NAME

       ntfsdecrypt - decrypt or update NTFS files encrypted according to EFS

SYNOPSIS

       ntfsdecrypt [options] -k key.pfx device file

DESCRIPTION

       ntfsdecrypt  decrypts  a file from an unmounted device and print the decrypted data on the
       standard output.  It can also update an encrypted file with the encryption key unchanged.

       The NTFS file encryption (known as EFS) uses a two-level  encryption  :  first,  the  file
       contents  is  encrypted  with a random symmetric key, then this symmetric key is encrypted
       with the public keys of each of the users allowed to decrypt  the  file  (RSA  public  key
       encryptions).

       Three  symmetric  encryption  modes are currently implemented in ntfsdecrypt : DESX (a DES
       variant), 3DES (triple DES) and AES_256 (an AES variant).

       All the encrypted symmetric keys are stored along with the  file  in  a  special  extended
       attribute named "$LOGGED_UTILITY_STREAM".  Usually, at least two users are allowed to read
       the file : its owner and the recovery manager who is able to decrypt all the  files  in  a
       company.   When  backing  up  an  encrypted  file,  it  is  important  to  also backup the
       corresponding $LOGGED_UTILITY_STREAM, otherwise the file cannot be decrypted, even by  the
       recovery  manager.  Also  note that encrypted files are slightly bigger than apparent, and
       the option "efs_raw" has to be used when backing up encrypted files with ntfs-3g.

       When ntfsdecrypt is used to update a file, the keys  and  the  $LOGGED_UTILITY_STREAM  are
       kept unchanged, so a single key file has to be designated.

       Note : the EFS encryption is only available in professional versions of Windows;

OPTIONS

       Below  is  a summary of all the options that ntfsdecrypt accepts.  Nearly all options have
       two equivalent names.  The short name is preceded by - and the long name  is  preceded  by
       --.  Any single letter options, that don't take an argument, can be combined into a single
       command, e.g.  -fv is equivalent to -f -v.  Long named options can be abbreviated  to  any
       unique prefix of their name.

       -i, --inode NUM
              Display  or  update  the  contents  of  a  file designated through its inode number
              instead of its name.

       -e, --encrypt
              Update an existing encrypted file and get the new contents from the standard input.
              The  full public and private key file has to be designated, as the symmetric key is
              kept unchanged, so the private key is needed to extract it.

       -f, --force
              This will override some sensible defaults, such as not using a mounted volume.  Use
              this option with caution.

       -k, --keyfile-name key.pfx
              Define the file which contains the public and private keys in PKCS#12 format.  This
              file obviously contains the keys of one of the users allowed to decrypt  or  update
              the  file.  It has to be extracted from Windows in PKCS#12 format (its usual suffix
              is .p12 or .pfx), and it is protected by a passphrase which has to be typed in  for
              the  keys to be extracted. This can be the key file of any user allowed to read the
              file, including the one of the recovery manager.

       -h, --help
              Show a list of options with a brief description of each one.

       -q, --quiet
              Suppress some debug/warning/error messages.

       -V, --version
              Show the version number, copyright and license of ntfsdecrypt.

       -v, --verbose
              Display more debug/warning/error messages.

EXAMPLES

       Display the contents of the file hamlet.doc in the directory Documents of the root of  the
       NTFS file system on the device /dev/sda1

              ntfsdecrypt -k foo.key /dev/sda1 Documents/hamlet.doc

       Update the file hamlet.doc

              ntfsdecrypt -k foo.key /dev/sda1 Documents/hamlet.doc < new.doc

BUGS

       There  are  no  known  problems  with ntfsdecrypt.  If you find a bug please send an email
       describing the problem to the development team:
       ntfs-3g-devel@lists.sf.net

AUTHORS

       ntfsdecrypt was written by Yuval Fledel, Anton Altaparmakov and Yura  Pakhuchiy.   It  was
       ported to ntfs-3g by Erik Larsson and upgraded by Jean-Pierre Andre.

AVAILABILITY

       ntfsdecrypt is part of the ntfs-3g package and is available from:
       http://www.tuxera.com/community/

SEE ALSO

       Read ntfs-3g(8) for details on option efs_raw,
       ntfscat(8), ntfsprogs(8)