mirror of
https://github.com/veracrypt/VeraCrypt.git
synced 2025-11-11 02:58:02 -06:00
4e112df0d2
* Documentation: Remove XHTML spec and fix errors None of the docs follow the XHTML specification, which means that programs that expect this (such as Gnome Web) as it is advertised as such, will completely fail to parse it as it is incorrect syntax. So it is removed. * Remove .chm files
130 lines
9.2 KiB
HTML
130 lines
9.2 KiB
HTML
<!DOCTYPE html>
|
|
<html lang="en">
|
|
<head>
|
|
<meta http-equiv="content-type" content="text/html; charset=utf-8" />
|
|
<title>VeraCrypt - Free Open source disk encryption with strong security for the Paranoid</title>
|
|
<meta name="description" content="VeraCrypt is free open-source disk encryption software for Windows, Mac OS X and Linux. In case an attacker forces you to reveal the password, VeraCrypt provides plausible deniability. In contrast to file encryption, data encryption performed by VeraCrypt is real-time (on-the-fly), automatic, transparent, needs very little memory, and does not involve temporary unencrypted files."/>
|
|
<meta name="keywords" content="encryption, security"/>
|
|
<link href="styles.css" rel="stylesheet" type="text/css" />
|
|
</head>
|
|
<body>
|
|
|
|
<div>
|
|
<a href="Documentation.html"><img src="VeraCrypt128x128.png" alt="VeraCrypt"/></a>
|
|
</div>
|
|
|
|
<div id="menu">
|
|
<ul>
|
|
<li><a href="Home.html">Home</a></li>
|
|
<li><a href="Code.html">Source Code</a></li>
|
|
<li><a href="Downloads.html">Downloads</a></li>
|
|
<li><a class="active" href="Documentation.html">Documentation</a></li>
|
|
<li><a href="Donation.html">Donate</a></li>
|
|
<li><a href="https://sourceforge.net/p/veracrypt/discussion/" target="_blank">Forums</a></li>
|
|
</ul>
|
|
</div>
|
|
|
|
<div>
|
|
<p>
|
|
<a href="Documentation.html">Documentation</a>
|
|
<img src="arrow_right.gif" alt=">>" style="margin-top: 5px">
|
|
<a href="Technical%20Details.html">Technical Details</a>
|
|
<img src="arrow_right.gif" alt=">>" style="margin-top: 5px">
|
|
<a href="Modes%20of%20Operation.html">Modes of Operation</a>
|
|
</p></div>
|
|
|
|
<div class="wikidoc">
|
|
<h1>Modes of Operation</h1>
|
|
<div style="text-align:left; margin-top:19px; margin-bottom:19px; padding-top:0px; padding-bottom:0px">
|
|
<br style="text-align:left">
|
|
The mode of operation used by VeraCrypt for encrypted partitions, drives, and virtual volumes is XTS.
|
|
<br style="text-align:left">
|
|
<br style="text-align:left">
|
|
XTS mode is in fact XEX mode <a href="http://www.cs.ucdavis.edu/%7Erogaway/papers/offsets.pdf">
|
|
[12]</a>, which was designed by Phillip Rogaway in 2003, with a minor modification (XEX mode uses a single key for two different purposes, whereas XTS mode uses two independent keys).<br style="text-align:left">
|
|
<br style="text-align:left">
|
|
In 2010, XTS mode was approved by NIST for protecting the confidentiality of data on storage devices [24]. In 2007, it was also approved by the IEEE for cryptographic protection of data on block-oriented storage devices (IEEE 1619).</div>
|
|
<div style="text-align:left; margin-top:19px; margin-bottom:19px; padding-top:0px; padding-bottom:0px">
|
|
</div>
|
|
<h2 style="text-align:left; margin-top:19px; margin-bottom:19px; padding-top:0px; padding-bottom:0px">
|
|
<strong style="text-align:left">Description of XTS mode</strong>:</h2>
|
|
<div style="text-align:left; margin-top:19px; margin-bottom:19px; padding-top:0px; padding-bottom:0px">
|
|
<em style="text-align:left">C<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>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>)
|
|
<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>)) ^ (<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>)
|
|
<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>
|
|
<div style="text-align:left; margin-top:19px; margin-bottom:19px; padding-top:0px; padding-bottom:0px">
|
|
Where:</div>
|
|
<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">
