9 
Message Delivery
User
Encryption Performed
User
Decryption Performed
Unencrypted Message
Unencrypted Message
 
Figure 10 – Symmetric Cryptography 
 
 
In Figure 10, the confidentiality provided to the message is done via a single key.  Because the same 
key is used for encryption and decryption, this process is known as symmetric cryptography.  
Symmetric cryptography commonly has two attributes associated with it: 
 
•  It performs well – it is fast and easy to implement 
•  It has a key distribution problem – how do you get the symmetric key to everyone that needs 
it in a secure way? 
 
Asymmetric cryptography is also available and functions very different than symmetric cryptography.  
It has two keys – one Public and one Private.  The private key is not shared with anyone. The Public 
key is like a public telephone number.  You can share it with everyone.  Let’s look at Figure 11 – 
Asymmetric Cryptography.