DATA ENCRYPTION STANDARD

1
DATA ENCRYPTION STANDARD

• Shirley Ann Fogarty
• Pat OCallaghan

• Karen Waters
• Eoin Cosgrave

2
Introduction to DES

• DES was developed by IBM and was endorsed by the
  US government in 1977 as an official standard.
• DES is an encryption block cipher that encrypts
  data in 64-bit blocks.
• When in use, both the receiver and the sender
  must use the same key for encryption and
  decryption.

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Description of DES

• Main Components Algorithm and key
• 64 - bit block of plaintext enters algorithm.
• Split in half, combined with the key and 16
  identical rounds are performed on it.
• 64-bit block of ciphertext is produced from the
  algorithm.

4
History of DES

• National Bureau of Standards (NBS) wanted a
  program to protect computer and communications
  data .
• IBM developed an algorithm from an old algorithm
  called Lucifer.
• The response from the public was good yet wary
  due to the involvement of the NSA.

5
History of DES

• Official description, Data Encryption Standard,
  published January 15, 1977.
• DES is reviewed every 5 years.
• To this day no suitable replacement algorithm has
  been found.

6
Security of DES

• DES is expected to have a backdoor in the
  algorithm.
• There are 64 weak keys and when used for the
  initial keys can cause security problems.
• There are rumors that a computer has been built
  which can crack it in 3 hours.

7
Variations on DES

• Multiple DESThe algorithm is applied several
  times
• Tuchman developed a method known as Triple
  Encryption with Two Keys (EDE mode)
• Doubling the block length128 vs. 64 bit block
  pros and cons

8
Uses in Software

• DES The algorithm of choice
• Users include IBM, Motorola and General Electric
• DES based products include mobile radio units and
  encryption boxes for use with microwave,
  satellite and other types of communications

9
Politics

• Several cryptographers have brought lawsuits
  against the U.S Government.
• Between the 1970s and 1990s NSA threatened
  people with prosecution if they published certain
  scientific papers
• 1996 saw a decision that no attempts should be
  made to regulate publications in books or any
  form of paper .

10
Future According To IBM

• On 1/7/98, IBM submitted a new encryption
  algorithm to NIST for consideration as the AES
• It has a 128-bit key, and can be used in
  hardware, software and in bandwidth-constrained
  applications i.e smart cards.
• Although DES is still a strong encryption
  algorithm NIST is said to be preparing for its
  eventual replacement.