EPOC (Efficient Probabilistic Public Key Encryption) is a probabilistic public-key encryption scheme.

EPOC was developed in 1999 by T. Okamoto, S. Uchiyama and E. Fujisaki of NTT Labs in Japan. It is based on the random oracle model, in which a primitive public-key encryption function is converted to a secure encryption scheme by use of a truly random hash function; the resulting scheme is designed to be semantically secure against a chosen ciphertext attack.

EPOC's primitive encryption function is the OU (Okamoto–Uchiyama) function, in which to invert the OU function is proven to be as hard as factoring a composite integer public key. There are three versions of EPOC:

EPOC-1 uses a one-way trapdoor function and a random function (hash function);
EPOC-2 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-3 uses the Okamoto–Uchiyama one-way trapdoor function and two random functions (hash functions) as well as any symmetric encryption scheme such as the one-time pad, or any classical block cipher.

EPOC-1 is designed for key distribution; EPOC-2 and EPOC-3 are designed for both key distribution and encrypted data transfer.

References

T. Okamoto, S. Uchiyama and E. Fujisaki (1999). "EPOC: Efficient Probabilistic Public-Key Encryption Archived 2005-11-30 at the Wayback Machine", Contribution to IEEE – describes EPOC-1 and EPOC-2.
T. Okamoto and D. Pointcheval (2000). "EPOC-3: Efficient Probabilistic Public-Key Encryption (Version 2) Archived 2005-11-30 at the Wayback Machine", Contribution to IEEE – describes EPOC-3.
T. Okamoto; S. Uchiyama (1998). "A new public-key cryptosystem as secure as factoring". Advances in Cryptology — EUROCRYPT'98. Lecture Notes in Computer Science. Vol. 1403. pp. 308–318. doi:10.1007/BFb0054135. ISBN 978-3-540-64518-4.((cite book)): CS1 maint: multiple names: authors list (link)

Public-key cryptography

Algorithms

Integer factorization	Benaloh Blum–Goldwasser Cayley–Purser Damgård–Jurik GMR Goldwasser–Micali Naccache–Stern Paillier Rabin RSA Okamoto–Uchiyama Schmidt–Samoa
Discrete logarithm	BLS Cramer–Shoup DH DSA ECDH X25519 X448 ECDSA EdDSA Ed25519 Ed448 ECMQV EKE ElGamal signature scheme MQV Schnorr SPEKE SRP STS
Lattice/SVP/CVP/LWE/SIS	BLISS Kyber NewHope NTRUEncrypt NTRUSign RLWE-KEX RLWE-SIG
Others	AE CEILIDH EPOC HFE IES Lamport McEliece Merkle–Hellman Naccache–Stern knapsack cryptosystem Three-pass protocol XTR

Theory

Standardization

Topics

v t e Cryptography
General	History of cryptography Outline of cryptography Cryptographic protocol Authentication protocol Cryptographic primitive Cryptanalysis Cryptocurrency Cryptosystem Cryptographic nonce Cryptovirology Hash function Cryptographic hash function Key derivation function Digital signature Kleptography Key (cryptography) Key exchange Key generator Key schedule Key stretching Keygen Cryptojacking malware Ransomware Random number generation Cryptographically secure pseudorandom number generator (CSPRNG) Pseudorandom noise (PRN) Secure channel Insecure channel Subliminal channel Encryption Decryption End-to-end encryption Harvest now, decrypt later Information-theoretic security Plaintext Codetext Ciphertext Shared secret Trapdoor function Trusted timestamping Key-based routing Onion routing Garlic routing Kademlia Mix network
Mathematics	Cryptographic hash function Block cipher Stream cipher Symmetric-key algorithm Authenticated encryption Public-key cryptography Quantum key distribution Quantum cryptography Post-quantum cryptography Message authentication code Random numbers Steganography
Category

See also

References