REDOC - Wikipedia

In cryptography, REDOC II and REDOC III are block ciphers designed by Michael Wood (cryptographer) for Cryptech Inc and are optimised for use in software. Both REDOC ciphers are patented.^[1]

REDOC II (Cusick and Wood, 1990) operates on 80-bit blocks with a 160-bit key. The cipher has 10 rounds, and uses key-dependent S-boxes and masks used to select the tables for use in different rounds of the cipher. Cusick found an attack on one round, and Biham and Shamir (1991) used differential cryptanalysis to attack one round with 2300 encryptions. Biham and Shamir also found a way of recovering three masks for up to four rounds faster than exhaustive search. A prize of US$5,000 was offered for the best attack on one round of REDOC-II, and $20,000 for the best practical known-plaintext attack.

REDOC III is a more efficient cipher. It operates on an 80-bit block and accepts a variable-length key of up to 20,480 bits. The algorithm consists only of XORing key bytes with message bytes, and uses no permutations or substitutions. Ken Shirriff describes a differential attack on REDOC-III requiring 2²⁰ chosen plaintexts and 2³⁰ memory.

References

^ Bruce Schneier Applied cryptography: protocols, algorithms, and source code in C 1996 "REDOC III REDOC HI is a streamlined version of REDOC n, also designed by Michael Wood [1615]. It operates on an 80-bit block. The key length is variable and can be as large as 2560 bytes (20,480 bits). "

Thomas W. Cusick and Michael C. Wood: The REDOC II Cryptosystem, CRYPTO 1990, pp545–563.
Eli Biham and Adi Shamir, Differential Cryptanalysis of Snefru, Khafre, REDOC-II, LOKI and Lucifer. Advances in Cryptology—CRYPTO '91, Springer-Verlag, pp156–171 (gzipped PostScript).
Ken Shirriff, Differential Cryptanalysis of REDOC-III, (PS)

v t e Block ciphers (security summary)
Common algorithms	AES Blowfish DES (internal mechanics, Triple DES) Serpent SM4 Twofish
Less common algorithms	ARIA Camellia CAST-128 GOST IDEA LEA RC5 RC6 SEED Skipjack TEA XTEA
Other algorithms	3-Way Adiantum Akelarre Anubis Ascon BaseKing BassOmatic BATON BEAR and LION CAST-256 Chiasmus CIKS-1 CIPHERUNICORN-A CIPHERUNICORN-E CLEFIA CMEA Cobra COCONUT98 Crab Cryptomeria/C2 CRYPTON CS-Cipher DEAL DES-X DFC E2 FEAL FEA-M FROG G-DES Grand Cru Hasty Pudding cipher Hierocrypt ICE IDEA NXT Intel Cascade Cipher Iraqi Kalyna KASUMI KeeLoq KHAZAD Khufu and Khafre KN-Cipher Kuznyechik Ladder-DES LOKI (97, 89/91) Lucifer M6 M8 MacGuffin Madryga MAGENTA MARS Mercy MESH MISTY1 MMB MULTI2 MultiSwap New Data Seal NewDES Nimbus NOEKEON NUSH PRESENT Prince Q RC2 REDOC Red Pike S-1 SAFER SAVILLE SC2000 SHACAL SHARK Simon Speck Spectr-H64 Square SXAL/MBAL Threefish Treyfer UES xmx XXTEA Zodiac
Design	Feistel network Key schedule Lai–Massey scheme Product cipher S-box P-box SPN Confusion and diffusion Round Avalanche effect Block size Key size Key whitening (Whitening transformation)
Attack (cryptanalysis)	Brute-force (EFF DES cracker) MITM Biclique attack 3-subset MITM attack Linear (Piling-up lemma) Differential Impossible Truncated Higher-order Differential-linear Distinguishing (Known-key) Integral/Square Boomerang Mod n Related-key Slide Rotational Side-channel Timing Power-monitoring Electromagnetic Acoustic Differential-fault XSL Interpolation Partitioning Rubber-hose Black-bag Davies Rebound Weak key Tau Chi-square Time/memory/data tradeoff
Standardization	AES process CRYPTREC NESSIE NSA Suite B CNSA
Utilization	Initialization vector Mode of operation Padding

v t e Cryptography
General	History of cryptography Outline of cryptography Classical cipher Cryptographic protocol Authentication protocol Cryptographic primitive Cryptanalysis Cryptocurrency Cryptosystem Cryptographic nonce Cryptovirology Hash function Cryptographic hash function Key derivation function Secure Hash Algorithms Digital signature Kleptography Key (cryptography) Key exchange Key generator Key schedule Key stretching Keygen Machines 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
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