We study an adaptive variant of oblivious transfer in which a sender has N messages, of which a receiver can adaptively choose to receive k one-after-the-other, in such a way that (a) the sender learns nothing about the receiver’s selections, and (b) the receiver only learns about the k requested messages. We propose two practical protocols for this primitive that achieve a stronger security no...

In real life, one requires signatures to be from people who fulfill certain criteria, implying that they should possess specific attributes. For example, Alice might want a signature from an employee in Bobs company who is a member in the IT staff, a senior manager within the biometrics team or at least a junior manager in the cryptography team. In such a case an Attribute Based Group Signature...

Malleable signature schemes (MSS) enable a third party to alter signed data in a controlled way, maintaining a valid signature after an authorized change. Most well studied cryptographic constructions are (1) redactable signatures (RSS), and (2) sanitizable signatures (SSS). RSSs allow the removal of blocks from a signed document, while SSSs allow changing blocks to arbitrary strings. We rigoro...

Designated confirmer signatures, initially introduced by Chaum in 1994, eliminated the undeniable signature shortcoming in which the signature can only be verified through the cooperation of the original signer. This paper proposes several practical constructions to multiple designated confirmer signature schemes. We employ the messagedependent proof of equality of the discrete logarithm and tr...

Digital signature scheme is an important research topic in cryptography. An ordinary digital signature scheme allows a signer to create signatures of documents and the generated signatures can be verified by any person. A proxy signature scheme, a variation of ordinary digital signature scheme, enables a proxy signer to sign messages on behalf of the original signer. To be used in different app...

Abstract Blind signatures are a decades-old privacy enhancing technology. It is not always clearly understood that blind actually possess two separate properties: the intuitive understanding message to be signed hidden from signer, and fact resulting signature unlinkable (meaning signer cannot later tell in which session it created particular signature). The question is: how exactly should thes...

We present the first blind signature scheme that is efficient and provably secure without random oracles under concurrent attacks utilizing only two rounds of short communication. The scheme is based on elliptic curve groups for which a bilinear map exists and on extractable and equivocable commitments. The unforgeability of the employed signature scheme is guarranteed by the LRSW assumption wh...

In this study, the security of Novel Enhanced Quantum Representation (NEQR) of quantum images are suggested by using the Quantum Fourier Transform (QFT ) with blind trent. In the protocol, QFT and keys are used to share signature with recipients. So all members know only their signature information which are encrypted output of the QFT . This improves the security of the protocol. In addition, ...

* 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...

A blind nonlinear interference cancellation receiver for code-division multiple-access(CDMA-) based communication systems operating over Rayleigh flat-fading channels is proposed. The receiver which assumes knowledge of the signature waveforms of all the users is implemented in an asynchronous CDMA environment. Unlike the conventional MMSE receiver, the proposed blind ICA multiuser detector is ...