Hawkynt

SEAL2 (DarkCrypt)

Rogaway/Coppersmith SEAL variant from the DarkCrypt Total Commander plugin: SHA-0-shaped table generation (T[512]/S[256]/R[16]) from a 160-bit key, a table-driven round mixing a/b/c/d, and additive-only periodic re-mixing of just two of the four state words. Identical output confirmed from the plugin’s related SEAL variant.

Properties

Property	Value
Category	Stream Ciphers
Sub-category	Stream Cipher
Security status	🎓 Educational Only
Complexity	Advanced
Inventor	Phil Rogaway, Don Coppersmith (DarkCrypt variant by Alexander Myasnikov)
Year	1994
Origin	🇷🇺 Russia
Source	algorithms/stream/darkcrypt-seal2.js

Parameters

Parameter	Supported values
Key sizes	20 bytes (160 bits)
Block sizes	1 byte (8 bits) to 65536 bytes (524288 bits)

Security

Status: 🎓 Educational Only

Known vulnerabilities

Issue	Description	Mitigation
Non-standard construction	DarkCrypt’s SEAL2 variant deviates from the published SEAL round structure (partial state re-mixing, non-standard table hash); not vetted, not recommended for real use.	Use a vetted stream cipher.

Documentation

• SEAL Specification (FSE’94)
• DarkCrypt plugin (Total Commander PlugRing)

Test vectors

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

Vector 1 — DarkCrypt Seal2 — keystream from incrementing key, zero input

Field	Value
key	000102030405060708090a0b0c0d0e0f10111213
input	00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000
expected	d95030a48b03db75c9b45cf849d659e4 43df9aae2e1695a0ba8ea72be7aa37c4 940291d21e585a8d1aadcf142de6d000 6df1cc6fae1c08778a4b033ef90a80c0 ae89ad2e21c0c56936bb2004d5aff917 3164ecd8b47ea23816875981ec67cd9e 1d75612eab874ef2fcaa9400e4c4c1d8 5a1e63c80592a764cb886ddc4072ec4c

Vector 2 — DarkCrypt Seal — keystream from incrementing key, zero input (byte-identical to with the same key)

Field	Value
key	000102030405060708090a0b0c0d0e0f10111213
input	00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000
expected	d95030a48b03db75c9b45cf849d659e4 43df9aae2e1695a0ba8ea72be7aa37c4 940291d21e585a8d1aadcf142de6d000 6df1cc6fae1c08778a4b033ef90a80c0 ae89ad2e21c0c56936bb2004d5aff917 3164ecd8b47ea23816875981ec67cd9e 1d75612eab874ef2fcaa9400e4c4c1d8 5a1e63c80592a764cb886ddc4072ec4c

Vector 3 — DarkCrypt Seal2 — incrementing key/plaintext

Field	Value
key	000102030405060708090a0b0c0d0e0f10111213
input	000102030405060708090a0b0c0d0e0f 101112131415161718191a1b1c1d1e1f 202122232425262728292a2b2c2d2e2f 303132333435363738393a3b3c3d3e3f
expected	d95132a78f06dd72c1bd56f345db57eb 53ce88bd3a0383b7a297bd30fbb729db b423b3f13a7d7caa3284e53f01cbfe2f 5dc0fe5c9a293e40b2723905c537beff

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