EPOC: Efficient Probabilistic Public-Key Encryption (Submission to P1363a)
Tatsuaki Okamoto, Shigenori Uchiyama, Eiichiro Fujisaki · 1998
We describe a novel public-key cryptosystem, EPOC (E#cient Probabilistic Public-Key Encryption), which has two versions: EPOC-1 and EPOC-2. EPOC-1 is a public-key encryption system that uses a one-way trapdoor function and a random function (hash function). EPOC-2 is a public-key encryption system that uses a one-way trapdoor function, two random functions (hash functions) and a symmetric-key encryption (e.g., one-time padding and block-ciphers). EPOC has several outstanding properties as follows: 1. EPOC-1 is semantically secure or non-malleable against chosen ciphertext attacks (IND-CCA2 or NM-CCA2) in the random oracle model under the p-subgroup assumption, which is comparable to the quadratic residue and higher degree residue assumptions. 2. EPOC-2 with one-time padding is semantically secure or non-malleable against chosen ciphertext attacks (IND-CCA2 or NM-CCA2) in the random oracle model under the factoring assumption. 3. EPOC-2 with symmetric encryption is semantically secure o...