 - Asymmetric cryptography is cryptography in which a pair of keys is used to encrypt and decrypt a message so that it arrives securely. Initially, a network user requests a public and private key pair. A user who wants to send an encrypted message can get the intended recipient's public key from a public administrator. When the recipient gets the message, they decrypt it with their private key, which no one else should have access to. This process is known as a public key infrastructure. Witfield Diffie & Martin Hellman, then researchers at Stanford University, first publicly proposed asymmetric encryption in their 1977 paper, New Directions In Cryptography. (The concept had been independently and privately proposed by James Ellis several years before when he was working for the British Government Communications Headquarters.) An asymmetric algorithm, as outlined in the Diffie-Hellman paper, is a trap door one-way function. A one-way function is easy to perform in one direction, but difficult or impossible to reverse. A trap door one-way function, is one that is easy to reverse if you have information about the trap door, but difficult or impossible to reverse if you lack that information. In symmetric cryptography, the same key is used for both encryption and decryption. This approach is simpler but less secure since the key must be communicated to and known at both sender and receiver locations.
| CONTRIBUTORS: |
Chris Ruffley |
| LAST UPDATED: |
04 Jun 2007
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