Variable-key-size stream cipher using 256-byte internal state with KSA and PRGA algorithms. BROKEN - deprecated by RFC 7465 due to statistical biases and related-key attacks.
| Property | Value |
|---|---|
| Category | Stream Ciphers |
| Sub-category | Stream Cipher |
| Security status | ❌ Broken |
| Complexity | Beginner |
| Inventor | Ron Rivest |
| Year | 1987 |
| Origin | 🇺🇸 United States |
| Source | algorithms/stream/rc4.js |
| Parameter | Supported values |
|---|---|
| Key sizes | 1 byte (8 bits) to 256 bytes (2048 bits) |
| Nonce sizes | 0 bytes (0 bits) |
Status: ❌ Broken
| Issue | Description | Mitigation |
|---|---|---|
| Statistical Biases | RC4 keystream contains detectable statistical biases exploitable in various attack scenarios | DO NOT USE - Use ChaCha20 or AES-GCM instead |
| Related-Key Attacks | Vulnerable to attacks when keys share common prefixes or patterns (WEP vulnerability) | DO NOT USE - Algorithm fundamentally broken |
| Broadcast Attacks | Statistical analysis of multiple ciphertexts can recover plaintext patterns | DO NOT USE - Officially deprecated by RFC 7465 |
3 vectors ship with this algorithm and run in the test suite. Byte values are hexadecimal.
Vector 1 — RFC 6229 Test Vector (40-bit key)
| Field | Value |
|---|---|
key |
0102030405 |
input |
0000000000000000 |
expected |
b2396305f03dc027 |
Vector 2 — RFC 6229 Test Vector (128-bit key)
| Field | Value |
|---|---|
key |
0102030405060708090a0b0c0d0e0f10 |
input |
0000000000000000 |
expected |
9ac7cc9a609d1ef7 |
Vector 3 — RFC 6229 Test Vector (256-bit key)
| Field | Value |
|---|---|
key |
0102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f20 |
input |
0000000000000000 |
expected |
eaa6bd25880bf93d |