Summary

The major point of this chapter is how the Cryptography Application Block not only makes it easier to perform cryptographic tasks that would otherwise take a lot of skill and effort, but also how the block performs these functions according to the best practices documented in Chapters 8 and 9 of the book Writing Secure Code, Second Edition, by Michael Howard and David C. LeBlanc. After the basic concepts of cryptography and the Microsoft .NET Framework were explored, the chapter continued with a detailed examination of the design of the Cryptography Application Block and how this design makes it easy for you to accomplish the most common cryptography tasks without incurring significant performance degradation. This chapter examined the design and functions of the Cryptographer, the DpapiSymmetricCryptoProvider, the SymmetricAlgorithmProvider, the HashAlgorithmProvider, and the KeyedHashAlgorithmProvider and the use of these providers' cryptographic utility classes that reside in the Common namespace.

The chapter concluded with demonstrations of how to configure the different providers with the Enterprise Library Configuration Tool and how to code against these providers. It showed how to configure the SymmetricAlgorithmProviders and how to code an application to use these providers for encrypting and decrypting data, and how the symmetric key can be protected by using the related cryptographic capabilities of Enterprise Library's Configuration Application Block. This chapter also reviewed how to configure hash providers and code against these providers to create and compare hashes. Throughout the chapter, emphasis was placed on the fact that, by using the Cryptography Application Block, very little code needs to be written to adhere to the best practices for cryptography.