A new public key cryptosystem is proposed and analyzed. The scheme is quite practical, and is provably secure against adaptive chosen ciphertext attack under standard intractability assumptions. There appears to be no previous cryptosystem in the literature that enjoys both of these properties simultaneously.

A new public key encryption scheme, along with several variants, is proposed and analyzed. The scheme and its variants are quite practical, and are proved secure against adaptive chosen ciphertext attack under standard intractability assumptions. These appear to be the first public-key encryption schemes in the literature that are simultaneously practical and provably secure.

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This article motivates the importance of public-key cryptosystems that are secure against chosen ciphertext attack, and of rigorous security proofs. It also discusses the new cryptosystem developed by Cramer and Shoup, and its relevance in this regard.

The cryptographic community has developed many tools to incorporate distributed trust mechanisms into cryptographic primitives and protocols as well as primitives where parties are naturally distributed. Since the fastest growing paradigm in computing is distributed systems and communication networks, the importance of distributed mechanisms has been increasing, and will likely to be pervasive in the future. Here, we review the various distributed mechanisms that have been developed and applied to achieve distributed public key cryptosystem. We focus primarily on the more efficient threshold cryptographic schemes (based on sharing public-key functions) and exemplify (only) some of the issues regarding these systems.