Key-based Algorithms

A key-based algorithm uses an encryption key to encrypt the message. This means that the encrypted message is generated using not only the message, but also using a 'key'.

Figure 1. Key-based encryption

The receiver can then use a decryption key to decrypt the message. Again, this means that the decryption algorithm doesn't rely only on the encrypted message. It also needs a 'key':

Figure 2. Key-based decryption