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diff --git a/doc/html/Modes of Operation.html b/doc/html/Modes of Operation.html new file mode 100644 index 00000000..3ea4e8c3 --- /dev/null +++ b/doc/html/Modes of Operation.html @@ -0,0 +1,130 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" + "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> +<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" 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="https://www.veracrypt.fr/en/Home.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/">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.html"> +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.html">Next Section >></a></div> +</div><div class="ClearBoth"></div></body></html>
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