Hawkynt

REDOC III

Michael Wood’s streamlined successor of REDOC II, built only from XORs: the key (1 to 34 bytes) seeds a 2560-byte key table that is folded into a 16-byte mask; two passes over the 8-byte block let each byte, masked, select a table row XORed into all other bytes. Follows Wood’s reference source code, which processes 64-bit blocks; Applied Cryptography describes an 80-bit block.

Properties

Property	Value
Category	Block Ciphers
Sub-category	Block Cipher
Security status	❌ Broken
Complexity	Intermediate
Inventor	Michael Wood
Year	1985
Origin	🇺🇸 United States
Source	algorithms/block/redoc.js

Parameters

Parameter	Supported values
Key sizes	1 byte (8 bits) to 34 bytes (272 bits)
Block sizes	8 bytes (64 bits)

Security

Status: ❌ Broken

Known vulnerabilities

Issue	Description	Mitigation
Differential cryptanalysis	Ken Shirriff’s differential attack recovers the key with about 2^20 chosen plaintexts and 2^30 memory.	Use AES or another vetted cipher.

Documentation

• Applied Cryptography source code (REDOC3.ZIP by Michael Wood)
• Wikipedia: REDOC
• US Patent 5,003,596 (Wood)

References

• REDOC III reference source (Michael Wood)

Test vectors

7 vectors ship with this algorithm and run in the test suite. Byte values are hexadecimal.

Vector 1 — REDOC III reference - sample key of the reference source, zero block

Field	Value
key	594280e7122b
input	0000000000000000
expected	d907f979f2477825

Vector 2 — REDOC III reference - 1-byte key (minimum)

Field	Value
key	80
input	0123456789abcdef
expected	c96886528fbdd43e

Vector 3 — REDOC III reference - 16-byte key

Field	Value
key	2b7e151628aed2a6abf7158809cf4f3c
input	6bc1bee22e409f96
expected	ab6a95c7fc7fd581

Vector 4 — REDOC III reference - zero 32-byte key, zero block

Field	Value
key	0000000000000000000000000000000000000000000000000000000000000000
input	0000000000000000
expected	4f83a9591536d9bd

Vector 5 — REDOC III reference - incrementing 32-byte key and block

Field	Value
key	000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f
input	0001020304050607
expected	731624c431837ac5

Vector 6 — REDOC III reference - all-ones 32-byte key and block

Field	Value
key	ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
input	ffffffffffffffff
expected	3485b3877f608773

Vector 7 — REDOC III reference - 34-byte key (maximum)

Field	Value
key	e0e1e2e3e4e5e6e7e8e9eaebecedeeef f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff 0001
input	fedcba9876543210
expected	8c81eb7f3db7776e

---

← All algorithms

This site is open source. Improve this page.