Security Analysis on a Blind Signature Scheme Based on Elgamal Signature Equation

Liao et al. proposed first blind signature schemes without random oracles from pairings and provided security proofs in CIS'05. However, we show that their blind scheme is neither blind, nor unforgeable, anyone not to query the signing oracle can forge signature of any message.

A blind signature enables a user to obtain signatures on any message from an authority who cannot acquire any information on the message being signed. A blind ring signature scheme is designed as a ring signature scheme with the blindness property. The scheme allows any member of a group anonymously sign a message on behalf of the group. Also, the user with the message can blind it before transmitting to the group. At Asiacrypt 2010, Rückert constructed the first blind signature scheme using ideal lattices. Recently, Zhang, Jiang and Zheng, and Alkadri, Bansarkhani and Buchmann proposed two improved blind signature schemes based on the SIS problem and the Ring SIS problem in 2018 and 2020, respectively. At WISA 2019, motivated by these blind signature schemes, Le, Duong and Susilo constructed the first lattice-based blind ring signature scheme provably secure under the hardness assumption of the SIS problem in random oracle model. In this paper, we show that Rückert’s scheme, Alkadri-Bansarkhani-Buchmann scheme and Zhang-Jiang-Zheng scheme, and Le-Duong-Susilo scheme do not achieve blindness, i.e. the signer can link a valid message-signature pair after interacting with various users. We show that the cause of vulnerabilities of the blind schemes is that the blinding factors to hide real messages being signed are exposed by specific algebraic relations in the underlying rings. To hide the blinding factors, we use homomorphic encryption schemes. Finally, we propose a generic construction from a semantically secure homomorphic encryption scheme and a one-more unforgeable blind signature scheme that does not achieve blindness to a new blind signature scheme that achieves blindness as well as one-more unforgeability.

An efficient provably secure identity-based blind signature (IBBS) scheme based on bilinear pairings is proposed. Assuming the intractability of the q-Strong Diffie-Hellman problem, our IBBS is unforgeable under adaptive chosen-message and ID attack. Because of avoiding using the inefficient MapToPoint function, our IBBS can offer advantages in runtime over the schemes available. Based on this ID-based blind signature scheme, we describe the first ID-based threshold blind signature (TBS) and show that it has security properties of unforgeability and robustness.

An efficient provably secure identity-based blind signature (IBBS) scheme based on bilinear pairings is proposed. Assuming the intractability of the q-Strong Diffie-Hellman problem, our IBBS is unforgeable under adaptive chosen-message and ID attack. Because of avoiding using the inefficient MapToPoint function, our IBBS can offer advantages in runtime over the schemes available. Based on this ID-based blind signature scheme, we describe the first ID-based threshold blind signature (TBS) and show that it has security properties of unforgeability and robustness.

In order to solve the problem of computational complexity brought by bilinear pairing in identity based blind signature, a new ID-based blind signature scheme is proposed combined with Elgamal algorithm, and the blind signature scheme is applied to the field of civil aviation data transmission firstly. The signer is not visible to the original message and can't restore the original message by the signed message. The use of hash function to deal with both private key and the identity information is secure under the Random Oracle Model. Based on the classical Elgamal algorithm, the problem belongs to the discrete logarithm problem. The scheme is applied to the field of civil aviation data transmission and the experimental results show that it can effectively resist key recovery attacks and signature forgery attacks. The scheme has strong anti-attack ability and effective operation ability. Compared with other schemes, it needs less module operation and exponential operation. To sum up, this scheme is better than other schemes in the civil aviation's field.

A blind ring signature scheme is a combination of a ring signature and a blind signature, which allows not only any member of a group of signers to sign on a message on behalf of the group without revealing its identity but also the user who possesses the message to blind it before sending to the group to be signed. Blind ring signature schemes are essential components in e-commercial, e-voting etc. In this paper, we propose the first blind ring signature scheme based on lattices. More precisely, our proposed scheme is proven to be secure in random oracle model under the hardness of the short integer solution (SIS) problem.

We analyze several alternatives of blind digital signatures, for an electronic electoral system in a distributed architecture environment, in view of the persistence of blind signature problems in electoral processes. The objective is to recognize and propose an alternative of a blind signature scheme to improve privacy, confidentiality for the voter and in this way reduce any type of vulnerability with respect to the information of the same. The deductive method is used to summarize the information of the scientific articles studied. It results in a blind signature prototype based on algorithms to mitigate the vulnerabilities of voter information. It is concluded that, in order to guarantee privacy and confidentiality, several blind signature schemes must be implemented together to obtain the benefits of each of them, thus reducing the risks to which the voter's information is exposed in this process.

