NTFSDECRYPT(8) - man - phpMan

NTFSDECRYPT(8)                         System Manager's Manual                        NTFSDECRYPT(8)



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  con‐
       tents 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 vari‐
       ant), 3DES (triple DES) and AES_256 (an AES variant).

       All  the encrypted symmetric keys are stored along with the file in a special extended attri‐
       bute 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  de‐
       scribing the problem to the development team:
       ntfs-3g-devel AT lists.net

AUTHORS
       ntfsdecrypt was written by Yuval Fledel, Anton Altaparmakov and Yura Pakhuchiy.  It was port‐
       ed 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:
       https://github.com/tuxera/ntfs-3g/wiki/

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



ntfs-3g 2021.8.22                             June 2014                               NTFSDECRYPT(8)