Hawkynt

ISAAC (DarkCrypt)

Bob Jenkins’s ISAAC PRNG wrapped as a stream cipher by the DarkCrypt Total Commander plugin. Seeds from a full 1024-byte state buffer, discards 256 extra rounds during setup, and XORs raw little-endian keystream bytes.

Properties

Property	Value
Category	Stream Ciphers
Sub-category	Stream Cipher
Security status	🎓 Educational Only
Complexity	Intermediate
Inventor	Bob Jenkins (base ISAAC design); DarkCrypt wrapper by Alexander Myasnikov
Year	2013
Origin	🇷🇺 Russia
Source	algorithms/stream/darkcrypt-isaac.js

Parameters

Parameter	Supported values
Key sizes	1024 bytes (8192 bits)
Block sizes	1 byte (8 bits) to 65536 bytes (524288 bits)

Security

Status: 🎓 Educational Only

Known vulnerabilities

Issue	Description	Mitigation
Non-standard wrapper	Uses the unmodified ISAAC core but a bespoke setup/crypt protocol; unanalyzed and not recommended for real use.	Use a vetted stream cipher.

Documentation

• DarkCrypt plugin (Total Commander PlugRing)
• ISAAC Homepage - Bob Jenkins

Test vectors

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

Vector 1 — DarkCrypt Isaac — 1024-byte incrementing seed, zero input

Field	Value
key	000102030405060708090a0b0c0d0e0f 101112131415161718191a1b1c1d1e1f 202122232425262728292a2b2c2d2e2f 303132333435363738393a3b3c3d3e3f … (1024 bytes; the full value is in the source)
input	00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000
expected	c86ae56681b5ff86a91004199a995a5c 8d699a0f454b79a250401a4b6e0acee3 8e2c8beea25b40270f18903e25622020 caffb586a47b679e47b7961c2173db60 f6672ae9fbeebe295aacc2812b27cec5 6d046bcbf4c5868ee2bcb0db5e56f237 81efcdd0e2f5d6eebcef2baae8756a09 005646a53684c5c8ff42cd0ed0a31342

Vector 2 — DarkCrypt Isaac — 1024-byte incrementing seed, incrementing plaintext

Field	Value
key	000102030405060708090a0b0c0d0e0f 101112131415161718191a1b1c1d1e1f 202122232425262728292a2b2c2d2e2f 303132333435363738393a3b3c3d3e3f … (1024 bytes; the full value is in the source)
input	000102030405060708090a0b0c0d0e0f 101112131415161718191a1b1c1d1e1f 202122232425262728292a2b2c2d2e2f 303132333435363738393a3b3c3d3e3f
expected	c86be76585b0f981a1190e1296945453 9d78881c515e6fb5485900507217d0fc ae0da9cd867e66002731ba15094f0e0f face87b5904e51a97f8eac271d4ee55f

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