The concept of proxy re-cryptography comes from the work of Blaze, Bleumer, and Strauss in 1998. The goal of proxy re-encryption is to securely enable the re-encryption of ciphertexts from one key to another, without relying on trusted parties. Identity based proxy re-encryption extends proxy re-encryption to the identity based setting. In this paper, we construct an identity based proxy re-encryption (IBPRE) scheme which can achieve master secret secure, while almost all of the previous efficient IBPRE schemes can not.Index Terms-Identity based proxy re-encryption, master secret secure.
Proxy re-encryption (PRE) allows a proxy to transform a ciphertext for Alice (delegator) to be the one which can be decrypted by Bob (delegatee). Since it is introduced by Blaze et al. in 1998, many variants of PRE have been proposed. In this paper,we concentrate on two of them: anonymous conditional proxy re-encryption (ACPRE) and constrained proxy re-encryption with keyword search (PRES). Conditional proxy re-encryption (CPRE) is a primitive which only allows those ciphertexts satisfying the condition can be re-encrypted correctly by the proxy. Anonymous conditional proxy reencryption (ACPRE) requires the proxy not knowing which condition the ciphertext associated with. PRES is a primitive which allows the proxy simultaneously re-encrypt and search the delegator's ciphertext. Based on the PRES proposed by Shao et al., We show the definition of constrained proxy reencryption with keyword search (CPRES), give its security models and discuss its potential applications. At last, based on a concrete ACPRE scheme , we construct a concrete CPRES scheme.
Efficient identity based signature/signcryption in the standard model with full security has been pursued for a long time. At ISDPE'07, Ren and Gu claimed to construct efficient identity based signature/signcryption schemes with full security in the standard model. They claimed their schemes have short public parameters, high efficiency and a tight reduction. But in this paper we give attacks to their schemes to show their schemes are not secure.Index Terms-Identity based signature/signcryption, standard model, attack.
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