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 doe...

We improve on the Bresson–Stern–Szydlo threshold ring signature scheme which uses Shamir secret sharing scheme [6] by showing that the security can be proved under a strictly weaker assumption, that is the random oracle model rather than the ideal cipher model. Then we propose an efficient (n− t)-out-of-n threshold ring signature scheme which is efficient when t is small compared with n. Our sc...

In this paper, we construct an anonymous and decentralized cryptocash system which is potentially secure against quantum computers. In order to achieve that, a linkable ring signature based on ideal lattices is proposed. The size of a signature in our scheme is O(logN), where N is the cardinality of the ring. The framework of our cryptocash system follows that of CryptoNote with some modificati...

Since the introduction of Identity-based (ID-based) cryptography by Shamir in 1984, numerous ID-based signature schemes have been proposed. In 2001, Rivest et al. introduced ring signature that provides irrevocable signer anonymity and spontaneous group formation. In recent years, ID-based ring signature schemes have been proposed and almost all of them are based on bilinear pairings. In this p...

Ring signature enables an user to anonymously sign a message on behalf of a group of users termed as ‘ring’ formed in an ‘ad-hoc’ manner. A naive scheme produces a signature linear in the size of the ring, but this is extremely inefficient when ring size is large. Dodis et al. proposed a constant size scheme in EUROCRYPT’13, but provably secure in random oracle model. Best known result without ...

Since the introduction of Identity-based (ID-based) cryptography by Shamir in 1984, numerous ID-based signature schemes have been proposed. In 2001, Rivest et al. introduced ring signature that provides irrevocable signer anonymity and spontaneous group formation. In recent years, ID-based ring signature schemes have been proposed and all of them are based on bilinear pairings. In this paper, w...

A ring signature scheme can be viewed as a group signature scheme with no anonymity revocation and with simple group setup. A linkable ring signature (LRS) scheme additionally allows anyone to determine if two ring signatures have been signed by the same group member. Recently, Dodis et al. [19] gave a short (constant-sized) ring signature scheme. We extend it to the first short LRS scheme, and...

The only known construction of ID-based ring signature schemes which maybe secure in the standard model is to attach certificates to non-ID-based ring signatures. This method leads to schemes that are somewhat inefficient and it is an open problem to find more efficient and direct constructions. In this paper, we propose two such constructions. Our first scheme, with signature size linear in th...

A (t, n) threshold signature scheme allows t or more group members to generate signatures on behalf of a group with n members, while any t−1 or less members cannot do the same thing. In 2001, based on a variant of ElGamal digital signature scheme, Li et al. proposed two (t, n) threshold signature schemes with traceable signers. One of their schemes needs the assistance of a mutually trusted cen...

Ring signatures, introduced by Rivest, Shamir and Tauman, enable a user to sign a message anonymously on behalf of a “ring”. A ring is a group of users, which includes the signer. We propose a ring signature scheme that has size O( √ N) where N is the number of users in the ring. An additional feature of our scheme is that it has perfect anonymity. Our ring signature like most other schemes use...