Key escrow

About: Key escrow is a research topic. Over the lifetime, 1162 publications have been published within this topic receiving 19616 citations.

Lattice-Based Revocable Certificateless Signature

Abstract: Certificateless signatures (CLS) are noticeable because they may resolve the key escrow problem in ID-based signatures and break away the management problem regarding certificate in conventional signatures. However, the security of the mostly previous CLS schemes relies on the difficulty of solving discrete logarithm or large integer factorization problems. These two problems would be solved by quantum computers in the future so that the signature schemes based on them will also become insecure. For post-quantum cryptography, lattice-based cryptography is significant due to its efficiency and security. However, no study on addressing the revocation problem in the existing lattice-based CLS schemes is presented. In this paper, we focus on the revocation issue and present the first revocable CLS (RCLS) scheme over lattices. Based on the short integer solution (SIS) assumption over lattices, the proposed lattice-based RCLS scheme is shown to be existential unforgeability against adaptive chosen message attacks. By performance analysis and comparisons, the proposed lattice-based RCLS scheme is better than the previously proposed lattice-based CLS scheme, in terms of private key size, signature length and the revocation mechanism.

Strong forward security

Abstract: Forward security has been propose as a method to minimized the consequences of key exposure In this paper we analyze this method and consider vulnerability, which is due to the fact that the exposure may not have been detected All forward secure crytosystems proposed so far are vulnerable during the period between key exposure and it detection We consider the notion of strong forward in which crytographically processed data is protected not only for the periods prior to key exposure but also after key exposure, and present two applications with this novel property: a basic public key crytosystem and an EIGamal-based key escrow scheme

Certificateless signature and blind signature

Abstract: Certificateless public key cryptography is a new paradigm introduced by Al-Riyami and Paterson. It eliminates the need of the certificates in traditional public key cryptosystems and the key escrow problem in IDentity-based Public Key Cryptography (ID-PKC). Due to the advantages of the certificateless public key cryptography, a new efficient certificateless pairing-based signature scheme is presented, which has some advantages over previous constructions in computational cost. Based on this new signature scheme, a certificateless blind signature scheme is proposed. The security of our schemes is proven based on the hardness of computational Diffie-Hellman problem.

On Tamper-Resistance from a Theoretical Viewpoint

Abstract: Tamper-proof devices are pretty powerful. They can be used to have better security in applications. In this work we observe that they can also be maliciously used in order to defeat some common privacy protection mechanisms. We propose the theoretical model of trusted agent to formalize the notion of programmable secure hardware. We show that protocols not using tamper-proof devices are not deniable if malicious verifiers can use trusted agents. In a strong key registration model, deniability can be restored, but only at the price of using key escrow. As an application, we show how to break invisibility in undeniable signatures, how to sell votes in voting schemes, how to break anonymity in group/ring signatures, and how to carry on the Mafia fraud in non-transferable protocols. We conclude by observing that the ability to put boundaries in computing devices prevents from providing full control on how private information spreads: the concept of sealing a device is in some sense incompatible with privacy.

Method and system for certificateless and pairing-free identity-based proxy signcryption

Abstract: The embodiment of the invention provides a method and a system for certificateless and pairing-free identity-based proxy signcryption. The method mainly comprises the following steps: a sender generates a private key and a public key thereof according to common parameters of the system and identity information parameters of the sender, generates proxy information based on the private key and the public key thereof, and sends the proxy information to a proxy; after the proxy information passes verification of the proxy, the proxy generates a proxy key, performs signcryption on a message needing to be sent based on the proxy key and the common parameters of the system to obtain a signcrypted message and an intermediate parameter, and sends the signcrypted message and the intermediate parameter to a receiver; and the receiver recovers the signcrypted message with the use of the intermediate parameter and the common parameters of the system to obtain a recovered message, and verifies the recovered message. The certificateless and pairing-free identity-based proxy signcryption scheme provided by the embodiment of the invention has both signature and encryption characteristics and has the feature of proxy. A key generation center only generates part of keys of a user, no certificate is needed, and the problem of key escrow is solved.