Hawkynt

Multiswap (DarkCrypt)

Microsoft’s MultiSwap block cipher/MAC (from Windows Media DRM / MS Reader .lit DRM), as wrapped into a standalone 64-bit block cipher by the DarkCrypt Total Commander plugin: the 56-byte key supplies 12 odd multiplicative subkeys plus a non-zero initial chaining state.

Properties

Property	Value
Category	Block Ciphers
Sub-category	Block Cipher
Security status	❌ Broken
Complexity	Intermediate
Inventor	Microsoft (documented/named by ‘Beale Screamer’); DarkCrypt wrapper by Alexander Myasnikov
Year	1999
Origin	🇺🇸 United States
Source	algorithms/block/darkcrypt-multiswap.js

Parameters

Parameter	Supported values
Key sizes	56 bytes (448 bits)
Block sizes	8 bytes (64 bits)

Security

Status: ❌ Broken

Known vulnerabilities

Issue	Description	Mitigation
Multiplicative differential cryptanalysis	Broken with about 2^14 chosen plaintexts or 2^22.5 known plaintexts (Borisov et al., FSE 2002).	Use AES or another vetted cipher.

Documentation

• DarkCrypt plugin (Total Commander PlugRing)
• MultiSwap (Wikipedia)
• Cryptanalysis of MultiSwap (Borisov, Chew, Johnson, Wagner)

Test vectors

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

Vector 1 — DarkCrypt Ms — zero key/plaintext

Field	Value
key	00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 0000000000000000
input	0000000000000000
expected	0200000003000000

Vector 2 — DarkCrypt Ms — incrementing key/plaintext

Field	Value
key	000102030405060708090a0b0c0d0e0f 101112131415161718191a1b1c1d1e1f 202122232425262728292a2b2c2d2e2f 3031323334353637
input	0001020304050607
expected	d0ad5c3a7eb8411c

Vector 3 — DarkCrypt Ms — shifted incrementing key/plaintext

Field	Value
key	0102030405060708090a0b0c0d0e0f10 1112131415161718191a1b1c1d1e1f20 2122232425262728292a2b2c2d2e2f30 3132333435363738
input	1011121314151617
expected	3a20b566b726024c

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