Abstract. This paper presents three methods for strengthening public key cryptosystems in such a way that they become secure against adaptively chosen ciphertext attacks. In an adaptively chosen ciphertext attack, an attacker can query the deciphering algorithm with any ciphertexts, except for the exact object ciphertext to be cryptanalyzed. The rst strengthening method is based on the use of one-way hash functions, the second on the use of universal hash functions and the third on the use of digital signature schemes. Each method is illustrated by an example o f a p u b l i c k ey cryptosystem based on the intractability o f computing discrete logarithms in nite elds. Two other issues, namely applications of the methods to public key cryptosystems based on other intractable problems and enhancement of information authentication capability t o the cryptosystems, are also discussed.
Zheng and Seberry REF presented three methods for immunizing public key cryptosystems against ACCA.
Practical Approaches to Attaining Security Against Adaptively Chosen Ciphertext Attacks
In Advances in Cryptology–Crypto ’92
Computer Science