Asymmetric encryption overcomes this problem by using two cryptographically related keys, a key pair - a public key and a private key. The private key is kept secret in your system and the public key is made available freely to anyone who might want to exchange messages with you. Any message, be it text, documents or binary files that are encrypted using the public key can be decrypted using the corresponding private key only. Similarly anything that is encrypted using the private key can be decrypted using the corresponding public key. Typically public keys are made available to everyone by using Digital Certificates. The certificates are issued by a Certificate Authority (CA), which identifies a server or user and usually contains information such as the CA who issued it, the organization's name, email address of the user and country and the public key of the user. When a secure encrypted communication is required between a client and a server, a query is sent over to the other party for the certificate and the public key can be extracted from it.