Hawkynt

Fcrypt-EDE (DarkCrypt)

3-key Encrypt-Decrypt-Encrypt composition of “Fcrypt”, a DES-inspired 64-bit block cipher from the DarkCrypt Total Commander plugin. The 192-bit key splits into three independent 64-bit Fcrypt subkeys Kc/Ka/Kb; crypt(block) = Encrypt(Decrypt(Encrypt(block,Kc),Ka),Kb). The inner cipher is a 16-round alternating Feistel network using four 256-entry 32-bit lookup tables per round and a DES-style (parity-bit-dropping) key schedule.

Properties

Property	Value
Category	Block Ciphers
Sub-category	Block Cipher
Security status	🎓 Educational Only
Complexity	Intermediate
Inventor	Unknown (DarkCrypt plugin author: Alexander Myasnikov)
Year	2006
Origin	🇷🇺 Russia
Source	algorithms/block/darkcrypt-fcrypt.js

Parameters

Parameter	Supported values
Key sizes	24 bytes (192 bits)
Block sizes	8 bytes (64 bits)

Security

Status: 🎓 Educational Only

Known vulnerabilities

Issue	Description	Mitigation
Non-standard, unanalyzed cipher	No public specification exists for this cipher; the base cipher and its EDE composition have not been subjected to public cryptanalysis.	Use AES or another vetted cipher.
Meet-in-the-middle	Triple-EDE constructions built from a 64-bit-block cipher offer materially less than 3x the effective key strength against meet-in-the-middle attacks.	Prefer a modern wide-block cipher such as AES-256.

Documentation

• DarkCrypt plugin (Total Commander PlugRing)
• EDE (Encrypt-Decrypt-Encrypt) composition

Test vectors

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

Vector 1 — DarkCrypt Fcrypt — zero key/plaintext

Field	Value
key	000000000000000000000000000000000000000000000000
input	0000000000000000
expected	0e0900c73ef7ed41

Vector 2 — DarkCrypt Fcrypt — incrementing key/plaintext

Field	Value
key	000102030405060708090a0b0c0d0e0f1011121314151617
input	0001020304050607
expected	669264ffa9c6239a

Vector 3 — DarkCrypt Fcrypt — shifted incrementing key/plaintext

Field	Value
key	0102030405060708090a0b0c0d0e0f101112131415161718
input	1011121314151617
expected	8bdb7d0bfb37291c

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