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<h1>Custom Encryption Adapters</h1>
<p>db4o still provides a solution for high-security encryption by allowing any user to choose his own encryption mechanism that he thinks he needs. The db4o file IO mechanism is pluggable and any fixed-length encryption mechanism can be added. All that needs to be done is to write an IoAdapter plugin for db4o file IO.</p>
<p>This is a lot easier than it sounds. Simply:</p>
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<li>take the sources of com.db4o.io.RandomAccessFileAdapter as an example <br></li>
<li>write your own IoAdapter implementation that delegates raw file access to another adapter using the GoF decorator pattern. <br></li>
<li>Implement the #read() and #write() methods to encrypt and decrypt when bytes are being exchanged with the file <br></li>
<li>plug your adapter into db4o with the following method:
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<p><code>.NET: Db4o.Configure().Io(new MyEncryptionAdapter()); </code></p>
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<p>However, you'll have to keep in mind that db4o will write partial updates. For example, it may write a full object and then only modify one field entry later on. Therefore it is not sufficient to en-/decrypt each access in isolation. You'll rather have to make up a tiling structure that defines the data chunks that have to be en-/decrypted together.</p><p>A community project containing an XTEA encryption IoAdapter implementation can be found here:</p><p><a href="http://developer.db4o.com/ProjectSpaces/view.aspx/XTEA">http://developer.db4o.com/ProjectSpaces/view.aspx/XTEA</a></p>
<p>Another method to inject encryption capabilities into db4o for instances of specific classes only is to implement and configure an en-/decrypting translator.</p></div>
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This revision (9) was last Modified 2007-03-19T11:16:24 by Tetyana.
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