1. The Data Encryption Standard (DES) By Danny Gibbs 4/19/2005

2. Realization in 1970’s  Communication  Would rely on computers  A standard needed to ensure protection  tested and published

3. National Bureau of Standards  May 15, 1973  Federal Register notice  Asked Science and Industry to submit algorithms

4. Algorithm Criteria  Provide high level of security  Completely specified and easy to understand  Key based security; not in secrecy of algorithm  Available to all users  Adaptable  Economically implemented  Efficient  Must be validated  Exportable

5. IBM  August 6, 1974  Submitted algorithm named Lucifer  Based on mixing transpositions and substitutions  Only algorithm to match all criteria  17 man-years of effort into creating and analyzing the algorithm

6. Testing The Algorithm  NSA enlisted  Cryptographic expertise  Security authority

7. A Standard is Born  First official description  Published: January 15, 1977  Algorithm became  The Data Encryption Standard  July 15, 1977  Federal Information Processing Standards Publication  46 (initial publication)  46-3 (current version, 1999)

8. New Era in Cryptography  DES  First  published algorithm  algorithm asking for public scrutiny  NSA-evaluated algorithm to be published  Cryptography  Growing field  Had an NSA-evaluated algorithm to work with

9. Criticisms  Why involve NSA?  Possible trapdoors  Decrypt any message  Matter investigated  U.S. Senate Select Committee on Intelligence  1978  Found no tampering done by NSA

10. Criticisms (2)  NSA involvement  Ensure IBM did not implement trapdoors  Keys  Weak Keys  Semiweak Keys  Possibly weak Keys  Listed in Applied Cryptography by Bruce Schneier

11. Criticisms (3)  Key Length  Originally 112-bit but reduced  Now 56-bit Key  Studies in 1977 showed a brute force attack would cost $50-$200 million to implement  Considered not a possibility  So standard 56-bits

12. Today and DES  FIPS PUB 46-3  Recommends using Triple-DES  Brute force of DES easily possible  New systems implemented with Triple-DES

13. Triple-DES  Based on DES  Encryption  Input => DES E key1 => DES D key2 => DES E key3 => Output  Decryption  Input => DES D key3 => DES E key2 => DES D key1 => Output

14. Conclusion  DES algorithm  Changed cryptography  Many firsts  Still being used as part of Triple-DES  Thirty years later  Important to history of Cryptography

15. Works Cited  Beker, Henry, and Fred Piper. Cipher Systems: The Protection of Communications. New York: Wiley, 1982.  Daley, William M., U.S. Department of Commerce, Secretary. Kammer, Raymond G., National Institute of Standards and Technology, Director. Data Encryption Standard (DES). Federal Information Processing Standards Publication 46-3. Gaithersburg, MD. 1999 October 25.  Menezes, Alfred, Paul van Oorschot, and Scott Vanstone. Handbook of Applied Cryptography. New York: CRC, 1997.  Meyer, Carl, and Stephen Matyas. Cryptography: A New Dimenson In Computer Data Security: A Guide for the Design and Implementation of Secure Systems. New York: Wiley, 1982.  Patterson, Wayne. Mathematical Cryptology for Computer Scientists and Mathematicians. Totowa, NJ: Rowman & Littlefield, 1987.  Schneier, Bruce. Applied Cryptography: protocols, algorithms, and source code in C. New York: Wiley, 1996.