| Diffie-hellman Key Exchange |
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Information AboutDiffie-hellman Key Exchange |
| CATEGORIES ABOUT DIFFIE-HELLMAN KEY EXCHANGE | |
| cryptographic protocols | |
| asymmetric-key cryptosystems | |
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Synonyms of Diffie-Hellman key exchange include:
The scheme was first published publicly by Whitfield Diffie and Martin Hellman in 1976 , although it later emerged that it had been invented a few years earlier within GCHQ , the British signals intelligence agency, by Malcolm J. Williamson but was kept classified. In 2002 , Hellman suggested the algorithm be called Diffie-Hellman-Merkle key exchange in recognition of Ralph Merkle 's contribution to the invention of Public-key Cryptography (Hellman, 2002). Although Diffie-Hellman key agreement itself is an ''anonymous'' (non-''authenticated'') Key-agreement Protocol , it provides the basis for a variety of authenticated protocols, and is used to provide Perfect Forward Secrecy in TLS 's ephemeral modes. HISTORY OF THE PROTOCOL Diffie-Hellman key agreement was invented in 1976 during a collaboration between Whitfield Diffie and Martin Hellman and was the first practical method for establishing a Shared Secret over an unprotected communications channel. Ralph Merkle 's work on public key distribution was an influence. John Gill suggested application of the Discrete Logarithm problem. It had been discovered by Malcolm Williamson of GCHQ in the UK some years previously, but GCHQ chose not make it public until 1997 , by which time it had no influence on research in Academia . The method was followed shortly afterwards by RSA , another implementation of public key cryptography using Asymmetric Algorithms . In 2002 , Martin Hellman wrote: The system...has since become known as Diffie-Hellman key exchange. While that system was first described in a paper by Diffie and me, it is a public key distribution system, a concept developed by Merkle, and hence should be called 'Diffie-Hellman-Merkle key exchange' if names are to be associated with it. I hope this small pulpit might help in that endeavor to recognize Merkle's equal contribution to the invention of public key cryptography. {Link without Title} , now expired, describes the algorithm and credits Hellman, Diffie, and Merkle as inventors. DESCRIPTION The simplest, and original, implementation of the protocol uses the Multiplicative Group of integers modulo ''p'', where ''p'' is Prime and ''g'' is Primitive Root mod ''p''. Modulo (or mod) means that the integers between 0 and ''p'' − 1 are used with normal addition, subtraction, multiplication, and exponentiation, except that after each operation the result keeps only the Remainder after dividing by ''p''. Here is an example of the protocol:
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