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RC2

RC2 variable-key-size block cipher with 64-bit blocks. Uses mixing and mashing operations over 18 rounds. Developed by Ron Rivest at RSA Data Security in 1987. Cryptographically broken.

Properties

Property	Value
Category	Block Ciphers
Sub-category	Block Cipher
Security status	❌ Broken
Complexity	Intermediate
Inventor	Ron Rivest
Year	1987
Origin	🇺🇸 United States
Source	algorithms/block/rc.js

Parameters

Parameter	Supported values
Key sizes	1 byte (8 bits) to 128 bytes (1024 bits)
Block sizes	8 bytes (64 bits)

Security

Status: ❌ Broken

Known vulnerabilities

Issue	Description	Mitigation
Related-key attacks	RC2 is vulnerable to related-key attacks due to weak key schedule	Use AES or other modern ciphers instead
Linear cryptanalysis	RC2 has linear approximations that reduce effective security	Algorithm is obsolete for secure applications

Documentation

• RFC 2268 - RC2 Algorithm Description
• RSA Data Security RC2 Specification

References

• Bouncy Castle RC2 Implementation
• NIST Computer Security Resource Center
• Applied Cryptography by Bruce Schneier

Test vectors

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

Vector 1 — RFC 2268 Test Vector #1: 8-byte all-zero key, 63-bit effective

Field	Value
key	0000000000000000
effectiveBits	63
input	0000000000000000
expected	ebb773f993278eff

Vector 2 — RFC 2268 Test Vector #2: 8-byte all-ones key, 64-bit effective

Field	Value
key	ffffffffffffffff
effectiveBits	64
input	ffffffffffffffff
expected	278b27e42e2f0d49

Vector 3 — RFC 2268 Test Vector #3: pattern key and plaintext, 64-bit effective

Field	Value
key	3000000000000000
effectiveBits	64
input	1000000000000001
expected	30649edf9be7d2c2

Vector 4 — RFC 2268 Test Vector #4: 1-byte key, 64-bit effective

Field	Value
key	88
effectiveBits	64
input	0000000000000000
expected	61a8a244adacccf0

Vector 5 — RFC 2268 Test Vector #5: 7-byte key, 64-bit effective

Field	Value
key	88bca90e90875a
effectiveBits	64
input	0000000000000000
expected	6ccf4308974c267f

Vector 6 — RFC 2268 Test Vector #6: 16-byte key, 64-bit effective

Field	Value
key	88bca90e90875a7f0f79c384627bafb2
effectiveBits	64
input	0000000000000000
expected	1a807d272bbe5db1

Vector 7 — RFC 2268 Test Vector #7: 16-byte key, 128-bit effective

Field	Value
key	88bca90e90875a7f0f79c384627bafb2
effectiveBits	128
input	0000000000000000
expected	2269552ab0f85ca6

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