All SSL sessions begin with an exchange of messages called the SSL handshake.

• The handshake allows the server to authenticate itself to the client
• It then allows the client and the server to cooperate in the creation of keys.
• The keys are then used for rapid encryption, decryption, and tamper detection during the session that follows.

The padlock simply represents the fact that:

• Communication to and from the website is encrypted.
• Encryption means that no one else, besides that particular website, can read any of the details you enter there.

Through the established secure channel, the client and the server use the session keys:

• To encrypt and decrypt the data they send to each other
• As well as to validate its integrity.

Digital signatures are the digital version of the traditional, legal signature on a paper document.

As with a legal signature, digital signatures provide the following security capabilities:

• Authentication
• Nonrepudiation

Encryption is a method to exchange information such that it cannot be read or understood until it is changed back into a readable and understandable form.

Message encryption provides two specific security services:

• Confidentiality
• Data integrity