Cisco Cisco Web Security Appliance S360 User Guide

To understand how encryption and decryption works, you need to understand a 
little bit about cryptographic encoding techniques. 

 describes some 

terms used in cryptography that are discussed in this chapter. 

Certificate authority

An entity which issues digital certificates for use by 
other parties. 

Certificate authorities are sometimes referred to as 
trusted third parties. Certificate authorities are 
typically commercial companies that charge for their 
services. However, some institutions and governments 
have their own certificate authorities, and some offer 
their services for free.

Cipher

An algorithm used for encoding and decoding text to 
make it unreadable to any system without the 
appropriate key. 

Ciphers work with keys to encode or decode text. 

Ciphertext

Encoded text after a cipher has been applied to it.

Digital certificate

An electronic document that identifies and describes 
an organization that has been verified and signed by a 
trusted organization called a certificate authority. 

A digital certificate is similar in concept to an 
“identification card.” SSL uses certificates to 
authenticate servers.

For more information about digital certificates, see 

Digital signature

A checksum that verifies that a message was created 
by the stated author and was not altered since its 
creation.

Key

A numeric parameter used by a cipher to encode or 
decode text.