Stephen C. Pohlig (1952/1953 in

Washington, D.C. Washington, D.C., formally the District of Columbia and commonly known as Washington or D.C., is the capital city and federal district of the United States. The city is on the Potomac River, across from Virginia, and shares land borders with ...

– April 14, 2017) was an American 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 invention of public-key cryptography in cooperation with Whitfield Diffie and Ralph Merkle. Hellman is a longtime contributor to the ...

's at

Stanford University Leland Stanford Junior University, commonly referred to as Stanford University, is a Private university, private research university in Stanford, California, United States. It was founded in 1885 by railroad magnate Leland Stanford (the eighth ...

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,#Mollin06, Mollin 2006, pg. 344 is a special-purpose algorithm for computing discrete logarithms in a finite abelian group whose order i ...

for computing

discrete logarithm In mathematics, for given real numbers a and b, the logarithm \log_b(a) is a number x such that b^x=a. Analogously, in any group G, powers b^k can be defined for all integers k, and the discrete logarithm \log_b(a) is an integer k such that b^k=a ...

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

RSA (cryptosystem) The RSA (Rivest–Shamir–Adleman) cryptosystem is a public-key cryptosystem, one of the oldest widely used for secure data transmission. The initialism "RSA" comes from the surnames of Ron Rivest, Adi Shamir and Leonard Adleman, who publi ...

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. Pohlig died on April 14, 2017, at the age of 64 after fighting gallbladder cancer for a year.

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.

References

1953 births 2017 deaths American electrical engineers MIT Lincoln Laboratory people American computer security academics Engineers from Washington, D.C. {{US-electrical-engineer-stub