Diffie–Hellman key exchange

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Diffie–Hellman (DH) key exchange is a mathematical method of securely generating a symmetric cryptographic key over a public channel. It is named after Whitfield Diffie and Martin Hellman who published it in 1976. DH is one of the earliest practical examples of key exchange implemented within the field of cryptography. Traditionally, secure encrypted communication between two parties required that they first exchange keys by some secure physical means, such as paper key lists transported by a trusted courier. By contrast, the Diffie–Hellman key exchange method allows two parties that have no prior knowledge of each other to jointly establish a shared secret key over an insecure channel. This key can then be used to encrypt subsequent communications using a symmetric-key cipher. The scheme was published by Whitfield Diffie and Martin Hellman in 1976 and named as one of Ralph Merkle's original public key protocols in 1978. The method was followed shortly after by the RSA cryptosystem, an...

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