Hawkynt

Fubuki (DarkCrypt)

Fubuki stream/block cipher built on an untempered Mersenne Twister (MT19937) generator: the key and initial value seed MT19937, whose raw output words pseudorandomly select and parameterize nine primitive encryption functions (four word-wise, four inter-word, one vertical-rotate) applied over four rounds per 128-bit block. DarkCrypt’s “Fubuki (512 bit)” build fixes both the key and the initial value at 512 bits.

Properties

Property	Value
Category	Stream Ciphers
Sub-category	Stream Cipher
Security status	🎓 Educational Only
Complexity	Advanced
Inventor	Makoto Matsumoto, Takuji Nishimura, Mariko Hagita, Mutsuo Saito; DarkCrypt build by Alexander Myasnikov
Year	2005
Origin	🇯🇵 Japan
Source	algorithms/stream/darkcrypt-fubuki.js

Parameters

Parameter	Supported values
Key sizes	64 bytes (512 bits)
Nonce sizes	64 bytes (512 bits)

Security

Status: 🎓 Educational Only

No vulnerabilities are recorded for this implementation.

Documentation

• Mersenne Twister and Fubuki Stream/Block Cipher (original eSTREAM submission)
• Cryptographic Mersenne Twister and Fubuki Stream/Block Cipher (extended version, IACR ePrint 2005/165)
• eSTREAM CryptMT/Fubuki submission page

References

• DarkCrypt / Zarya Total Commander plugin

Test vectors

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

Vector 1 — DarkCrypt Fubuki - 512-bit key, zero initial value, 128 zero bytes

Field	Value
key	000102030405060708090a0b0c0d0e0f 101112131415161718191a1b1c1d1e1f 202122232425262728292a2b2c2d2e2f 303132333435363738393a3b3c3d3e3f
iv	00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000
input	00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000
expected	e7a824ba3c50c8a7d88a534fae0aeacf 32a9e53a484b1ffd549ad8c24a1538e4 4ca2fcbc3d3d07d4f66238ec0786188a d559f1865b4d15937667934eef3dd1e2 83597c6c1792b3c0ac235173e4099100 617534faf737aa1bcdbe8c3e2cdcf6dd 8491da13d6b8da73868d5398f794d5ea c3df453d348b4efcec187694bbd13882

Vector 2 — DarkCrypt Fubuki - 512-bit key, zero initial value, incrementing 64-byte input (fresh setup)

Field	Value
key	000102030405060708090a0b0c0d0e0f 101112131415161718191a1b1c1d1e1f 202122232425262728292a2b2c2d2e2f 303132333435363738393a3b3c3d3e3f
iv	00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000
input	000102030405060708090a0b0c0d0e0f 101112131415161718191a1b1c1d1e1f 202122232425262728292a2b2c2d2e2f 303132333435363738393a3b3c3d3e3f
expected	f8876dc89d3331a7bef5e9dcf2860402 b6a9a38864cbf13d65df3c30e312a643 c33516aa4d26eb44a44680d36582da86 de579aea2e88eeb788343c2991b9f07f

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