A digital certificate is just an electronic document with the owners personal information and a checksum generated by the authority who published the certificate. The checksum which is generated to certify that the document not has been changed shall always be possible to verify with the publishing authority. Just like a passport or a drivers license. When a certificate is distributed it is also common to attach a encryption key to the certificate that can be used to encrypt messages to or decrypt messages from the owner.

A certificate can be used to verify the identity of a person, a machine or an application so it can fulfill a broad range of authorization functions.

To solve the distribution problems with encryption keys the common standard is to use two keys, one private held by the owner and one public which can freely be distributed. The private key is used by the owner to encrypt information to guarantee it has origin from him 8when possible to decrypt with his public key. It is also used to decrypt information received that has been encrypted by a public key, this way the information is only visible for the private key owner. To achieve full security the keys is used in two pairs where each of the parts have his own private and the opponents public key.

This means that for example an agreement that has been encrypted by the owners private key can be red by anyone but the origin is ensured to be the owner. A message that is encrypted with a public key can only be red by the owner of the matching private key but has no guarantee of who sent it. By using the keys in combination in an intelligent way full security can be reached.

802.1x
802.1x is a standard that is used to authenticate equipment that are about to connect to a wireless or wired network. When the connection is initiated only the 802.1x protocol is permitted and is used to verify that the user and machine is authenticated by an overlaying method as for example Kerberos. In the protocol is also included methods to report the result of the authentication to the access point.