What are Digital Certificate and Private Key?
Digital certificate is a file that contains the user’s information, signed by the Certification Authority (CA). It also contains the public key of the user which is made publicly available to all the other users. The private key which corresponds to the public key in the certificate is a secret key that is kept by the user, either in the form of a smart card, USB token, or stored on the local hard disk. The private key and the public key are very large numbers that are generated with special mathematical property. Specifically, the private key can be used to digitally “sign” a document or email in which the signature can be verified by the public key (or the certificate containing the public key). For encryption, other user can encrypt a digital document or email to the user by using the user’s public key. In this case, the encrypted content can only be decrypted by the user’s corresponding private key. These two operations are the foundation of public key cryptography technology.
