Blind Digital Signatures: Theory and Applications

Blind signature schemes, as important cryptographic primitives, are useful protocols that guarantee the anonymity of the participants. In this paper, a new blind signature based on the strong RSA assumption is presented. The new blind signature scheme is quite efficient and statefree. It does not require the signer to maintain any state and can be proven secure against adaptive chosen message attack under a reasonable tractability assumption, the so-called Strong RSA assumption. Moreover, a hash function can be incorporated in to the scheme in such a way that it is also secure in the random oracle model under the standard RSA assumption.

Blind signature is a variant of digital signature which helps the user to obtain a signature without giving any information about the message to the signer and the signer cannot tell which session of the signing protocol corresponds to which message. Blind signatures may seem to be a myth; it is a practical reality due to its wide applications in real life like e-coin and e-voting. This paper focuses on the study of variants of blind signatures with its eminent real world applications. It also discuses about future research scope of blind signatures.

International Journal of Computer Applications, 2013

Security of the consumer"s data over internet is the major problem in present time. In this paper we have analyzed blind signature schemes based on RSA and with taking advantage of elliptic curve cryptography to achieve the security goals. Blind signature scheme is one of the security protocol to obtain signature from a signer such that signer sign the message without reading the content of the message and also he could not link the protocol with the resulting message signature pair [7]. Blind signature scheme is used to achieve certain security goals like blindness, untraceability, authenticity, unforgeability [1]. We have analyzed blind signature scheme to achieve the security goals using Elliptic Curve Cryptosystem. Elliptic curve cryptography (ECC) is an approach to public-key cryptography based on the algebraic structure of elliptic curves over finite fields. The use of elliptic curves in cryptography was initially presented by Neal Koblitz and Victor S. Miller. Elliptic curve cryptosystem has advantages in terms of smaller key size and lower computational overhead in comparison with public key cryptosystem [2]. Many researchers have been presented the secure blind signature scheme with their own goals and limitations. Two properties a blind signature scheme should hold digital signature and blind signature. By using concept of Elliptic Curve Cryptosystem and blinding algorithm, the signer generates the blind signature without reading content of the message [5]. The scheme avoids the collision between different digital signatures generated by the same singer. The blind signature is a secure technique can be applied in ebusiness and other applications. Blind signature schemes are widely used for various applications of E-commerce like digital payment systems and electronic voting system etc where to maintain the privacy of consumer is necessary [9].

2013

This paper presents the simulation of privacy-related applications employing blind signature (BS) schemes. Two popular privacy-related applications: ‘traditional BS based electronic voting system (EVS) ’ and ‘traditional offline electronic payment protocol (EPP) ’ have been chosen here. A BS scheme is a cryptographic protocol that plays a vital role to conduct the electronic transactions of privacy-related applications securely but anonymously. It ensures the confidentiality of the private information of a user while she involves in an electronic transaction over the internet. Intuitively, existing BS schemes can be categorized as traceable and untraceable. RSA cryptosystem based two popular schemes from two categories: the scheme of Chaum [1] from traceable schemes and the scheme of Hwang et al. [2] from untraceable schemes have been chosen here for simulation. The upshot of the simulation model is the comparison of computation time requirement of blinding, singing, unblinding and ...

Lecture Notes in Computer Science, 1995

A blind signature scheme is a protocol for obtaining a signature from a signer such that the signer's view of the protocol cannot be linked to the resulting message-signature pair. Blind signature schemes are used in anonymous digital payment systems. Since the existing proposals of blind signature schemes provide perfect unlinkability, such payment systems could be misused by criminals, e.g. to safely obtain a ransom or to launder money. In this paper, a new type of blind signature schemes called fair blind signature schemes is proposed. Such schemes have the additional property that a trusted entity can deliver information allowing the signer to link his view of the protocol and the message-signature pair. T w o types of fair blind signature schemes are distinguished and several realizations are presented.

2008

Many e-voting schemes have been proposed in the literature. However, none of them is both secure and practical. In this paper, a practical and secure electronic voting protocol for large-scale voting over the Internet is investigated. Blind signature is applied to a voter's ballot making it impossible for anyone to trace the ballot back to the voter. Unlike previous blind signature based schemes, in which the authority directly signs its blind signature on voters' ballots, the authority in the proposed scheme signs blind signature on the voter marks that are generated by voters from ballot serial numbers. Moreover, threshold cryptosystem has been used to guarantee the fairness of the voting process. Using blind signature, this scheme can support all types of election easily and flexibly. Since we haven't use complex cryptographic techniques the proposed scheme is suitable for large scale elections.

Journal of Computer Security, 2013

Blind signatures allow users to obtain signatures on messages hidden from the signer; moreover, the signer cannot link the resulting message/signature pair to the signing session. This paper presents blind signature schemes, in which the number of interactions between the user and the signer is minimal and whose blind signatures are short. Our schemes are defined over bilinear groups and are proved secure in the common-reference-string model without random oracles and under standard assumptions: CDH and the decision-linear assumption. (We also give variants over asymmetric groups based on similar assumptions.) The blind signatures are Waters signatures, which consist of 2 group elements. Moreover, we instantiate partially blind signatures, where the message consists of a part hidden from the signer and a commonly known public part, and schemes achieving perfect blindness. We propose new variants of blind signatures, such as signer-friendly partially blind signatures, where the public part can be chosen by the signer without prior agreement, 3-party blind signatures, as well as blind signatures on multiple aggregated messages provided by independent sources. We also extend Waters signatures to non-binary alphabets by proving a new result on the underlying hash function.

2011

The blind signature technique Considered since its inception in 1982, as a key principle in building the e-cash schemes until 1996, when emerged the concept of partially blind signature, which played an important role in building electronic cash systems: It allows the signer to include pre-agreed information such as expiration date or collateral conditions in the resulting signature. In this thesis, we proposed a "non-repudiation and anonymous e-cash scheme based on partially blind signature". The main motivation of electronic cash research is providing anonymity. In fact, the unconditional anonymity may be misused for untraceable blackmailing of customers, which is called perfect crime. Furthermore, unconditional anonymity makes ease money laundering, illegal purchase, and bank robbery. Our proposed scheme enables the judge to specify a dishonest customer, bank, or blind office. In addition to that, our scheme is considered as a multi-purpose scheme because it satisfies t...

International Journal of Innovation, Management and Technology, 2014