisfies secret key awareness security simultaneously. We also give a concrete certificateless scheme secure in the strong security model.

On the Existence of Short Certificateless Signatures

Certificateless cryptography eliminates the need of certificates in public key cryptosystems and solves the inherent key escrow problem in identity-based cryptosystems. In this paper we discuss the existence of short certificateless signature schemes provably secure in formal security models recently established, whose resulting signature consists of a single element of the underlying group by demonstrating key replacement attacks on Du-Wen's and Tso et al.'s short certificateless signature schemes.

Cryptanalysis on Two Certificateless Signature Schemes

Certificateless cryptography has attracted a lot of attention from the research community, due to its applicability in information security. In this paper, we analyze two recently proposed certificateless signature schemes and point out their security flaws. In particular, we demonstrate universal forgeries against these schemes with known message attacks.

Certificateless threshold signature secure in the standard model

Threshold signature is an extension of the standard signature, in which several signers may be required to cooperatively sign messages for sharing the responsibility and authority. Certificateless cryptography eliminates the need of certificates in the Public Key Infrastructure and solves the inherent key-escrow problem in the Identity-based (ID-based) cryptography. In this paper, we propose a certificateless threshold signature scheme with concrete implementation which is provably secure in the standard model. Furthermore, this scheme is proven secure against the malicious-but-passive KGC attack. To the best of author’s knowledge, this is the first construction of certificateless threshold signature scheme that does not rely on random oracle or ideal ciphers.

Efficient many-to-one authentication with certificateless aggregate signatures

Aggregate signatures allow an efficient algorithm to aggregate n signatures of n distinct messages from n different users into one single signature. The resulting aggregate signature can convince a verifier that the n users did indeed sign the n messages. This feature is very attractive for authentications in bandwidth-limited applications such as reverse multicasts and senor networks. Certificateless public key cryptography enables a similar functionality of public key infrastructure (PKI) and identity (ID) based cryptography without suffering from complicated certificate management in PKI or secret key escrow problem in ID-based cryptography. In this paper, we present a new efficient certificateless aggregate signature scheme which has the advantages of both aggregate signatures and certificateless cryptography. The scheme is proven existentially unforgeable against adaptive chosen-message attacks under the standard computational Diffie-Hellman assumption. Our scheme is also very efficient in both communication and computation and the proposal is practical for many-to-one authentication.

Efficient and short certificateless signatures secure against realistic adversaries

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.

A Provably Secure Proxy Signature Scheme in Certificateless Cryptography

A proxy signature scheme enables an original signer to delegate its signing capability to a proxy signer and then the proxy signer can sign a message on behalf of the original signer. Recently, in ...

A Provably Secure Proxy Signature Scheme in Certificateless Cryptography

A proxy signature scheme enables an original signer to delegate its signing capability to a proxy signer and then the proxy signer can sign a message on behalf of the original signer. Recently, in order to eliminate the use of certificates in certified public key cryptography and the key-escrow problem in identity-based cryptography, the notion of certificateless public key cryptography was introduced. In this paper, we first present a security model for certificateless proxy signature schemes, and then propose an efficient construction based on bilinear pairings. The security of the proposed scheme can be proved to be equivalent to the computational Diffie-Hellman problem in the random oracle with a tight reduction.

Certificateless key-insulated signature without random oracles

Leakage of the private key has become a serious problem of menacing the cryptosystem security. To reduce the underlying danger induced by private key leakage, Dodis et al.(2003) proposed the first key-insulated signature scheme. To handle issues concerning the private key leakage in certificateless signature schemes, we devise the first certificateless key-insulated signature scheme. Our scheme applies the key-insulated mechanism to certificateless cryptography, one with neither certificate nor key escrow. We incorporate Waters (2005)’s signature scheme, Paterson and Schuldt (2006)’s identity-based signature scheme, and Liu et al.(2007)’s certificateless signature scheme to obtain a certificateless key-insulated signature scheme. Our scheme has two desirable properties. First, its security can be proved under the non-pairing-based generalized bilinear Diffie-Hellman (NGBDH) conjecture, without utilizing the random oracle model; second, it solves the key escrow problem in identity-based key-insulated signatures.