Hawkynt

A5 (DarkCrypt)

A5-family stop/go three-LFSR stream cipher from the DarkCrypt Total Commander plugin. Loads the 64-bit key directly into the registers (no frame number, no discard rounds) and uses non-standard clock-control/tap positions.

Properties

Property	Value
Category	Stream Ciphers
Sub-category	Stream Cipher
Security status	🎓 Educational Only
Complexity	Beginner
Inventor	ETSI SAGE (base A5/1 design); DarkCrypt variant by Alexander Myasnikov
Year	2013
Origin	🇷🇺 Russia
Source	algorithms/stream/darkcrypt-a5.js

Parameters

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

Security

Status: 🎓 Educational Only

Known vulnerabilities

Issue	Description	Mitigation
Non-standard variant	Modified A5/1 with a trivial direct key-load and altered tap positions; unanalyzed and not recommended for real use.	Use a vetted stream cipher.

Documentation

• DarkCrypt plugin (Total Commander PlugRing)
• Wikipedia: A5/1 (base algorithm)

Test vectors

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

Vector 1 — DarkCrypt A5 — keystream from incrementing key, zero input

Field	Value
key	0001020304050607
input	00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000
expected	fd65ae4da3a3dcbc8e1c52a8c7fb387a f2644f41e2f17eee773c526206c56dcb 50c51d253501f6959bb1b3572df82b8d 93b40aa3b907ce02e6d9bdcf5975e5b2 8762ee187a9c71e40c5db01eca4136cd 74acbd1779e1301edc07ebf25300a9f4 c327f5806c2065ad0d6a32aa6f2589d3 e040888e0ccb7d683ad91905e99dcadb

Vector 2 — DarkCrypt A5 — incrementing key/plaintext

Field	Value
key	0001020304050607
input	000102030405060708090a0b0c0d0e0f 101112131415161718191a1b1c1d1e1f 202122232425262728292a2b2c2d2e2f 303132333435363738393a3b3c3d3e3f
expected	fd64ac4ea7a6dabb861558a3cbf63675 e2755d52f6e468f96f2548791ad873d4 70e43f061124d0b2b398997c01d505a2 a38538908d32f835dee087f46548db8d

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