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130 lines
9.2 KiB
HTML
130 lines
9.2 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
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"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh-CN" lang="zh-CN">
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<head>
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<meta http-equiv="content-type" content="text/html; charset=utf-8" />
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<title>VeraCrypt - 为偏执者提供强大安全保障的免费开源磁盘加密工具</title>
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<meta name="description" content="VeraCrypt是一款适用于Windows、Mac OS X和Linux的免费开源磁盘加密软件。如果攻击者迫使您透露密码,VeraCrypt提供似是而非的否认能力。与文件加密不同,VeraCrypt执行的数据加密是实时(即时)、自动、透明的,只需要很少的内存,并且不涉及临时未加密文件。"/>
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<meta name="keywords" content="加密, 安全"/>
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<link href="styles.css" rel="stylesheet" type="text/css" />
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</head>
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<body>
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<div>
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<a href="Documentation.html"><img src="VeraCrypt128x128.png" alt="VeraCrypt"/></a>
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</div>
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<div id="menu">
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<ul>
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<li><a href="Home.html">主页</a></li>
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<li><a href="Code.html">源代码</a></li>
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<li><a href="Downloads.html">下载</a></li>
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<li><a class="active" href="Documentation.html">文档</a></li>
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<li><a href="Donation.html">捐赠</a></li>
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<li><a href="https://sourceforge.net/p/veracrypt/discussion/" target="_blank">论坛</a></li>
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</ul>
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</div>
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<div>
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<p>
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<a href="Documentation.html">文档</a>
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<img src="arrow_right.gif" alt=">>" style="margin-top: 5px">
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<a href="Technical%20Details.html">技术细节</a>
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<img src="arrow_right.gif" alt=">>" style="margin-top: 5px">
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<a href="Modes%20of%20Operation.html">操作模式</a>
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</p></div>
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<div class="wikidoc">
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<h1>操作模式</h1>
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<div style="text-align:left; margin-top:19px; margin-bottom:19px; padding-top:0px; padding-bottom:0px">
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<br style="text-align:left">
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VeraCrypt用于加密分区、驱动器和虚拟卷的操作模式是XTS。
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<br style="text-align:left">
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<br style="text-align:left">
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XTS模式实际上是XEX模式 <a href="http://www.cs.ucdavis.edu/%7Erogaway/papers/offsets.pdf">
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[12]</a>,它由Phillip Rogaway在2003年设计,有一个小的修改(XEX模式将单个密钥用于两个不同的目的,而XTS模式使用两个独立的密钥)。<br style="text-align:left">
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<br style="text-align:left">
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2010年,XTS模式被美国国家标准与技术研究院(NIST)批准用于保护存储设备上数据的机密性 [24]。2007年,它也被电气和电子工程师协会(IEEE)批准用于面向块的存储设备上数据的加密保护(IEEE 1619)。</div>
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<div style="text-align:left; margin-top:19px; margin-bottom:19px; padding-top:0px; padding-bottom:0px">
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</div>
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<h2 style="text-align:left; margin-top:19px; margin-bottom:19px; padding-top:0px; padding-bottom:0px">
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<strong style="text-align:left">XTS模式的描述</strong>:</h2>
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<div style="text-align:left; margin-top:19px; margin-bottom:19px; padding-top:0px; padding-bottom:0px">
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<em style="text-align:left">C<sub style="text-align:left; font-size:85%">i</sub></em> =
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<em style="text-align:left">E</em><sub style="text-align:left; font-size:85%"><em style="text-align:left">K</em>1</sub>(<em style="text-align:left">P<sub style="text-align:left; font-size:85%">i</sub></em> ^ (<em style="text-align:left">E</em><sub style="text-align:left; font-size:85%"><em style="text-align:left">K</em>2</sub>(<em style="text-align:left">n</em>)
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<img src="gf2_mul.gif" alt="" width="10" height="10">
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<em style="text-align:left">a<sup style="text-align:left; font-size:85%">i</sup></em>)) ^ (<em style="text-align:left">E</em><sub style="text-align:left; font-size:85%"><em style="text-align:left">K</em>2</sub>(<em style="text-align:left">n</em>)
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<img src="gf2_mul.gif" alt="" width="10" height="10"><em style="text-align:left"> a<sup style="text-align:left; font-size:85%">i</sup></em>)</div>
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<div style="text-align:left; margin-top:19px; margin-bottom:19px; padding-top:0px; padding-bottom:0px">
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其中:</div>
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<table style="border-collapse:separate; border-spacing:0px; width:608px; text-align:left; font-size:11px; line-height:13px; font-family:Verdana,Arial,Helvetica,sans-serif; border:0px outset #999">
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<tbody style="text-align:left">
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<tr style="text-align:left">
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<td style="vertical-align:top; color:#000000; text-align:left; font-size:11px; line-height:13px; font-family:Verdana,Arial,Helvetica,sans-serif; padding:0px">
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<sup style="text-align:left; font-size:85%"> <img src="gf2_mul.gif" alt="" width="10" height="10"></sup></td>
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<td style="vertical-align:top; color:#000000; text-align:left; font-size:11px; line-height:13px; font-family:Verdana,Arial,Helvetica,sans-serif; padding:0px">
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表示在二进制域GF(2)上,两个多项式模 <em style="text-align:left">
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x</em><sup style="text-align:left; font-size:85%">128</sup>+<em style="text-align:left">x</em><sup style="text-align:left; font-size:85%">7</sup>+<em style="text-align:left">x</em><sup style="text-align:left; font-size:85%">2</sup>+<em style="text-align:left">x</em>+1 的乘法</td>
