Public-key cryptosystems provably secure against chosen ciphertext attacks
STOC '90 Proceedings of the twenty-second annual ACM symposium on Theory of computing
Non-Interactive Zero-Knowledge Proof of Knowledge and Chosen Ciphertext Attack
CRYPTO '91 Proceedings of the 11th Annual International Cryptology Conference on Advances in Cryptology
On the Existence of 3-Round Zero-Knowledge Protocols
CRYPTO '98 Proceedings of the 18th Annual International Cryptology Conference on Advances in Cryptology
A Practical Public Key Cryptosystem Provably Secure Against Adaptive Chosen Ciphertext Attack
CRYPTO '98 Proceedings of the 18th Annual International Cryptology Conference on Advances in Cryptology
On the Security of ElGamal Based Encryption
PKC '98 Proceedings of the First International Workshop on Practice and Theory in Public Key Cryptography: Public Key Cryptography
Towards Practical Public Key Systems Secure Against Chosen Ciphertext Attacks
CRYPTO '91 Proceedings of the 11th Annual International Cryptology Conference on Advances in Cryptology
Modern Cryptography: Theory and Practice
Modern Cryptography: Theory and Practice
The random oracle methodology, revisited
Journal of the ACM (JACM)
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This paper proposes a new public-key encryption scheme which removes one element from the public-key tuple of the original Cramer-Shoup scheme. As a result, a ciphertext is not a quadruple but a triple at the cost of a strong assumption, the third version of knowledge of exponent assumption (KEA3). Under assumptions of KEA3, a decision Diffie-Hellman (DDH) and a variant of target collision resistance (TCRv), the new scheme is proved secure against indistinguishable adaptive chosen ciphertext attack (IND-CCA2). This scheme is as efficient as Damgård ElGamal (DEG) scheme when it makes use of a well-known algorithm for product of exponentiations. The DEG scheme is recently proved IND-CCA1 secure by Bellare and Palacio in ASIACRYPT 2004 under another strong assumption. In addition to our IND-CCA2 secured scheme, we also believe that the security proof procedure itself provides a well insight for ElGamal-based encryption schemes which are secure in real world.