|
|
<tbody style="text-align:left">
|
|
<tr style="text-align:left">
|
|
<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">
|
|
<sup style="text-align:left; font-size:85%"> <img src="gf2_mul.gif" alt="" width="10" height="10"></sup></td>
|
|
<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">
|
|
denotes multiplication of two polynomials over the binary field GF(2) modulo <em style="text-align:left">
|
|
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</td>
|
|
</tr>
|
|
<tr style="text-align:left">
|
|
<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">
|
|
<br style="text-align:left">
|
|
<em style="text-align:left">K</em>1</td>
|
|
<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">
|
|
<br style="text-align:left">
|
|
is the encryption key (256-bit for each supported cipher; i.e, AES, Serpent, and Twofish)</td>
|
|
</tr>
|
|
<tr style="text-align:left">
|
|
<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">
|
|
<br style="text-align:left">
|
|
<em style="text-align:left">K</em>2</td>
|
|
<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">
|
|
<br style="text-align:left">
|
|
is the secondary key (256-bit for each supported cipher; i.e, AES, Serpent, and Twofish)</td>
|
|
</tr>
|
|
<tr style="text-align:left">
|
|
<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">
|
|
<br style="text-align:left">
|
|
<em style="text-align:left">i</em></td>
|
|
<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">
|
|
<br style="text-align:left">
|
|
is the cipher block index within a data unit; for the first cipher block within a data unit,
|
|
<em style="text-align:left">i</em> = 0</td>
|
|
</tr>
|
|
<tr style="text-align:left">
|
|
<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">
|
|
<br style="text-align:left">
|
|
<em style="text-align:left">n</em></td>
|
|
<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">
|
|
<br style="text-align:left">
|
|
is the data unit index within the scope of <em style="text-align:left">K</em>1; for the first data unit,
|
|
<em style="text-align:left">n</em> = 0</td>
|
|
</tr>
|
|
<tr style="text-align:left">
|
|
<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">
|
|
<br style="text-align:left">
|
|
<em style="text-align:left">a</em></td>
|
|
<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">
|
|
<br style="text-align:left">
|
|
is a primitive element of Galois Field (2<sup style="text-align:left; font-size:85%">128</sup>) that corresponds to polynomial
|
|
<em style="text-align:left">x</em> (i.e., 2)</td>
|
|
</tr>
|
|
<tr style="text-align:left">
|
|
<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">
|
|
<br style="text-align:left">
|
|
<span style="text-align:left; font-size:10px; line-height:12px">Note: The remaining symbols are defined in the section
|
|
<a href="Notation.html" style="text-align:left; color:#0080c0; text-decoration:none">
|
|
Notation</a>. </span></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<div style="text-align:left; margin-top:19px; margin-bottom:19px; padding-top:0px; padding-bottom:0px">
|
|
<br style="text-align:left">
|
|
The size of each data unit is always 512 bytes (regardless of the sector size).</div>
|
|
<div style="text-align:left; margin-top:19px; margin-bottom:19px; padding-top:0px; padding-bottom:0px">
|
|
For further information pertaining to XTS mode, see e.g. <a href="http://www.cs.ucdavis.edu/%7Erogaway/papers/offsets.pdf" style="text-align:left; color:#0080c0; text-decoration:none">
|
|
[12]</a> and <a href="http://csrc.nist.gov/publications/nistpubs/800-38E/nist-sp-800-38E.pdf" style="text-align:left; color:#0080c0; text-decoration:none">
|
|
[24]</a>.</div>
|
|
<div style="text-align:left; margin-top:19px; margin-bottom:19px; padding-top:0px; padding-bottom:0px">
|
|
<a href="Header%20Key%20Derivation.html" style="text-align:left; color:#0080c0; text-decoration:none; font-weight:bold">Next Section >></a></div>
|
|
</div><div class="ClearBoth"></div></body></html>
|