EFF DES cracker

The EFF's US$250,000 DES cracking machine contained 1,856 custom chips and could brute force a DES key in a matter of days — the photo shows a two-sided DES Cracker circuit board fitted with 64 Deep Crack chips

In cryptography, the EFF DES cracker (nicknamed "Deep Crack") is a machine built by the Electronic Frontier Foundation (EFF) in 1998, to perform a brute force search of DES cipher's key space – that is, to decrypt an encrypted message by trying every possible key. The aim in doing this was to prove that DES's key was not long enough to be secure.

Background

DES uses a 56-bit key, meaning that there are 2⁵⁶ possible keys under which a message can be encrypted. This is exactly 72,057,594,037,927,936, or approximately 72 quadrillion possible keys. One of the major criticisms of DES, when proposed in 1975, was that the key size was too short. Martin Hellman and Whitfield Diffie of Stanford University estimated that a machine fast enough to test that many keys in a day would have cost about $20 million in 1976, an affordable sum to national intelligence agencies such as the US National Security Agency.^[1] Subsequent advances in the price/performance of chips kept reducing that cost until twenty years later it became affordable to even a small nonprofit organization such as the EFF.^[2]

The DES challenges

DES was a federal standard, and the US government encouraged the use of DES for all non-classified data. RSA Security wished to demonstrate that DES's key length was not enough to ensure security, so they set up the DES Challenges in 1997, offering a monetary prize. The first DES Challenge was solved in 96 days by the DESCHALL Project led by Rocke Verser in Loveland, Colorado. RSA Security set up DES Challenge II-1, which was solved by distributed.net in 39 days in January and February 1998.^[3]

The EFF's DES cracker "Deep Crack" custom microchip

In 1998, the EFF built Deep Crack for less than $250,000.^[4] In response to DES Challenge II-2, on July 15, 1998, Deep Crack decrypted a DES-encrypted message after only 56 hours of work, winning $10,000. This was the final blow to DES, against which there were already some published cryptanalytic attacks. The brute force attack showed that cracking DES was actually a very practical proposition. Most governments and large corporations could reasonably build a machine like Deep Crack.

Six months later, in response to RSA Security's DES Challenge III, and in collaboration with distributed.net, the EFF used Deep Crack to decrypt another DES-encrypted message, winning another $10,000. This time, the operation took less than a day – 22 hours and 15 minutes. The decryption was completed on January 19, 1999. In October of that year, DES was reaffirmed as a federal standard, but this time the standard recommended Triple DES.

The small key-space of DES, and relatively high computational costs of Triple DES resulted in its replacement by AES as a Federal standard, effective May 26, 2002.

Technology

Deep Crack was designed by Cryptography Research, Inc., Advanced Wireless Technologies, and the EFF. The principal designer was Paul Kocher, president of Cryptography Research. Advanced Wireless Technologies built 1856 custom ASIC DES chips (called Deep Crack or AWT-4500), housed on 29 circuit boards of 64 chips each. The boards were then fitted in six cabinets and mounted in a Sun-4/470 chassis.^[5] The search was coordinated by a single PC which assigned ranges of keys to the chips. The entire machine was capable of testing over 90 billion keys per second. It would take about 9 days to test every possible key at that rate. On average, the correct key would be found in half that time.

In 2006, another custom hardware attack machine was designed based on FPGAs. COPACOBANA (COst-optimized PArallel COdeBreaker) is able to crack DES at considerably lower cost.^[6] This advantage is mainly due to progress in integrated circuit technology. In July 2012, security researchers David Hulton and Moxie Marlinspike unveiled a cloud computing tool for breaking the MS-CHAPv2 protocol by recovering the protocol's DES encryption keys by brute force. This tool effectively allows members of the general public to recover a DES key from a known plaintext-ciphertext pair in about 24 hours.^[7]

References

External links

Wikimedia Commons has media related to EFF DES cracker.

• The DES Cracker page on EFF's site
• Photos of the machine on Cryptography Research's site
• COPACOBANA, an off-the-shelf DES cracking device

Block ciphers (security summary) Common algorithms AES Blowfish DES (Internal Mechanics, Triple DES) Serpent Twofish Less common algorithms Camellia CAST-128 IDEA RC2 RC5 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 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 Q RC6 REDOC Red Pike S-1 SAFER SAVILLE SC2000 SHACAL SHARK Simon SMS4 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 Portal