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Problem - Kevin Tafuro

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Chapter 5 CHAPTER 5<br />

Symmetric Encryption<br />

This chapter discusses the basics of symmetric encryption algorithms. Message integrity<br />

checking and hash functions are covered in Chapter 6. The use of cryptography<br />

on a network is discussed in Chapter 9.<br />

Many of the recipes in this chapter are too low-level for general-purpose<br />

use. We recommend that you first try to find what you need in<br />

Chapter 9 before resorting to building solutions yourself using the recipes<br />

in this chapter. If you do use these recipes, please be careful, read<br />

all of our warnings, and do consider using the higher-level constructs<br />

we suggest.<br />

5.1 Deciding Whether to Use Multiple<br />

Encryption Algorithms<br />

<strong>Problem</strong><br />

You need to figure out whether to support multiple encryption algorithms in your<br />

system.<br />

Solution<br />

There is no right answer. It depends on your needs, as we discuss in the following<br />

section.<br />

Discussion<br />

Clearly, if you need to support multiple encryption algorithms for standards compliance<br />

or legacy support, you should do so. Beyond that, there are two schools of<br />

thought. The first school of thought recommends that you support multiple algorithms<br />

to allow users to pick their favorite. The other benefit of this approach is that<br />

This is the Title of the Book, eMatter Edition<br />

Copyright © 2007 O’Reilly & Associates, Inc. All rights reserved.<br />

155

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