A public key certificate is a cryptographic document utilized by computers to verify the identity of a named party when communicating over the Internet or other network. These certificates typically consist of a digital signature of a certifying authority, a sender’s public key, and other identifying information to verify a sender’s identity to a recipient. Public key certificates are an established part of secured network and Internet communications.
A public key certificate falls within the realm of computerized cryptography, which involves the conversion of data into a secure format that renders it unreadable to others without the proper means of rendering it decipherable. A vital component of a public key certificate is the public key algorithm, a kind of mathematical code. The public key algorithm enables encryption of data exchanged between computers while providing for secure remote access to a user through interaction with a private key. Public key certificates' encrypted format helps to provide privacy in communications, especially in sensitive e-mail correspondence and electronic commerce.
Public key certificates consist of multiple components, such as textual and numerical naming of the recipient of the document, the recipient’s digital signature, and the certificate authority that rendered the public key. Important data like the date issued and expiration of the certificate, the encryption algorithm and an identifying code to show the authenticity of the certificate is included. Certificates are issued for a limited time period, must be renewed once or several times a year, and can be revoked if circumstances warrant.
A certification authority is responsible for issuing public key certificates, and can be private, commercial, or governmental in nature. Private and commercial authorities typically charge for the issuance of digital certifications, which are accepted by most Internet-based web-browsing applications. These entities take steps to protect against the manipulation of certificates and help to maintain the confidentiality of sensitive data held within the certificate. Although it is ultimately up to the user visiting a website to determine communications safety, certification authorities are obliged and trusted to verify the identity of those to whom they issue public key certificates.
The most common use of a public key certificate is for interaction with Internet-based websites. A recipient’s computer validates a sender’s website credentials, so the user has authentic interaction with the subject website and a level of security. This type of certificate–based authentication plays an important part in secure communications and electronic commerce.