While working on distributed applications, it is very important to keep information secure, in particular, in the case of eCommerce applications, where user data, such as your personal and credit card-related information, is collected and transmitted over the internet. Cryptography enables us to encrypt and decrypt plain text. To understand it in simple terms, let's suppose that there is plain text in our application that can be transformed by adding a static value to each character in the text, thereby rendering it non-readable. This process is called encryption. Conversely, decryption is the process of transforming this unreadable text back into readable text. 

When you encrypt text, it looks like random bytes, and is called cipher-text. 

After reading this chapter, you will be able to understand how to encrypt and decrypt text, the different algorithms that are available to perform these encrypt and decrypt operations, and the options that .NET Framework affords us in terms of their application to actual projects.

The following topics will be covered in this chapter:

• Cryptography
• Symmetric encryption
• Asymmetric encryption
• Digital signatures
• Hash values