Public Key Infrastructure (PKI)
A secure method for exchanging information within an organization, an industry, a nation or worldwide. A PKI uses the asymmetric encryption method, also known as the "public/private key" method, for encrypting IDs and documents/messages (ie., cryptography). It starts with the certificate authority (CA), which issues digital certificates (digital IDs) that authenticate the identity of people and organizations over a public system such as the Internet. The PKI can also be implemented by an enterprise for internal use to authenticate users that handle sensitive information. In this case, the enterprise is its own CA.
The PKI also establishes the encryption algorithms, levels of security and distribution policy to users. It not only deals with signed certificates for identity authentication, but also with signed messages, which ensures the integrity of the message so the recipient knows it has not been tampered with. The PKI also embraces all the software (browsers, e-mail programs, etc.) that supports the process by examining and validating the certificates and signed messages.