New Blind Muti-signature Schemes based on ECDLP

In various types of electronic transactions, including election systems and digital cash schemes, user anonymity and authentication are always required. Blind signatures are considered the most important solutions to meeting these requirements. Many studies have focused on blind signature schemes; however, most of the studied schemes are single blind signature schemes. Although blind multi-signature schemes are available, few studies have focused on these schemes. In this article, blind multi-signature schemes are proposed based on the Elliptic Curve Discrete Logarithm Problem (ECDLP). The proposed schemes are based on the GOST R34.10-2012 digital signature standard and the EC-Schnorr digital signature scheme, and they satisfy blind multi-signature security requirements and have better computational performance than previously proposed schemes. The proposed schemes can be applied in election systems and digital cash schemes

Improved ciphertext-policy time using short elliptic curve Diffie–Hellman

Ciphertext-policy attribute-based encryption (CP-ABE) is a suitable solution for the protection of data privacy and security in cloud storage services. In a CP-ABE scheme which provides an access structure with a set of attributes, users can decrypt messages only if they receive a key with the desired attributes. As the number of attributes increases, the security measures are strengthened proportionately, and they can be applied to longer messages as well. The decryption of these ciphertexts also requires a large decryption key which may increase the decryption time. In this paper, we proposed a new method for improving the access time to the CP using a new elliptic curve that enables a short key size to be distributed to the users that allows them to use the defined attributes for encryption and decryption. Each user has a specially created key which uses the defined attributes for encryption and decryption based on the Diffie-Hellman method. After the implement, the results show that this system saves nearly half of the execution time for encryption and decryption compared to previous methods. This proposed system provides guaranteed security by means of the elliptic curve discrete logarithmic problem

Proxy Blind Multi-signature Scheme using ECC for handheld devices

A proxy blind signature scheme is a special form of blind signature which allowed a designated person called proxy signer to sign on behalf of two or more original signers without knowing the content of the message or document. It combines the advantages of proxy signature, blind signature and multi-signature scheme. This paper describes an e±cient proxy blind multi-signature scheme. The security of the proposed schemes is based on the di±culty of breaking the one-way hash function and the elliptic curve discrete logarithm problem (ECDLP). This can be implemented in low power and small processor handheld devices such as smart card, PDA etc which work in low power and small processor. This scheme utilizes a trusted third party called certificate authority to ensure that signatures can only be generated during valid delegation period. It satisfies the security properties of both proxy and blind signature scheme

Efficient and Provably-secure Certificateless Strong Designated Verifier Signature Scheme without Pairings

Strong designated verifier signature (generally abbreviated to SDVS) allows signers to obtain absolute control over who can verify the signature, while only the designated verifier other than anyone else can verify the validity of a SDVS without being able to transfer the conviction. Certificateless PKC has unique advantages comparing with certificate-based cryptosystems and identity-based PKC, without suffering from key escrow. Motivated by these attractive features, we propose a novel efficient CL-SDVS scheme without bilinear pairings or map-to-point hash operations. The proposed scheme achieves all the required security properties including EUF-CMA, non-transferability, strongness and non-delegatability. We also estimate the computational and communication efficiency. The comparison shows that our scheme outperforms all the previous CL-(S)DVS schemes. Furthermore, the crucial security properties of the CL-SDVS scheme are formally proved based on the intractability of SCDH and ECDL assumptions in random oracle model

A Certificate-Based Proxy Signature with Message Recovery without Bilinear Pairing

In this paper, we propose the first provable secure certificate-based proxy signature with message recovery without bilinear pairing. The notion of certificate-based cryptography was initially introduced by Gentry in 2003, in order to simplify certificate management in traditional public key cryptography(PKC)and to solve the key escrow problem in identity-based cryptosystems. To date, a number of certificate-based proxy signature(CBPS)schemes from bilinear pairing have been proposed. Nonetheless, the total computation cost of a pairing is higher than that of scalar multiplication(e.g., over elliptic curve group). Consequently, schemes without pairings would be more appealing in terms of efficiency. According to the available research in this regard, our scheme is the first provable secure CBPS scheme with message recovery which is based on the elliptic curve discrete logarithm problem. We prove the security of the presented scheme against existential forgery under adaptive chosen message and ID attacks in the random oracle model. Moreover, the paper will also show how it would be possible to convert this scheme to the CBPS scheme without message recovery. This scheme has more applications in situations with limited bandwidth and power-constrained devices

