192 lines
5.9 KiB
HTML
192 lines
5.9 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of NTFSDECRYPT</TITLE>
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</HEAD><BODY>
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<H1>NTFSDECRYPT</H1>
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Section: Maintenance Commands (8)<BR>Updated: June 2014<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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ntfsdecrypt - decrypt or update NTFS files encrypted according to EFS
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<B>ntfsdecrypt</B> [<I>options</I>] -k <I>key.pfx device file</I>
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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<B>ntfsdecrypt</B>
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decrypts a file from an unmounted device and print the decrypted data
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on the standard output.
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It can also update an encrypted file with the encryption key unchanged.
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<P>
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The NTFS file encryption (known as EFS) uses a two-level encryption :
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first, the file contents is encrypted with a random symmetric key, then
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this symmetric key is encrypted with the public keys of each of the users
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allowed to decrypt the file (RSA public key encryptions).
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<P>
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Three symmetric encryption modes are currently implemented in ntfsdecrypt :
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DESX (a DES variant), 3DES (triple DES) and AES_256 (an AES variant).
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<P>
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All the encrypted symmetric keys are stored along with the file in a
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special extended attribute named "$LOGGED_UTILITY_STREAM".
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Usually, at least two users are allowed to read the file : its owner and
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the recovery manager who is able to decrypt all the files in a company.
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When backing up an encrypted file, it is important to also backup the
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corresponding $LOGGED_UTILITY_STREAM, otherwise the file cannot be
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decrypted, even by the recovery manager. Also note that encrypted files
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are slightly bigger than apparent, and the option "efs_raw" has
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to be used when backing up encrypted files with ntfs-3g.
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<P>
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When ntfsdecrypt is used to update a file, the keys and the
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$LOGGED_UTILITY_STREAM are kept unchanged, so a single key file has to
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be designated.
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<P>
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Note : the EFS encryption is only available in professional versions
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of Windows;
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<A NAME="lbAE"> </A>
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<H2>OPTIONS</H2>
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Below is a summary of all the options that
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<B>ntfsdecrypt</B>
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accepts. Nearly all options have two equivalent names. The short name is
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preceded by
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<B>-</B>
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and the long name is preceded by
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<B>--</B>.
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Any single letter options, that don't take an argument, can be combined into a
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single command, e.g.
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<B>-fv</B>
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is equivalent to
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<B>-f -v</B>.
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Long named options can be abbreviated to any unique prefix of their name.
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<DL COMPACT>
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<DT id="1"><B>-i</B>, <B>--inode</B> NUM<DD>
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Display or update the contents of a file designated through its inode number
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instead of its name.
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<DT id="2"><B>-e</B>, <B>--encrypt</B><DD>
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Update an existing encrypted file and get the new contents from the
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standard input. The full public and private key file has to be designated,
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as the symmetric key is kept unchanged, so the private key is needed to
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extract it.
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<DT id="3"><B>-f</B>, <B>--force</B><DD>
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This will override some sensible defaults, such as not using a mounted volume.
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Use this option with caution.
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<DT id="4"><B>-k</B>, <B>--keyfile-name</B> key.pfx<DD>
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Define the file which contains the public and private keys in PKCS#12 format.
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This file obviously contains the keys of one of the users allowed to decrypt
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or update the file. It has to be extracted from Windows in PKCS#12 format
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(its usual suffix is .p12 or .pfx), and it is protected by a passphrase
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which has to be typed in for the keys to be extracted. This can be the
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key file of any user allowed to read the file, including the one of the
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recovery manager.
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<DT id="5"><B>-h</B>, <B>--help</B><DD>
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Show a list of options with a brief description of each one.
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<DT id="6"><B>-q</B>, <B>--quiet</B><DD>
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Suppress some debug/warning/error messages.
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<DT id="7"><B>-V</B>, <B>--version</B><DD>
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Show the version number, copyright and license of
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<B>ntfsdecrypt</B>.
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<DT id="8"><B>-v</B>, <B>--verbose</B><DD>
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Display more debug/warning/error messages.
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</DL>
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<A NAME="lbAF"> </A>
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<H2>EXAMPLES</H2>
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Display the contents of the file hamlet.doc in the directory Documents of
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the root of the NTFS file system on the device /dev/sda1
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<DL COMPACT><DT id="9"><DD>
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<P>
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<B>ntfsdecrypt -k foo.key /dev/sda1 Documents/hamlet.doc</B>
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<P>
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</DL>
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Update the file hamlet.doc
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<DL COMPACT><DT id="10"><DD>
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<P>
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<B>ntfsdecrypt -k foo.key /dev/sda1 Documents/hamlet.doc < new.doc</B>
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<P>
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</DL>
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<A NAME="lbAG"> </A>
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<H2>BUGS</H2>
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There are no known problems with
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<B>ntfsdecrypt</B>.
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If you find a bug please send an email describing the problem to the
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development team:
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<BR>
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<A HREF="mailto:ntfs-3g-devel@lists.sf.net">ntfs-3g-devel@lists.sf.net</A>
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<A NAME="lbAH"> </A>
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<H2>AUTHORS</H2>
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<B>ntfsdecrypt</B>
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was written by Yuval Fledel, Anton Altaparmakov and Yura Pakhuchiy.
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It was ported to ntfs-3g by Erik Larsson and upgraded by Jean-Pierre Andre.
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<A NAME="lbAI"> </A>
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<H2>AVAILABILITY</H2>
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<B>ntfsdecrypt</B>
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is part of the
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<B>ntfs-3g</B>
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package and is available from:
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<BR>
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<A HREF="http://www.tuxera.com/community/">http://www.tuxera.com/community/</A>
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<A NAME="lbAJ"> </A>
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<H2>SEE ALSO</H2>
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Read <B><A HREF="/cgi-bin/man/man2html?8+ntfs-3g">ntfs-3g</A></B>(8) for details on option efs_raw,
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<B><A HREF="/cgi-bin/man/man2html?8+ntfscat">ntfscat</A></B>(8),
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<B><A HREF="/cgi-bin/man/man2html?8+ntfsprogs">ntfsprogs</A></B>(8)
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="11"><A HREF="#lbAB">NAME</A><DD>
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<DT id="12"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="13"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="14"><A HREF="#lbAE">OPTIONS</A><DD>
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<DT id="15"><A HREF="#lbAF">EXAMPLES</A><DD>
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<DT id="16"><A HREF="#lbAG">BUGS</A><DD>
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<DT id="17"><A HREF="#lbAH">AUTHORS</A><DD>
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<DT id="18"><A HREF="#lbAI">AVAILABILITY</A><DD>
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<DT id="19"><A HREF="#lbAJ">SEE ALSO</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:06:14 GMT, March 31, 2021
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</BODY>
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</HTML>
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