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copied!<p>There are several things going on:</p> <ol> <li><p><a href="http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#getBytes()" rel="nofollow noreferrer"><code>msg.getBytes()</code></a> returns the bytes representing an encoding of the string using the "platform's default charset" (e.g. could be UTF-8 <em>or</em> UTF-16 <em>or</em> ..): <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#getBytes(java.nio.charset.Charset)" rel="nofollow noreferrer">specify the encoding manually</a> to avoid confusion! In any case, see <code>msgBytes.length</code> to get the <em>true</em> plain text length.</p></li> <li><p><a href="http://en.wikipedia.org/wiki/DES" rel="nofollow noreferrer">DES</a>, being a block cypher, will have output padded along a <a href="http://en.wikipedia.org/wiki/Block_size_(cryptography)" rel="nofollow noreferrer">block size</a> boundary - <em>but</em> this will <em>always</em> be larger than the plain text (refer to <code>msgBytes.length</code>) length when using <a href="http://www.ietf.org/rfc/rfc2898.txt" rel="nofollow noreferrer">PKCS#5</a> because the plain text is always padded with [1,8] bytes. To see what the <em>true</em> encrypted size is, see <code>textEncrypted.length</code>.</p></li> <li><p>The encrypted bytes are encoded using base-64 and this process - which is independent of the encryption - inflates the number of bytes required <a href="https://stackoverflow.com/questions/4715415/base64-what-is-the-worst-possible-increase-in-space-usage">by about 33%</a> (as only 6 bits per character/byte are used). The Java base-64 implementation also <a href="http://en.wikipedia.org/wiki/Base64#Padding" rel="nofollow noreferrer">adds padding</a> which is where the trailing "=" character is introduced.</p></li> </ol> <p>As long as you (or someone else with the correct algorithm and cipher key) can retrieve the initial string - by performing the inverse of each step in reverse order, then it works. If a particular step does not have an inverse/reverse operation or cannot be "undone", then something is wrong; but this also means that <em>every step can be individually tested</em>.</p> <hr> <p>To the numbers!</p> <ol> <li><code>msg.getBytes()</code> returns an ASCII/UTF-8 encoded sequence (if it used UTF-16 or another another "wide" encoding then the numbers below would be too large)</li> <li>Therefore, <code>msgBytes.length</code> is 24</li> <li>And since <code>msgBytes.length</code> mod 8 is 0, the plain text is <em>padded</em> with 8 bytes that have the value of 0x08 (per CKCS#5)</li> <li>Thus, <code>textEncrypted.length</code> is 32 (24 data + 8 padding)</li> <li>Due to base-64 encoding, 32 bytes * 1.33 ~ 43 characters</li> <li>And with base-64 padding (<code>=</code>), the final result is 44 characters!</li> </ol>

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