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</tr>
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<tr style="text-align:left">
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<td style="width:30px; vertical-align:top; color:#000000; text-align:left; font-size:11px; line-height:13px; font-family:Verdana,Arial,Helvetica,sans-serif; padding:0px">
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<br style="text-align:left">
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<em style="text-align:left">K</em>1</td>
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<td style="width:578px; vertical-align:top; color:#000000; text-align:left; font-size:11px; line-height:13px; font-family:Verdana,Arial,Helvetica,sans-serif; padding:0px">
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<br style="text-align:left">
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是加密密钥(对于每个支持的密码算法,如AES、Serpent和Twofish,均为256位)</td>
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</tr>
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<tr style="text-align:left">
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<td style="vertical-align:top; color:#000000; text-align:left; font-size:11px; line-height:13px; font-family:Verdana,Arial,Helvetica,sans-serif; padding:0px">
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<br style="text-align:left">
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<em style="text-align:left">K</em>2</td>
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<td style="vertical-align:top; color:#000000; text-align:left; font-size:11px; line-height:13px; font-family:Verdana,Arial,Helvetica,sans-serif; padding:0px">
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<br style="text-align:left">
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是辅助密钥(对于每个支持的密码算法,如AES、Serpent和Twofish,均为256位)</td>
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</tr>
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<tr style="text-align:left">
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<td style="vertical-align:top; color:#000000; text-align:left; font-size:11px; line-height:13px; font-family:Verdana,Arial,Helvetica,sans-serif; padding:0px">
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<br style="text-align:left">
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<em style="text-align:left">i</em></td>
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<td style="vertical-align:top; color:#000000; text-align:left; font-size:11px; line-height:13px; font-family:Verdana,Arial,Helvetica,sans-serif; padding:0px">
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<br style="text-align:left">
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是数据单元内的密码块索引; 对于数据单元内的第一个密码块,
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<em style="text-align:left">i</em> = 0</td>
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</tr>
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<tr style="text-align:left">
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<td style="vertical-align:top; color:#000000; text-align:left; font-size:11px; line-height:13px; font-family:Verdana,Arial,Helvetica,sans-serif; padding:0px">
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<br style="text-align:left">
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<em style="text-align:left">n</em></td>
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<td style="vertical-align:top; color:#000000; text-align:left; font-size:11px; line-height:13px; font-family:Verdana,Arial,Helvetica,sans-serif; padding:0px">
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<br style="text-align:left">
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是在 <em style="text-align:left">K</em>1 范围内的数据单元索引; 对于第一个数据单元,
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<em style="text-align:left">n</em> = 0</td>
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</tr>
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<tr style="text-align:left">
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<td style="vertical-align:top; color:#000000; text-align:left; font-size:11px; line-height:13px; font-family:Verdana,Arial,Helvetica,sans-serif; padding:0px">
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<br style="text-align:left">
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<em style="text-align:left">a</em></td>
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<td style="vertical-align:top; color:#000000; text-align:left; font-size:11px; line-height:13px; font-family:Verdana,Arial,Helvetica,sans-serif; padding:0px">
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<br style="text-align:left">
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是伽罗瓦域 (2<sup style="text-align:left; font-size:85%">128</sup>) 中对应于多项式
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<em style="text-align:left">x</em>(即2)的一个本原元</td>
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</tr>
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<tr style="text-align:left">
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<td colspan="2" style="vertical-align:top; color:#000000; text-align:left; font-size:11px; line-height:13px; font-family:Verdana,Arial,Helvetica,sans-serif; padding:0px">
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<br style="text-align:left">
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<span style="text-align:left; font-size:10px; line-height:12px">注意:其余符号的定义见
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<a href="Notation.html" style="text-align:left; color:#0080c0; text-decoration:none.html">
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符号说明</a> 部分。 </span></td>
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</tr>
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</tbody>
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</table>
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<div style="text-align:left; margin-top:19px; margin-bottom:19px; padding-top:0px; padding-bottom:0px">
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<br style="text-align:left">
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每个数据单元的大小始终为512字节(与扇区大小无关)。</div>
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<div style="text-align:left; margin-top:19px; margin-bottom:19px; padding-top:0px; padding-bottom:0px">
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有关XTS模式的更多信息,请参阅例如 <a href="http://www.cs.ucdavis.edu/%7Erogaway/papers/offsets.pdf" style="text-align:left; color:#0080c0; text-decoration:none">
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[12]</a> 和 <a href="http://csrc.nist.gov/publications/nistpubs/800-38E/nist-sp-800-38E.pdf" style="text-align:left; color:#0080c0; text-decoration:none">
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[24]</a>。</div>
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<div style="text-align:left; margin-top:19px; margin-bottom:19px; padding-top:0px; padding-bottom:0px">
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<a href="Header%20Key%20Derivation.html" style="text-align:left; color:#0080c0; text-decoration:none; font-weight:bold.html">下一部分 >></a></div>
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