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Java安全－－密码

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<td width="90%"><font size="4" face="Verdana, Arial, Helvetica"><b>算法、类和方法</b></font></td><td width="200" align="right"><font size="1" face="Verdana, Arial, Helvetica"><nobr>   第 5 页（共7 页）</nobr></font></td>
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<p>JDK 1.4 支持下列私钥算法：</p>
<ul>
<li>
<b>DES。</b>DES（数据加密标准）是由 IBM 于上世纪 70 年代发明的，美国政府将其采纳为标准。它是一种 56 位分组密码。<br>
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</li>
<li>
<b>TripleDES。</b>该算法被用来解决使用 DES 技术的 56 位时密钥日益减弱的强度，其方法是：使用两个密钥对明文运行 DES 算法三次，从而得到 112 位有效密钥强度。TripleDES 有时称为 DESede（表示加密、解密和加密这三个阶段）。<br>
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</li>
<li>
<b>AES。</b>AES（高级加密标准）取代 DES 成为美国标准。它是由 Joan Daemen 和 Vincent Rijmen 发明的，也被称为 Rinjdael 算法。它是 128 位分组密码，密钥长度为 128 位、192 位或 256 位。<br>
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</li>
<li>
<b>RC2、</b><b>RC4、</b>和 <b>RC5。</b>这些算法来自领先的加密安全性公司 RSA Security。<br>
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</li>
<li>
<b>Blowfish。</b>这种算法是由 Bruce Schneier 开发的，它是一种具有从 32 位到 448 位（都是 8 的整数倍）可变密钥长度的分组密码，被设计用于在软件中有效实现微处理器。<br>
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</li>
<li>
<b>PBE。</b>PBE（基于密码的加密）可以与多种消息摘要和私钥算法结合使用。</li>
</ul>
<p>
<code>Cipher</code> 类使用由 <code>KeyGenerator</code> 类产生的密钥操作私钥算法。<a href="j-sec1-4-6.html">私钥密码术代码示例</a>中使用了下列方法：</p>
<ul>
<li>
<code>KeyGenerator.getInstance("DES")</code>、<code>.init(56)</code> 和 <code>.generateKey()</code>：生成密钥。<br>
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</li>
<li>
<code>Cipher.getInstance("DES/ECB/PKCS5Padding")</code>：创建 <code>Cipher</code> 对象（确定算法、方式和填充）。<br>
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</li>
<li>
<code>.init(Cipher.ENCRYPT_MODE, key)</code>：初始化 <code>Cipher</code> 对象。<br>
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</li>
<li>
<code>.doFinal(plainText)</code>：用明文字符串计算密文。<br>
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</li>
<li>
<code>.init(Cipher.DECRYPT_MODE, key)</code>：解密密文。<br>
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</li>
<li>
<code>.doFinal(cipherText)</code>：计算密文。</li>
</ul>
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