Conditional Blind Signatures

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.

IACR ePrint, 2011

We revisit the definition of unforgeability of blind signatures as proposed by Pointcheval and Stern (Journal of Cryptology 2000). Surprisingly, we show that this established definition falls short in two ways of what one would intuitively expect from a secure blind signature scheme: It is not excluded that an adversary submits the same message m twice for signing, and then produces a signature for m = m. The reason is that the forger only succeeds if all messages are distinct. Moreover, it is not excluded that an adversary performs k signing queries and produces signatures on k + 1 messages as long as each of these signatures does not pass verification with probability 1.

Advances in Cryptology — CRYPTO 2000, 2000

Partially blind signature schemes are an extension of blind signature schemes that allow a signer to explicitly include necessary information (expiration date, collateral conditions, or whatever) in the resulting signatures under some agreement with the receiver. This paper formalizes such a notion and presents secure and efficient schemes based on a widely applicable method of obtaining witness indistinguishable protocols. We then give a formal proof of security in the random oracle model. Our approach also allows one to construct secure fully blind signature schemes based on a variety of signature schemes.

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].

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.

International Journal of Innovation, Management and Technology, 2014

2023

Blind digital signature schemes allow for digital documents to be signed and verified without revealing the contents of the document to the signer. This paper provides a brief introduction to blind digital signatures and surveys several of their uses in data privacy applications, including e-voting, anonymous e-cash, and e-healthcare. For concreteness, RSA-based signatures are considered in some detail.

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.

2012

Blind signature allows one user to get a signature without giving the signer any information about the actual message or the resulting signature. In this paper, we aim to improve the recently proposed Lin et al.’s Self-certified Partially Blind Signature Scheme[1] in order to withstand the security flaw in their scheme. The security of the improved scheme is enhanced in the blind signing phase of the scheme. The analysis shows that the proposed scheme resolves security problem in Lin et al.’s scheme and also meets the aspects of security features needed by a partial blind signature. KeywordsPartial blind signature; self-certified; bilinear pairing; security.