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FreeOTFE
open-in-new
<h2 id="overview">Overview</h2> <p><i>FreeOTFE</i> was initially released by Sarah Dean in 2004, and was the first open source code disk encryption system that provided a modular architecture allowing 3rd parties to implement additional algorithms if needed. Older FreeOTFE licensing required that any modification to the program be placed in the <a href="/facts/Public_domain/YWKMDKw4">public domain</a>. This does not conform technically to section 3 of the <a href="/facts/Open_Source_definition/cRszXMSN">Open Source definition</a>. Newer program licensing omits this condition. The FreeOTFE license has not been approved by the <a href="http://opensource.org/licenses/alphabetical">Open Source Initiative</a> and is not certified to be labeled with the open-source certification mark. </p><p>This software is compatible with Linux encrypted volumes (e.g. <a href="/facts/LUKS/mKPeeurF">LUKS</a>, <a href="/facts/Cryptoloop/DEcxrlJG">cryptoloop</a>, <a href="/facts/Dm-crypt/DpsfvyrW">dm-crypt</a>), allowing data encrypted under Linux to be read (and written) freely. It was the first open source transparent disk encryption system to support <a href="/facts/Windows_Vista/IASEUCTB">Windows Vista</a> and PDAs.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a><a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a><a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a><a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> </p><p>Optional <a href="/facts/Two-factor_authentication/186gpx8R">two-factor authentication</a> using <a href="/facts/Smart_card/K7b9lowS">smart cards</a> and/or <a href="/facts/Hardware_security_module/dhpo8qoR">hardware security modules</a> (HSMs, also termed <a href="/facts/Security_tokens/0V55fErB">security tokens</a>)<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> was introduced in v4.0, using the <a href="/facts/PKCS11/LLtvbEfb">PKCS#11</a> (Cryptoki) standard developed by <a href="/facts/RSA_Laboratories/s8kfo2SF">RSA Laboratories</a>. </p><p><i>FreeOTFE</i> also allows any number of "hidden volumes" to be created, giving <a href="/facts/Plausible_deniability/KfCcDNLT">plausible deniability</a> and <a href="/facts/Deniable_encryption/pzfLjrpE">deniable encryption</a>, and also has the option of encrypting full partitions or disks (but not the system partition).<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> </p> <h2 id="portable-use">Portable use</h2> <p>FreeOTFE can be used in "portable" (or "traveller") mode, which allows it to be kept on a <a href="/facts/USB/XcIKWLyg">USB</a> drive or other portable media, together with its encrypted data, and carried around. This allows it to be used under <a href="/facts/Microsoft_Windows/bwhAhuSL">Microsoft Windows</a> without installation of the complete program to "mount" and access the encrypted data through a virtual disk. </p><p>The use of this mode requires installing <a href="/facts/Device_drivers/rDYnHU1G">device drivers</a> (at least temporarily) to create virtual disks, and as a consequence administrator rights are needed to start this traveller mode. As with most open source software that uses device drivers, the user must enable test signing<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> when running Windows Vista x64 and Windows 7 x64 systems.<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> </p> <h3>Driverless operation</h3> <p>Packaged with FreeOTFE is another program called "FreeOTFE Explorer",<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a> which provides a <i>driverless system</i> that allows encrypted disks to be used without administrator rights. </p><p>This allows FreeOTFE encrypted data to be used on (for example) public computers found in libraries or computer kiosks (<a href="/facts/Interactive_kiosk/kzvIrWve">interactive kiosks</a>), where administrator rights are unavailable. </p><p>Unlike FreeOTFE, FreeOTFE Explorer does not provide on-the-fly encryption through a virtual drive.