Hawkynt

ChaCha8 (DarkCrypt)

Reduced-round (8-round) ChaCha variant with the original Bernstein state layout (64-bit block counter + 64-bit nonce, instead of RFC 7539’s 32-bit counter + 96-bit nonce). Matches the DarkCrypt Total Commander plugin’s ChaCha implementation.

Properties

Property	Value
Category	Stream Ciphers
Sub-category	Stream Cipher
Security status	🎓 Educational Only
Complexity	Intermediate
Inventor	Daniel J. Bernstein (base cipher); DarkCryptTC (parameterization)
Year	2008
Origin	🇺🇸 United States
Source	algorithms/stream/darkcrypt-chacha8.js

Parameters

Parameter	Supported values
Key sizes	32 bytes (256 bits)
Block sizes	1 byte (8 bits) to 65536 bytes (524288 bits)
Nonce sizes	8 bytes (64 bits)

Security

Status: 🎓 Educational Only

No vulnerabilities are recorded for this implementation.

Documentation

• Bernstein: ChaCha, a variant of Salsa20
• RFC 7539: ChaCha20 and Poly1305 for IETF Protocols (for comparison)
• DarkCrypt plugin (Total Commander PlugRing)

References

• Bernstein’s Original ChaCha Reference Implementation (eSTREAM submission)
• DarkCryptTC

Test vectors

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

Vector 1 — DarkCrypt Chacha - 128-byte keystream (key=00..1F, nonce=0)

Field	Value
key	000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f
nonce	0000000000000000
input	00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000
expected	4015b28f6e12ab6ad9e8667b31c51233 f78f172790b2d94f326b2ed7ffbcbecb ff9ead365f89ce3b6f4055bc759d90fd 8f831d27c7b0df93b3b9ed8238a256d6 761a6e0fc8b2b859f5a9f3ae170a7599 b0b023ce79d7659b32ee79373e727289 712ff289f30f641fcd822ff8e656ffd8 725691f839a7b433a5b61053d99baee0

Vector 2 — DarkCrypt Chacha - enc of 00..3F (key=00..1F, nonce=0)

Field	Value
key	000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f
nonce	0000000000000000
input	000102030405060708090a0b0c0d0e0f 101112131415161718191a1b1c1d1e1f 202122232425262728292a2b2c2d2e2f 303132333435363738393a3b3c3d3e3f
expected	4014b08c6a17ad6dd1e16c703dc81c3c e79e053484a7cf582a7234cce3a1a0d4 dfbf8f157bace81c47697f9759b0bed2 bfb22f14f385e9a48b80d7b9049f68e9

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