## public-key cryptography

## Public-Key Cryptography Standards

(PKCS) A set of standards for public-key cryptography, developed by RSA Data Security, Inc. in cooperation with an informal consortium, originally including Apple, Microsoft, DEC, Lotus, Sun and MIT. The PKCS have been cited by the OSI Implementers' Workshop (OIW) as a method for implementation of OSI standards.

PKCS includes both algorithm-specific and algorithm-independent implementation standards. Many algorithms are supported, including RSA and Diffie-Hellman key exchange, however, only the latter two are specifically detailed. PKCS also defines an algorithm-independent syntax for digital signatures, digital envelopes, and extended digital certificates; this enables someone implementing any cryptographic algorithm whatsoever to conform to a standard syntax, and thus achieve interoperability.

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Last updated: 1999-02-16

## public-key encryption

(PKE, Or "public-key cryptography") An encryption scheme, introduced by Diffie and Hellman in 1976, where each person gets a pair of keys, called the public key and the private key. Each person's public key is published while the private key is kept secret. Messages are encrypted using the intended recipient's public key and can only be decrypted using his private key. This is often used in conjunction with a digital signature.

The need for sender and receiver to share secret information (keys) via some secure channel is eliminated: all communications involve only public keys, and no private key is ever transmitted or shared.

Public-key encryption can be used for authentication, confidentiality, integrity and non-repudiation.

RSA encryption is an example of a public-key cryptosystem.

See also knapsack problem.

Last updated: 1995-03-27

## Public Key Infrastructure

<*cryptography, communications*>

(PKI) A system of public key encryption using digital certificates from Certificate Authorities and other registration authorities that verify and authenticate the validity of each party involved in an electronic transaction.

PKIs are currently evolving and there is no single PKI nor even a single agreed-upon standard for setting up a PKI. However, nearly everyone agrees that reliable PKIs are necessary before electronic commerce can become widespread.

Last updated: 1999-11-30

### Nearby terms:

public domain software ♦ **public-key cryptography** ♦ Public-Key Cryptography Standards

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