<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a> Instead it lets files be stored and extracted from encrypted disk images, in a similar manner as <a href="/facts/ZIP_(file_format)/qDrrYIB9">ZIP</a> and <a href="/facts/RAR_(file_format)/cgHI6gnw">RAR</a> archives, by using a <a href="/facts/Windows_Explorer/oQW5yNnJ">Windows Explorer</a> like interface. </p> <h2 id="algorithms-implemented">Algorithms implemented</h2> <p>Due to its architecture, FreeOTFE provides great flexibility to the user with its encryption options. </p> <h3>Ciphers</h3> <p>FreeOTFE implements several ciphers, including: </p> <ul><li><a href="/facts/Advanced_Encryption_Standard/HdXGBY2Q">AES</a></li> <li><a href="/facts/Blowfish_(cipher)/H6fYatpd">Blowfish</a></li> <li><a href="/facts/CAST5/J7F8GWQc">CAST5</a> / <a href="/facts/CAST6/HdM0XCcd">CAST6</a></li> <li><a href="/facts/Data_Encryption_Standard/STfBjTGb">DES</a> / <a href="/facts/Triple_DES/sgzSD50P">Triple DES</a></li> <li><a href="/facts/MARS_(cryptography)/dMFo0P5v">MARS</a></li> <li><a href="/facts/RC6/XUqW8L36">RC6</a></li> <li><a href="/facts/Serpent_(cipher)/1gPjU4Fu">Serpent</a></li> <li><a href="/facts/Twofish/T1pjlttA">Twofish</a></li></ul> <p>It includes all <a href="/facts/National_Institute_of_Standards_and_Technology/gr9Fnh85">National Institute of Standards and Technology</a> (NIST) <a href="/facts/Advanced_Encryption_Standard/HdXGBY2Q">Advanced Encryption Standard</a> (AES) finalists, and all ciphers can be used with multiple different keylengths. </p> <h4>Cipher modes</h4> <p>FreeOTFE originally offered encryption using <a href="/facts/Cipher-block_chaining/vIUabB2z">cipher-block chaining</a> (CBC) with encrypted salt-sector initialization vector (<a href="/facts/ESSIV/VKWR7vfN">ESSIV</a>), though from v3.00 introduced <a href="/facts/Liskov-Rivest-Wagner/VKWR7vfN">LRW</a> and also the more secure <a href="/facts/Disk_encryption_theory/VKWR7vfN">XTS</a> mode, which supersedes LRW in the <a href="/facts/IEEE_P1619/Jewk1knM">IEEE P1619</a> standard for disk encryption. </p> <h3>Hashes</h3> <p>As with its cipher options, FreeOTFE offers many different hash algorithms: </p> <ul><li><a href="/facts/MD2_(cryptography)/eycTYeaf">MD2</a></li> <li><a href="/facts/MD4/V3dLUpRk">MD4</a></li> <li><a href="/facts/MD5/8WIXb9Dq">MD5</a></li> <li><a href="/facts/RIPEMD-160/z09kTSWX">RIPEMD-128</a></li> <li><a href="/facts/RIPEMD-160/z09kTSWX">RIPEMD-160</a></li> <li><a href="/facts/RIPEMD/z09kTSWX">RIPEMD-224</a></li> <li><a href="/facts/RIPEMD/z09kTSWX">RIPEMD-320</a></li> <li><a href="/facts/SHA-1/LDYCV1je">SHA-1</a></li> <li><a href="/facts/SHA-224/P59oPeGq">SHA-224</a></li> <li><a href="/facts/SHA-256/P59oPeGq">SHA-256</a></li> <li><a href="/facts/SHA-384/P59oPeGq">SHA-384</a></li> <li><a href="/facts/SHA-512/P59oPeGq">SHA-512</a></li> <li><a href="/facts/Tiger_(hash_function)/xLMxNVV5">Tiger</a></li> <li><a href="/facts/WHIRLPOOL/5d6erXP3">Whirlpool</a></li></ul> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Disk_encryption/v7E50jGw">Disk encryption</a></li> <li><a href="/facts/Disk_encryption_software/AxhTMVE4">Disk encryption software</a></li> <li><a href="/facts/On-the-fly_encryption/v7E50jGw">On-the-fly encryption</a></li> <li><a href="/facts/Comparison_of_disk_encryption_software/8hF593RQ">Comparison of disk encryption software</a></li></ul> <h2 id="external-links">External links</h2> <ul><li><a href="https://web.archive.org/web/20130531062457/http://freeotfe.org/">FreeOTFE</a> at the <a href="/facts/Wayback_Machine/nmQ3a6JC">Wayback Machine</a> (archived May 31, 