Data Encryption Standard DES security

Even though DES Cryptanalysis has more information than other block ciphers , But by far the most practical attack is still brute force .

Brute force attack

There's a lot about DES Password attack techniques have been made public , The brute force method is one of the most effective attacks ,

Brute force attack can be understood as the commonly known brute force attack , It usually appears when the user name and password are exploded , Once the existing user name is determined , Many attackers will try to return the size of the packet echo , Content, etc. , Crack the password through brute force attack , The length of the key determines the number of possible keys , This determines the feasibility of this method .

DES History of cracking machine

Neither of the following two early proposals has been publicly recognized ：

• 1977 year ,Diffie and Hellman A value of about 2000 A million dollar machine , Can be found in a day DES secret key .
• 1993 year ,Wiener Put forward a kind of value 100 Million dollar key search machine , Can be in 7 Key found within hours .

1990 In the late S, some people began to pay attention to DES The vulnerability of ,

• 1997 year ,RSA Security Sponsored a series of competitions , To the first crack game DES The team that encrypts the message provides 10,000 Dollar bonus .
• Quick crack DES The feasibility of 1998 It was confirmed in , At that time, the Electronic Frontier Foundation, a civil rights organization in cyberspace (EFF) Built a custom DES Cracker , The cost is about 250,000 dollar .

 

• 2006 Developed by the teams of Bohong University and Kiel University in DES The cracker was built in Germany COPACOBANA machine .
  COPACOBANA Commercially available 、 Reconfigurable integrated circuit composition ,COPACOBANA The cost of a machine is about 10,000 dollar , And EFF Compared with machines , The cost has been reduced by about 25 times , This is an example of the continuous improvement of digital hardware .

Differential cryptanalysis (DC)

Eli Biham and Adi Shamir stay 1980 It was rediscovered in the late s DC（ Differential cryptanalysis ）, To crack the complete 16 round , Differential cryptanalysis requires 2 Of 47 To the power of a choice of plaintext ,DES Designed to resist DC.

Linear cryptanalysis (LC)

Mitsuru Matsui Linear cryptanalysis was discovered (LC), This technology requires 2 Of 43 Power known plaintext , Was the first to be reported DES Experimental cryptanalysis .

Davies attack

80 years ,Donald Davies For the first time Davies attack ,Davies An attack is a specialized DES Technology is also a technology that only applies to DES Special attacks on （LC and DC It belongs to a general attack of many algorithms ）.
Davies The attack requires 2 Of 50 Power known plaintext , The success rate is about 51%.