Py (“Roo”) eSTREAM Phase 2 candidate by Biham and Seberry, using two rolling arrays (a 260-word Y array and a 256-byte permutation P) indexed by a continuously advancing round counter. Ported from the DarkCrypt Total Commander plugin, which hardcodes a 512-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-py.js |
| Parameter | Supported values |
|---|---|
| Key sizes | 64 bytes (512 bits) |
| Nonce sizes | 32 bytes (256 bits) |
Status: not classified — treat as unverified.
| Issue | Description | Mitigation |
|---|---|---|
| Distinguishing / key-recovery attacks | Wu and Preneel, and others, broke Py’s IV setup with chosen-IV attacks; superseded by the tweaked TPy. | Use TPy or a vetted modern cipher. |
1 vector ship with this algorithm and run in the test suite. Byte values are hexadecimal.
Vector 1 — DarkCrypt Py keystream
| Field | Value |
|---|---|
iv |
0000000000000000000000000000000000000000000000000000000000000000 |
key |
000102030405060708090a0b0c0d0e0f 101112131415161718191a1b1c1d1e1f 202122232425262728292a2b2c2d2e2f 303132333435363738393a3b3c3d3e3f |
input |
00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 |
expected |
2d92f053176f06e956c924da00218c5a 84f2c9e513def4ea5785c7ee8aea32e1 c190fcecf208b72ae5a2f2b1c8e801fe 1a93785ea5ef503ecd159c0757e40e50 910c8ab04f8116711ce1431f6c2f040a 1b80e3c158689230dcbb6db3d32e53f5 d7f67bea16441e6adbb581e7f0aa4e40 a12f269bddd280ac345fbb0a2cde8628 |