Blind signature allows a user to obtain a signature from an authority on any document, in such a way that the authority learns nothing about the message that is being signed. The blindness is an important property which distinguishes the blind signature from other signature schemes. Partially blind signature is an extension of blind signature that allows a signer to sign a partially blinded message that include pre-agreed information in the resulting signatures. Recently, Liao et al. proposed a pairing-based provable blind signature scheme without random oracles, and Hu et al. proposed an efficient ID-based partially blind signature scheme with security proof. But in this paper, we show that the two schemes do not satisfy the blindness and partially blindness, respectively. Liao et al.'s scheme is linkability and in Hu et al.'s scheme, a malicious user can replace pre-agreed common information with a special information

Blind signature is an interesting cryptographic primitive which allows user to get signature on his document from signatory authority, without leaking any information. Blind signature is useful in many e-commerce applications where user’s anonymity is the main concern. Since the Zhang et al., was the first to propose the identity based blind signature, many schemes based on bilinear pairing have been proposed. But the computational cost of pairing operation on elliptic curve is around 20 times the point multiplication on an elliptic curve. In order to save the running time, we present a new Identity-Based Blind Signature (ID-BS) scheme whose security is based on elliptic curve discrete logarithm problem (ECDLP). Performance comparison shows that proposed scheme reduces the cost of computation. Security analysis shows that proposed scheme is secure against the adversary and achieves the property of blindness and Non-forgeabillity. At the end; we propose an e-cash payment system based on our ID-based blind signature scheme.

Proxy blind signature which combines the properties of both proxy signature and blind signature. In a proxy blind signature scheme, the proxy signer is allowed to generate a blind signature on behalf of the original signer. The proxy blind signature scheme is useful in several applications such as e-voting, e-payment and mobile agent environments. In this paper, we present an efficient proxy blind signature scheme based on discrete logarithm problem, which satisfies the secure properties of both the blind signature scheme and the proxy signature scheme with low computation. Analysis shows that our scheme is secure and efficient.

In this paper, we consider a scenario where a bitcoin liquidity provider sells bitcoins to clients. When a client pays for a bitcoin online, the provider is able to link the client's payment information to the bitcoin sold to that client. To address the privacy concerns of clients, we require that the bitcoin provider cannot tell the relationship between the real identities of clients and the sold bitcoins in the blockchain. This requirement can be effectively achieved by using blind signatures. However, existing blind signature schemes are incompatible with the Elliptic Curve Digital Signature Algorithm (ECDSA) which is used by most of the existing bitcoin protocol, thus cannot be applied directly in Bitcoin. In this paper, we propose a new blind signature scheme that allows generating a blind signature compatible with the standard ECDSA. Afterwards, we make use of the new scheme to achieve bitcoin transaction anonymity. The new scheme is built on a variant of the Paillier cryptosystem and its homomorphic properties. As long as the modified Paillier cryptosystem is semantically secure, the new blind signature scheme has blindness and unforgeability.

Most of the proxy blind schemes are based on the identity or on certificate. In this paper, a new certificateless proxy blind signature scheme is presented. This scheme firstly avoids the inherent escrow of identity-based cryptography and then doesn’t require certificates to guarantee the authenticity of public keys. This scheme fulfills the properties of both the proxy signature and the blind signature.

Blind signatures play an important role in both electronic cash and electronic voting systems. Blind signatures should be secure against various attacks (such as signature forgeries). The work puts a special attention to secret key exposure attacks, which totally break digital signatures. Signatures that resist secret key exposure attacks are called forward secure in the sense that disclosure of a current secret key does not compromise past secret keys. This means that forward-secure signatures must include a mechanism for secret-key evolution over time periods. This paper gives a construction of the first blind signature that is forward secure. The construction is based on the SIS assumption in the lattice setting. The core techniques applied are the binary tree data structure for the time periods and the trapdoor delegation for the key-evolution mechanism.

Blind signatures, introduced by Chaum, allow a user to obtain a signature on a message without revealing any thing about the message to the signer. Blind signatures play an important role in plenty of applications such as e-voting, e-cash system where anonymity is of great concern. Identity based(ID-based) public key cryptography can be a good alternative for certificate based public key setting, especially when efficient key management and moderate security are required. In this paper, we propose an ID-based blind signature scheme from bilinear pairings. The proposed scheme is based on the Hess ID- based digital signature scheme. Also we analyze security and efficiency of the proposed scheme.

Blind signatures are one of the key techniques of Privacy-Enhancing Technologies (PETs). They appear as a component of many schemes, including, in particular, the Privacy Pass technology. Blind-signature schemes provide provable privacy: the signer cannot derive any information about a message signed at user’s request. Unfortunately, in practice, this might be just an illusion. We consider a novel but realistic threat model where the user does not participate in the protocol directly but instead uses a provided black-box device. We then show that the black-box device may be implemented in such a way that, despite a provably secure unblinding procedure, a malicious signer can link the signing protocol transcript with a resulting unblinded signature. Additionally, we show how to transmit any short covert message between the black-box device and the signer. We prove the stealthiness of these attacks in anamorphic cryptography model, where the attack cannot be detected even if all private keys are given to an auditor. At the same time, an auditor will not detect any irregular behavior even if the secret keys of the signer and the device are revealed for audit purposes (anamorphic cryptography model). We analyze the following schemes: (1) Schnorr blind signatures, (2) Tessaro–Zhu blind signatures, and their extensions. We provide a watchdog countermeasure and conclude that similar solutions are necessary in practical implementations to defer most of the threats.