Secure Sockets Layer or SSL is a protocol that provides security for communications between a client and a Server. SSL accomplishes secure communication by implementing data encryption and certificate-based authentication.

SSL uses a cryptographic system that uses two keys to encrypt data, a public key known to everyone and a private or secret key known to the sender. The sender uses the private key to sign a file. A recipient of the signed file can verify the signature only by the corresponding public key. However, a public and private keys are not enough to truly verify a signature. The additional element that is required for the signing and verification processes to work is called a Certificate.