MultiSwap

MultiSwap
General
Designers	Microsoft
First published	April 1999
Cipher detail
Key sizes	374 bits
Block sizes	64 bits
Best public cryptanalysis
The differential cryptanalysis of Borisov, et al. requires about 2¹³ chosen plaintexts or about 2²² known plaintexts

In cryptography, MultiSwap is a block cipher/MAC created by Microsoft in 1999 as part of its Windows Media DRM service (WMDRM). Microsoft's internal name for the algorithm is not publicly known; it was dubbed MultiSwap in a 2001 report on WMDRM under the pseudonym "Beale Screamer".

The cipher has a block size of 64 bits, but the two halves are processed nearly separately. All arithmetic operations are performed mod 2³². In the encryption process, each half block has added to it the output of the previous half block. Next it undergoes 5 multiplications by odd 32-bit subkeys, each followed by a swap of its 16-bit halves. Then a final subkey is added to it. As the half blocks use separate subkeys, and the multipliers are forced to be odd, the total key size is 374 bits. The name MultiSwap comes from the cipher's multiplications and swaps. WMDRM uses this algorithm only as a MAC, never for encryption.

Borisov, et al. applied a multiplicative form of differential cryptanalysis to break MultiSwap.

References

Beale Screamer (18 October 2001). "Microsoft's Digital Rights Management Scheme – Technical Details". Retrieved 20 September 2007.
Nikita Borisov, Monica Chew, Rob Johnson, David Wagner. "Cryptanalysis of MultiSwap". Retrieved 9 October 2010.
Borisov, Chew, Johnson, Wagner (February 2002). Multiplicative Differentials (PDF/PostScript). 9th International Workshop on Fast Software Encryption (FSE '02). Leuven: Springer-Verlag. pp. 17–33. Retrieved 3 January 2007.

Block ciphers (security summary)

Common algorithms	AES Blowfish DES (Internal Mechanics, Triple DES) Serpent Twofish

Less common algorithms	Camellia CAST-128 IDEA RC2 RC5 RC6 SEED ARIA Skipjack TEA XTEA

Other algorithms	3-Way Akelarre Anubis BaseKing BassOmatic BATON BEAR and LION CAST-256 Chiasmus CIKS-1 CIPHERUNICORN-A CIPHERUNICORN-E CLEFIA CMEA Cobra COCONUT98 Crab Cryptomeria/C2 CRYPTON CS-Cipher DEAL DES-X DFC E2 FEAL FEA-M FROG G-DES GOST Grand Cru Hasty Pudding cipher Hierocrypt ICE IDEA NXT Intel Cascade Cipher Iraqi KASUMI KeeLoq KHAZAD Khufu and Khafre KN-Cipher Kuznyechik Ladder-DES Libelle LOKI (97, 89/91) Lucifer M6 M8 MacGuffin Madryga MAGENTA MARS Mercy MESH MISTY1 MMB MULTI2 MultiSwap New Data Seal NewDES Nimbus NOEKEON NUSH PRESENT Prince Q RC6 REDOC Red Pike S-1 SAFER SAVILLE SC2000 SHACAL SHARK Simon SM4 Speck Spectr-H64 Square SXAL/MBAL Threefish Treyfer UES Xenon xmx XXTEA Zodiac

Design	Feistel network Key schedule Lai-Massey scheme Product cipher S-box P-box SPN Avalanche effect Block size Key size Key whitening (Whitening transformation)

Attack (cryptanalysis)	Brute-force (EFF DES cracker) MITM (Biclique attack, 3-subset MITM attack) Linear (Piling-up lemma) Differential (Impossible Truncated Higher-order) Differential-linear Distinguishing (Known-key) Integral/Square Boomerang Mod n Related-key Slide Rotational Timing XSL Interpolation Partitioning Davies' Rebound Weak key Tau Chi-square Time/memory/data tradeoff

Standardization	AES process CRYPTREC NESSIE

Utilization	Initialization vector Mode of operation Padding

Cryptography

History of cryptography Cryptanalysis Outline of cryptography

Symmetric-key algorithm Block cipher Stream cipher Public-key cryptography Cryptographic hash function Message authentication code Random numbers Steganography

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