Information, Computer and Network Security Terms Glossary and Dictionary

Public-Key or Asymmetric Cryptography

Public Key Cryptography provides a way for computer users to securely exchange information. The Public-Key Cryptography Standards (PKCS) are specifications produced by RSA Laboratories in cooperation with secure systems developers worldwide. The PKCS documents have been widely implemented and contributions from the PKCS series have become part of many formal and de facto standards, including ANSI X9 documents, PKIX, SET, S/MIME, and SSL. Public-key encryption is also called asymmetric encryption, which is based on the mathematic scheme developed by Diffie and Hellman.

The public key cryptography process allows any person to encrypt a message and send it to another person without prior key exchange. It is unnecessary for these two persons to know each other or belong to the same organization. In the Public-key encryption process, there are two keys required for person who need to exchange sensitive data document over Internet: a public key and a private key. Each public key is published, and the corresponding private key is kept secret. Data encrypted with your public key can be decrypted only with your private key. In general, to send encrypted data to someone, you encrypt the data with that person's public key, and the person receiving the encrypted data decrypts it with the corresponding private key.

The reverse of the scheme also works: data encrypted with your private key can be decrypted only with your public key. This is not a useful way to encrypt sensitive data since that anyone can obtain the public key to decrypt the information. However, it can be applied to the situation where you can use your private key to sign data with your digital signature, which is an essential requirement for electronic commerce of cryptography.Public Key Infrastructure (PKI) is a system based on the above basic concepts to provide public key creation and management for users to encrypt data and exchange keys effectively.

Related Terms

Private Key, PKI, Encryption, Decryption, ANSI X9, PKIX, S/MIME, and SSL.

Reference Links

http://www.rsasecurity.com/rsalabs/node.asp?id=2124: Public-Key Cryptography Standards