PFCBAS: pairing free and provable certificate-based aggregate signature scheme for the e-healthcare monitoring system

Recently, one of the most popular technologies of the modern era, the Internet of Things, allows the deployment and usage of various real-time test beds in various smart applications. One such application is the e-healthcare, in which patients' healthcare related data are transmitted to the nearest base station and then to a local or remote server as per the requirements. The data related to patients' health are sensitive and need special protection, therefore, the integrity and authentication of the sources of data generation are paramount concerns. However, several authentication or signature schemes that have been introduced in the past for this purpose are ID-based or having certificate-less settings. In these settings, a central authority, known as a trusted authority (TA), creates and distributes the secret key of every user. Thus, knowing the secrete key by the TA is called key escrow problem. But, these proposed schemes suffer from key distribution problems, which limit their applications in various applications. To mitigate these issues, this paper presents a certificate-based pairing free aggregate signature scheme (CBPFAS). The proposed scheme uses the merits of public key cryptography (PKC) and identity-based PKC (IDBPKC). The scheme is proven to be unforgeable, assuming the hardness of elliptic curve discrete log problem (ECDLP). The performance analysis shows that the proposed CBPFAS scheme executes in 0.78(n+1) ms in comparison to 9.63+1.17n ms in [1], 9.63+0.78n ms in [2], 9.63+3.39n ms in [3], and 9.63+1.17n ms in [4]. From these results, it is concluded that the proposed pairing free certificate-based aggregate signature scheme performs better than its counterparts

A Secure and Efficient Authentication Technique for Vehicular Ad-Hoc Networks

Vehicular ad-hoc networks (VANETs) have been emerging due to the recent technologies in wireless and network communications. The most fundamental part in VANETs is to enable message authentications between vehicles and roadside units. Message authentication using proxy vehicles has been proposed to reduce the computational overhead of roadside units significantly. In this type of message authentication schemes, proxy vehicles with verifying multiple messages at the same time improve computational efficiency of roadside units when there are a large number of vehicles in their coverage areas. In this paper, first we show that the only proxy-based authentication scheme (PBAS) presented for this goal by Liu et al. cannot achieve authenticity of messages, and also it is not resistant against impersonation and modification attacks and false acceptance of batching invalid signatures. Next, we propose a new identity based message authentication using proxy vehicles (ID-MAP). Then, to guarantee that it can satisfy message authentication requirement, existential unforgeability of underlying signature against adaptively chosen-message and identity attack is proved under Elliptic Curve Discrete Logarithm Problem in the random oracle model. It should be highlighted that ID-MAP not only is more efficient than PBAS since it is pairing-free and does not use map-to-point hash functions, but also it satisfies security and privacy requirements of vehicular ad hoc networks. Furthermore, analysis shows that the required time to verify 3000 messages in ID-MAP is reduced by 76% compared to that of PBAS

Signcryption schemes based on elliptic curve cryptography

Signcryption is cryptographic primitive which simultaneously provide both the function of digital signature and public key encryption in a single logical step. Identity based cryptography is an alternative to the traditional certificate based cryptosystem. Its main idea is that each user uses his identity information as his public key. Many identity based signcryption scheme have been proposed so, far. However, all the schemes were proven using bilinear pairing. Elliptic curve cryptosystem (ECC) have recently received significant attention by research due to their low computational and communicational overhead. Elliptic curve cryptography (ECC) is the hardest computational problems; the elliptic curve discrete logarithm problem and elliptic curve Deffie-Hellman problem are the most reliable cryptographic technique in ECC. The advantages of ECC that it requires shorter key length compared to other public-key algorithms. So, that its use in low-end systems such as smart cards because of its efficiency and limited computational and communicational overhead. We introduce new signcryption schemes based on elliptic curve cryptography. The security of proposed schemes is based on elliptic curve discrete logarithm problem (ECDLP) and elliptic curve Diffie-Hellman problem (ECDHP). The proposed schemes provide various desirable security requirements like confidentiality, authenticity, non-repudiation and forward security as well as chosen ciphertext attack and unforgeability