Reduced-state variant of Py by Biham and Seberry: a 64-entry (6-bit) rolling permutation P and a 68-entry rolling word array Y, same round structure and two-word output as Py but far cheaper key/IV setup. Ported from the DarkCrypt Total Commander plugin, which hardcodes a 256-bit key and 256-bit IV.
| Property | Value |
|---|---|
| Category | Stream Ciphers |
| Sub-category | Rolling-Array Stream Cipher |
| Security status | Not classified |
| Complexity | Advanced |
| Inventor | Eli Biham, Jennifer Seberry |
| Year | 2005 |
| Origin | 🇮🇱 Israel |
| Source | algorithms/stream/darkcrypt-py6.js |
| Parameter | Supported values |
|---|---|
| Key sizes | 32 bytes (256 bits) |
| Nonce sizes | 32 bytes (256 bits) |
Status: not classified — treat as unverified.
| Issue | Description | Mitigation |
|---|---|---|
| Distinguishing / key-recovery attacks | Py6 shares Py’s broken IV setup and was superseded by the tweaked TPy6. | Use TPy6 or a vetted modern cipher. |
1 vector ship with this algorithm and run in the test suite. Byte values are hexadecimal.
Vector 1 — DarkCrypt Py6 keystream
| Field | Value |
|---|---|
iv |
0000000000000000000000000000000000000000000000000000000000000000 |
key |
000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f |
input |
00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 |
expected |
76f4f37ef99618f05f6e37915b5f155b 11baa364135804add08f5993c755c704 b7fdc77ef8f8c05f290c039847874a90 2e043e337ecad27bdee53ecb4a1d9906 f9953c55c6c5847b11e6e8d129d96086 eb78d2980ae6554e3dafff17422681a4 ca95ac40d0fbe93c2263887d87a80d6d 9ff19933f6ca642fa56cbcc42f58269b |