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parison to standard modes. As of this writing, there are three free, publicly available<br />

implementations of CCM mode:<br />

• The reference implementation: http://hifn.com/support/ccm.htm<br />

• The implementation from Secure Software: http://www.securesoftware.com/ccm.php<br />

• The implementation from Brian Gladman: http://fp.gladman.plus.com/AES/ccm.zip<br />

See Also<br />

• CCM reference implementation: http://hifn.com/support/ccm.htm<br />

• CCM implementation from Secure Software: http://www.securesoftware.com/<br />

ccm.php<br />

• CCM implementation from Brian Gladman: http://fp.gladman.plus.com/AES/<br />

ccm.zip<br />

• CWC home page: http://www.zork.org/cwc/<br />

• OCB home page: http://www.cs.ucdavis.edu/~rogaway/ocb/<br />

• Recipes 4.9, 4.11, 5.5-5.10, 5.14, 5.16<br />

5.5 Using a Raw Block Cipher<br />

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

You’re trying to make one of our implementations for other block cipher modes<br />

work. They all use raw encryption operations as a foundation, and you would like to<br />

understand how to plug in third-party implementations.<br />

Solution<br />

Raw operations on block ciphers consist of three operations: key setup, encryption of<br />

a block, and decryption of a block. In other recipes, we provide three macros that<br />

you need to implement to use our code. In the discussion for this recipe, we’ll look at<br />

several desirable bindings for these macros.<br />

Discussion<br />

Do not use raw encryption operations in your own designs! Such operations<br />

should only be used as a fundamental building block by skilled<br />

cryptographers.<br />

Raw block ciphers operate on fixed-size chunks of data. That size is called the block<br />

size. The input and output are of this same fixed length. A block cipher also requires<br />

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

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

Using a Raw Block Cipher | 171

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