238 research outputs found
Secure Certificateless Public Key Encryption without Redundancy
Certificateless public key cryptography was introduced to solve the
key escrow problem in identity based cryptography while enjoying the
most attractive {\em certificateless} property. In this paper, we
present the first {\em secure} certificateless public key encryption
(CLPKE) scheme {\em without redundancy}. Our construction provides
optimal bandwidth and a quite efficient decryption process among all
the existing CLPKE schemes. It is provably secure against adaptive
chosen ciphertext attacks in the random oracle model under a
slightly stronger assumption
A revocable certificateless signature scheme
Certificateless public key cryptography (CLPKC), with properties of no key escrow and no certificate, has received a lot of attention since its invention. However, membership revocation in certificateless cryptosystem still remains a non-trivial problem: the existing solutions are not practical for use due to either a costly mediator or enormous computation (secret channel). In this paper, we present a new approach to revocation in CLPKC with a concrete construction of a revocable certificateless signature (RCLS) scheme. In our scheme, a user\u27s private key is composed of three parts: an initial partial private key, a time key and a secret value. The transmission of updated-key requires only a public channel, which makes our RCLS scheme more efficient than other methods. We first provide formal definition and security model for a RCLS scheme. The new scheme is proved secure in the random oracle model, based on the Computational Diffie-Hellman problem
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