Secure Cloud Email System On Privacy Protocol And Identity-Based Encryption

A flexible primitive alluded to as conditional identity-based broadcast PRE (CIBPRE) and formalizes its semantic security. CIBPRE enables a sender to encode a message to numerous collectors by indicating these beneficiaries' characters, and the sender can delegate a re-encryption key to an intermediary with the goal that he can change over the underlying ciphertext into another one to another arrangement of planned recipients. Also, the re-encryption key can be related with a condition to such an extent that lone the coordinating ciphertexts can be re-encoded, which enables the first sender to implement get to control over his remote ciphertexts in a fine-grained way. We propose a proficient CIBPRE conspire with provable security. In the instantiated plot, the underlying ciphertext, the re-encoded ciphertext and the re-encryption key are all in consistent size, and the parameters to create a re-encryption key are free of the first collectors of any underlying ciphertext

A CCA-Secure Identity-Based Conditional Proxy Re-Encryption without Random Oracles

Although a few unidirectional single-hop Identity-Based Proxy Re-Encryption (IBPRE) systems are available in the literature, none of them is CCA secure in the standard model. Besides, they can not support conditional re-encryption property, which allows a delegator to specify a condition for ciphertexts so that the proxy can re-encrypt ciphertexts only if the re-encryption key corresponding to the same condition is given. This paper, for the first time, proposes a new unidirectional single-hop Identity-Based Conditional Proxy Re-Encryption (IBCPRE) scheme that not only captures the property of IBPRE (i.e. identity-based re-encryption), but also supports conditional re-encryption. Moreover, the scheme can be proved secure against adaptive condition and adaptive identity chosen-ciphertext attacks in the standard model

A CCA-Secure Identity-Based Conditional Proxy Re-Encryption without Random Oracles

Although a few unidirectional single-hop Identity-Based Proxy Re-Encryption (IBPRE) systems are available in the literature, none of them is CCA secure in the standard model. Besides, they can not support conditional re-encryption property, which allows a delegator to specify a condition for ciphertexts so that the proxy can re-encrypt ciphertexts only if the re-encryption key corresponding to the same condition is given. This paper, for the first time, proposes a new unidirectional single-hop Identity-Based Conditional Proxy Re-Encryption (IBCPRE) scheme that not only captures the property of IBPRE (i.e. identity-based re-encryption), but also supports conditional re-encryption. Moreover, the scheme can be proved secure against adaptive condition and adaptive identity chosen-ciphertext attacks in the standard model

A Provably Secure Conditional Proxy Re-Encryption Scheme without Pairing

Blaze, Bleumer and Strauss introduced the notion of proxy re-encryption (PRE), which enables a semi-trusted proxy to transform ciphertexts under Alice\u27s public key into ciphertexts under Bob\u27s public key. The important property to note here is, the proxy should not learn anything about the plaintext encrypted. In 2009, Weng et al. introduced the concept of conditional proxy re-encryption (CPRE), which permits the proxy to re-encrypt only ciphertexts satisfying a condition specified by Alice into a ciphertext for Bob. CPRE enables fine-grained delegation of decryption rights useful in many practical scenarios, such as blockchain-enabled distributed cloud storage and encrypted email forwarding. Several CPRE schemes exist in the literature based on costly bilinear pairing operation in the random oracle model. We propose the first construction of an efficient CPRE scheme without pairing, satisfying chosen ciphertext security under the computational Diffie Hellman (CDH) assumption and its variant in the random oracle model