Public-key cryptography: Difference between revisions

An asymmetric-key cryptosystem was published in 1976 by [[Whitfield Diffie]] and [[Martin Hellman]], who, influenced by [[Ralph Merkle]]'s work on public-key distribution, disclosed a method of public-key agreement. This method of key exchange, which uses exponentiation in a finite field, came to be known as [[Diffie-Hellman key exchange]]. This was the first published practical method for establishing a shared secret-key over an authenticated (but not private) communications channel without using a prior shared secret. Merkle's public-key-agreement technique became known as [[Ralph Merkle puzzle cryptographic system|Merkle's Puzzles]], and was invented in 1974 and published in 1978.

 

 

Since the 1970s, a large number and variety of encryption, digital signature, key agreement, and other techniques have been developed in the field of public-key cryptography. The [[ElGamal encryption|ElGamal cryptosystem]] (invented by [[Taher ElGamal]]) relies on the (similar, and related) difficulty of the [[discrete logarithm problem]], as does the closely related [[Digital Signature Algorithm|DSA]] developed at [[NSA]] and published by [[NIST]] as a proposed standard. The introduction of [[elliptic curve cryptography]] by [[Neal Koblitz]] and [[Victor S. Miller|Victor Miller]] independently and simultaneously in the mid 1980s has yielded new public-key algorithms based on the [[discrete logarithm]] problem. Although mathematically more complex, elliptic curves provide smaller [[key size]]s and faster operations for equivalent estimated security.