TPy6 (DarkCrypt)
Tweaked-IV-setup variant of Py6 by Biham and Seberry (2007): same reduced-state key setup and round function as Py6, but the IV mixing derives a doubled-width feedback buffer and folds mixed bytes back into later rounds, removing the equivalent-IV weakness. As implemented in the DarkCrypt Total Commander plugin, which hardcodes a 512-bit key and 256-bit IV.
Properties
| Property |
Value |
| Category |
Stream Ciphers |
| Sub-category |
Rolling-Array Stream Cipher |
| Security status |
❌ Broken |
| Complexity |
Advanced |
| Inventor |
Eli Biham, Jennifer Seberry |
| Year |
2007 |
| Origin |
🇮🇱 Israel |
| Source |
algorithms/stream/darkcrypt-tpy6.js |
Parameters
| Parameter |
Supported values |
| Key sizes |
64 bytes (512 bits) |
| Nonce sizes |
32 bytes (256 bits) |
Security
Status: ❌ Broken
Known vulnerabilities
| Issue |
Description |
Mitigation |
| Distinguishing / key-recovery attacks |
Sekar, Paul and Preneel published attacks on TPy6’s keystream generation and proposed further redesigns (TPy6-A/B). |
Use a vetted modern cipher. |
Documentation
References
Test vectors
2 vectors ship with this algorithm and run in the test suite. Byte values are hexadecimal.
Vector 1 — DarkCrypt TPy6 keystream
| Field |
Value |
iv |
0000000000000000000000000000000000000000000000000000000000000000 |
key |
000102030405060708090a0b0c0d0e0f 101112131415161718191a1b1c1d1e1f 202122232425262728292a2b2c2d2e2f 303132333435363738393a3b3c3d3e3f |
input |
00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 |
expected |
4ec12f0c0295bff2542946bafbcd0698 bfce5781b6e730547a0bd653c438f778 fa4150ff5a815d08d88e54a4d9158412 1ec60123ee8708f2fcafd257c677541e 1fa9fa5182aeda7d0fe0ae338b4933f0 8ba020d559a5a0650e283efdfaff8bf2 b3ed532b9882bc53749e1580469221cd c73489d2e9182ff380cda6b231e3eb66 |
Vector 2 — DarkCrypt TPy6 — non-zero key and IV, 48-byte message (verified against the DarkCrypt implementation)
| Field |
Value |
key |
0b30557a9fc4e90e33587da2c7ec1136 5b80a5caef14395e83a8cdf2173c6186 abd0f51a3f6489aed3f81d42678cb1d6 fb20456a8fb4d9fe23486d92b7dc0126 |
iv |
073c71a6db10457aafe4194e83b8ed22578cc1f62b6095caff34699ed3083d72 |
input |
03203d5a7794b1ceeb0825425f7c99b6 d3f00d2a4764819ebbd8f5122f4c6986 a3c0ddfa1734516e8ba8c5e2ff1c3956 |
expected |
7679d9f05c072ee6d9bbb6ab8292ac4f 908f6553b0aa8641c922d20bb3af6fbd 1ca1c17e4fc4da6c5539d079a59252a0 |
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