We introduce delegatable functional signatures (DFS) which support the delegation of signingcapabilities to another party, called the evaluator, with respect to a functionality F . In a DFS,the signer of a message can choose an evaluator, specify how the evaluator can modify thesignature without voiding its validity, allow additional input and decide how the evaluator canfurther...

Digital signatures have become a key component of many embedded system solutions and are facing strong security and efficiency requirements. At the same time side-channel resistance is essential for a signature scheme to be accepted in real-world applications. Based on the Merkle signature scheme and Winternitz one-time signatures we propose a signature scheme with bounded side-channel leakage ...

In 2004, Abe et al. proposed a threshold signer-ambiguous signature scheme from variety of keys. Their scheme is a generalized case of the ring signature scheme, and it allows the key types to be based on the trapdoor one-way permutations (TOWP) or sigma-protocols including Schnorr’s signature scheme. However, the signed message is public for all, which may result in disputes. In this paper, we...

Rabi and Sherman [RS97] presented novel digital signature and unauthenticated secret-key agreement protocols, developed by themselves and by Rivest and Sherman. These protocols use \strong," total, commutative (in the case of multi-party secret-key agreement), associative one-way functions as their key building blocks. Though Rabi and Sherman did prove that associative one-way functions exist i...

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Blind digital signatures were introduced by Chaum. In this paper, we show how security and blindness properties for blind digital signatures, can be simultaneously defined and satisfied in the common reference string model, assuming an arbitrary one-way trapdoor permutation family. Thus, this paper presents the first complexity-based proof of security for blind signatures.

Signature file is one of the efficient access methods for retrieval of text database. In a large database server, parallel device is utilized to achieve concurrent access. Efficient allocation of signature file on parallel device minimizes the query response time and is important in the design of large databases. In this paper, we investigate the design of parallel signatutz file. We propose a ...

In this paper, we propose a forward secure ring signature scheme without random oracles. With forward security, if a secret key of a corresponding ring member is exposed, all previously signed signatures containing this member remain valid. Yet the one who has stolen the secret key cannot produce any valid signature belonged to the past time period. This is especially useful in the case of ring...