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What is a Public Key Infrastructure?

Ryan Russell
Ryan Russell

The public key infrastructure allows users on unsecured public networks like the Internet to transmit data in a secure and private fashion. This is accomplished through the use of public and private cryptographic keys acquired and shared through a trusted server. The public key infrastructure comes equipped with a digital certificate that is able to identify a particular individual or company and issue certificates as needed. This infrastructure also allows for the revocation of the certificates, as well as secured storage through a directory system.

Public key cryptography is used in conjunction with public key infrastructure to authenticate the sender of a message and to encrypt the message as well. More typical cryptography techniques create and issue hidden keys that are not always well-secured and, thus, can be intercepted and easily decrypted. This is why public key cryptography is the most commonly-used method of authentication and encryption on the Internet.

Man holding computer
Man holding computer

The public key infrastructure comes with a certificate authority that creates and checks digital certificates. A digital certificate contains the public key itself or details about the public key. The infrastructure also comes with a registration authority that functions as the gatekeeper for the certificate authority before a digital certificate is created for a user. Public keys are held in multiple directories built into the infrastructure. A certificate management system is also in place to keep track of all the certificates issued and revoked.

Public key cryptography works by creating a public and private key using the certificate authority. The private key is issued to the requester and the public key is made freely accessible in an open directory. The private key is secured throughout the whole process and is never given to additional users. The private key is used to decrypt information that has been encrypted with the public key by another user. The private key can be used to encrypt digital certificates as well as standard messages.

The public key infrastructure is always being improved by various vendors who use it for their own networks and applications. The infrastructure is being employed for many additional uses like document verification and encryption. The telecommunications industry uses electronic keys called mobile signatures that often use the public key system to issue encrypted certificates and transmit secured data among mobile devices. In addition, the public key infrastructure is often used for user authentication systems as a way of securing the user’s personal data and protecting the session with the server.

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