This chapter describes a privacy-secure digital watermarking scheme for fair content trading against cybercrime on digital content piracy and privacy leakage. Conventional digital watermarking schemes are effective only for providers since privacy of a client is not concerned though content is protected. Provider’s security as well as client’s security need to be considered to enhance security ...

The concept of proxy signature was introduced by Mambo et al. to delegate signing capability in the digital world. In this paper, we show that three existing proxy signature schemes without certificates, namely, the Qian and Cao identity-based proxy signature (IBPS) scheme, the Guo et al. IBPS scheme and the Li et al. certificateless proxy signature (CLPS) scheme are insecure against universal ...

Blind signature is the concept to ensure anonymity of e-coins. Untracebility and unlinkability are two main properties of real coins, which require mimicking electronically. Whenever a user is permitted to spend an e-coin, he is in need to ful ll above requirements of blind signature. In this paper a proxy blind signature scheme is given with which a proxy is able to make proxy blind signature ...

The security of ordinary digital signature schemes relies on a computational assumption. Fail-stop signature (FSS) schemes provide security for a signer against a forger with unlimited computational power by enabling the signer to provide a proof of forgery, if it occurs. Signing long messages using FSS requires a hash function with provable security which results in slow signature generation. ...

This study investigates all variations of the He’s digital signature scheme based on factoring and discrete logarithms. In contrast to three modular exponentiation computation, the optimal two schemes of generalized He’s signature verification reveals that only two modular exponentiation is needed for signature verification. Key-Words: Digital signature, Batch verify, Computation complexity.

* This research is partially supported by the National Science Council, Taiwan, R.O.C., under grant NSC92-2213-E-110-035. Abstract Hwang, Lee, and Lai introduced a new blind signature scheme based on RSA cryptosystem. In this paper, their scheme is demonstrated as being insecure and an improved scheme against the attack is proposed. In addition, Hwang, Lee, and Lai’s comments on Fan’s blind sig...

In this paper, a proxy blind signature scheme based on bilinear pairing is proposed. The proposed proxy blind signature is existential unforgeable under adaptively chosen warrant attacks and chosen message attacks upon the CDH assumptions and DBDH assumptions in the Random Oracle Model. In order to make all levels of banks issue electronic coin, the proxy blind signature scheme is applied to co...

Mixcoin is a Bitcoin mixing protocol proposed by Bonneau et al. which provides strong accountability guarantees [13]. However, in the Mixcoin protocol, the mapping from a user’s input to output address is visible to the mixing server. We modify the Mixcoin protocol to provide guarantees that the input/output address mapping for any user is kept hidden from the mixing server. In order to achieve...

The blind signature schemes are useful in some applications where the anonymity is a big issue. Examples include the online voting systems and the electronic cash systems. Since the first identity-based blind signature scheme was proposed by Zhang et al., many identity-based blind signature schemes using bilinear pairings have been proposed. But the relative computation cost of the pairing is a...

This manuscript presents a fast blind signature scheme with extremely low computation for users. Only several modular additions and multiplications are required for a user to obtain and verify a signature in the proposed scheme. Comparing with the existing ones in the literature, the scheme greatly reduces the computations for users. Keywords—Blind signatures, Untraceable electronic cash, Secur...