2013)</li> <li><a href="https://sourceforge.net/projects/freeotfe.mirror/">FreeOTFE</a> on <a href="/facts/SourceForge/lxYAgUAX">SourceForge</a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>David A. Karp, Windows Vista annoyances, O'Reilly Media, Inc., 2008, ISBN 0-596-52762-4, page 5. <a href="/wiki/ISBN_(identifier)" target="_blank">/wiki/ISBN_(identifier)</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>LibreCrypt on GitHub <a href="https://github.com/t-d-k/librecrypt" target="_blank">https://github.com/t-d-k/librecrypt</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>FreeOTFE version history <a href="https://web.archive.org/web/20130305192701/http://freeotfe.org/docs/Main/version_history.htm" target="_blank">https://web.archive.org/web/20130305192701/http://freeotfe.org/docs/Main/version_history.htm</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Michael Mandaville, Citizen-Soldier Handbook: 101 Ways Every American Can Fight Terrorism, Dog Ear Publishing, 2009 ISBN 1-59858-671-8, page 253. <a href="/wiki/ISBN_(identifier)" target="_blank">/wiki/ISBN_(identifier)</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Gregory B. White, Wm. Arthur Conklin, Dwayne Williams, Roger L. Davis, Chuck Cothren, CompTIA Security+ All-in-One Exam Guide, Second Edition, McGraw Hill Professional, 2008, ISBN 0-07-160127-9, page 103. <a href="/wiki/ISBN_(identifier)" target="_blank">/wiki/ISBN_(identifier)</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Bryan Burns, Jennifer Stisa Granick, Steve Manzuik, Paul Guersch, Dave Killion, Nicolas Beauchesne, Security power tools, O'Reilly Media, Inc., 2007, ISBN 0-596-00963-1, page 523. <a href="/wiki/ISBN_(identifier)" target="_blank">/wiki/ISBN_(identifier)</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Security Token/Smartcard Support <a href="https://web.archive.org/web/20090401045551/http://www.freeotfe.org/docs/pkcs11_support.htm" target="_blank">https://web.archive.org/web/20090401045551/http://www.freeotfe.org/docs/pkcs11_support.htm</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>Partition/Entire Disk Based Volumes <a href="https://web.archive.org/web/20130124091508/http://freeotfe.org/docs/Main/advanced_topics.htm#level_3_heading_2" target="_blank">https://web.archive.org/web/20130124091508/http://freeotfe.org/docs/Main/advanced_topics.htm#level_3_heading_2</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>What is Windows 7 Test Mode <a href="https://social.technet.microsoft.com/Forums/windows/en-US/4c0e8b2a-a543-4c49-9629-8c4538acd0b5/what-is-windows-7-test-mode?forum=w7itproinstall" target="_blank">https://social.technet.microsoft.com/Forums/windows/en-US/4c0e8b2a-a543-4c49-9629-8c4538acd0b5/what-is-windows-7-test-mode?forum=w7itproinstall</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Additional Information for Windows Vista x64 and Windows 7 x64 Users <a href="https://web.archive.org/web/20130124091539/http://freeotfe.org/docs/Main/impact_of_kernel_driver_signing.htm" target="_blank">https://web.archive.org/web/20130124091539/http://freeotfe.org/docs/Main/impact_of_kernel_driver_signing.htm</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>FreeOTFE v. FreeOTFE Explorer Comparison <a href="https://web.archive.org/web/20130305192649/http://freeotfe.org/main_explorer_differences.html" target="_blank">https://web.archive.org/web/20130305192649/http://freeotfe.org/main_explorer_differences.html</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>FreeOTFE v. FreeOTFE Explorer Comparison <a href="https://web.archive.org/web/20130305192649/http://freeotfe.org/main_explorer_differences.html" target="_blank">https://web.archive.org/web/20130305192649/http://freeotfe.org/main_explorer_differences.html</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> </ol>