Technology used for securing digital documents.

Public-key technology uses key pairs to provide its protection. Each participant receives an individual key pair consisting of a public key and a private key. These keys have the following characteristics:

• The keys are pairs; they belong together.
• You cannot obtain the private key from the public key.
• As the name suggests, the public key is to be made public. The owner of the keys distributes the public key as necessary. For example, a recipient of a digitally signed document needs to have knowledge of the signer‘s public key in order to verify the digital signature. In addition, to send an encrypted document, the sender needs to know the recipient's public key.
• The private key is to be kept secret. The owner of the keys uses the private key to generate his or her digital signature and to decrypt messages encrypted with his or her public-key. Therefore, the owner of the keys needs to make sure that no unauthorized person has access to his or her private key.