Stephen Pohlig (1953-April 14, 2017) was an electrical engineer who worked in the

MIT Lincoln Laboratory The MIT Lincoln Laboratory, located in Lexington, Massachusetts, is a United States Department of Defense federally funded research and development center chartered to apply advanced technology to problems of national security. Research and dev ...

. As a graduate student of

Martin Hellman Martin Edward Hellman (born October 2, 1945) is an American cryptologist and mathematician, best known for his involvement with public key cryptography in cooperation with Whitfield Diffie and Ralph Merkle. Hellman is a longtime contributor to th ...

's at

Stanford University Stanford University, officially Leland Stanford Junior University, is a private research university in Stanford, California. The campus occupies , among the largest in the United States, and enrolls over 17,000 students. Stanford is consider ...

in the mid-1970s, he helped develop the underlying concepts of Diffie-Hellman key exchange, including the Pohlig–Hellman exponentiation cipher and the

Pohlig–Hellman algorithm In group theory, the Pohlig–Hellman algorithm, sometimes credited as the Silver–Pohlig–Hellman algorithm, Mollin 2006, pg. 344 is a special-purpose algorithm for computing discrete logarithms in a finite abelian group whose order is a smooth ...

Oral history interview with Martin Hellman
2004, Palo Alto, California.

Charles Babbage Institute The IT History Society (ITHS) is an organization that supports the history and scholarship of information technology by encouraging, fostering, and facilitating archival and historical research. Formerly known as the Charles Babbage Foundation, ...

, University of Minnesota, Minneapolis. for computing

discrete logarithm In mathematics, for given real numbers ''a'' and ''b'', the logarithm log''b'' ''a'' is a number ''x'' such that . Analogously, in any group ''G'', powers ''b'k'' can be defined for all integers ''k'', and the discrete logarithm log''b' ...

s. That cipher can be regarded as a predecessor to the

RSA (cryptosystem) RSA (Rivest–Shamir–Adleman) is a public-key cryptography, public-key cryptosystem that is widely used for secure data transmission. It is also one of the oldest. The acronym "RSA" comes from the surnames of Ron Rivest, Adi Shamir and Leona ...

since all that is needed to transform it into RSA is to change the arithmetic from modulo a prime number to modulo a composite number. In his spare time Stephen Pohlig was a keen kayaker known to many throughout the New England area.

Bibliography

* S. Pohlig and M. Hellman, "An improved algorithm for computing logarithms over GF(p) and its cryptographic significance (Corresp.)," Information Theory, IEEE Transactions on 24, no. 1 (1978): 106-110. * Martin E. Hellman and Stephen C. Pohlig,
United States Patent: 4424414 - Exponentiation cryptographic apparatus and method
" January 3, 1984. * Boston Globe Obituary, "http://www.legacy.com/obituaries/bostonglobe/obituary.aspx?n=stephen-c-pohlig&pid=185155411&fhid=20778"

References

American electrical engineers Living people MIT Lincoln Laboratory people Computer security academics 1953 births {{US-electrical-engineer-stub