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Cryptography

 Award plaque by D. Coppersmith

This paper is concerned with two aspects of cryptography in which the author has been working. One is the Data Encryption Standard (DES), developed at IBM and now in wide use for commercial cryptographic applications. This is a “private key” system; the communicants share a secret key, and the eavesdropper will succeed if he can guess this key among its quadrillions of possibilities. The other is the Diffie–Hellman key exchange protocol, a typical “public key” cryptographic system. Its security is based on the difficulty of taking “discrete logarithms”  (reversing the process of exponentiation in a finite field). We describe the system and some analytic attacks against it.

Originally published:

IBM Journal of Research and Development, Volume 31, Issue 2, pp. 244-248 (1987).

Significance:

This paper describes key aspects of data encryption systems and the Data Encryption Standard (DES) which was developed by IBM in 1973–1974. This paper presents an overview of this method. The Data Encryption Standard is a cipher (a method for encrypting information) which was selected as an official Federal Information Processing Standard (FIPS) for the United States in 1976 and has subsequently enjoyed widespread use internationally. Following this key paper improvements to DES such as triple-DES [A proposed mode for triple-DES encryption (JRD 1996)] were invented to ensure that encryption systems could not be broken by even the best cryptanalysts.

Comments:

Related paper: A proposed mode for triple-DES encryption  (JRD 1996) by D. Coppersmith, D. B. Johnson, and S. M. Matyas

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