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" Certificateless public-key cryptosystem " is a new and attractive paradigm, which avoids the inherent key escrow property in identity-based public-key cryptosystems, and does not need expensive certificates as in the public key infrastructure. A strong security model for certificateless public key encryption was established by Al-Riyami and Paterson in(More)
Identity-based cryptosystems have an inherent key escrow issue, that is, the Key Generation Center (KGC) always knows user secret key. If the KGC is malicious, it can always impersonate the user. Certificateless cryptography, introduced by Al-Riyami and Paterson in 2003, is intended to solve this problem. However, in all the previously proposed(More)
We present a linkable spontaneously anonymous group (LSAG) signature scheme (alternatively known as linkable ring signature scheme) satisfying the following three properties. (1) Anonymity, or signer indis-tinguishability. (2) Linkability: That two signatures by the same signer can be linked. (3) Spontaneity: No group secret, therefore no group manager or(More)
Attribute-based encryption (ABE) is a promising tool for implementing fine-grained cryptographic access control. Very recently, motivated by reducing the trust assumption on the authority, and enhancing the privacy of users, a multiple-authority key-policy ABE system, together with a semi-generic anonymous key-issuing protocol, have been proposed by Chase(More)
— In 2003, Huang et al. proposed an authenticated key exchange protocol for secure communications between a sensor and a security manager in a self-organizing sensor network. The protocol is based on elliptic curve cryptography. In this letter, we show that a security manager will learn the long-term private key of a sensor after having one normal run of(More)
Attribute-based encryption (ABE) has been widely studied recently to support fine-grained access control of shared data. Anonymous ABE, which is a relevant notion to ABE, further hides the receivers' attribute information in ciphertexts because many attributes are sensitive and related to the identity of eligible users. However, in existing anonymous ABE(More)