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ecryptfs(7)                        eCryptfs                        ecryptfs(7)



NAME
       eCryptfs - an enterprise-class cryptographic filesystem for linux


SYNOPSIS
       mount -t ecryptfs [SRC DIR] [DST DIR] -o [OPTIONS]


DESCRIPTION
       eCryptfs  is  a POSIX-compliant enterprise-class stacked cryptographic filesystem for Linux. It is derived from
       Erez Zadok's Cryptfs, implemented through the FiST  framework  for  generating  stacked  filesystems.  eCryptfs
       extends Cryptfs to provide advanced key management and policy features.  eCryptfs stores cryptographic metadata
       in the header of each file written, so that encrypted files can be copied  between  hosts;  the  file  will  be
       decryptable  with  the  proper key, and there is no need to keep track of any additional information aside from
       what is already in the encrypted file itself. Think of eCryptfs as a sort of "gnupgfs."


OPTIONS
       KERNEL OPTIONS

            Parameters that apply to the eCryptfs kernel module.


       ecryptfs_sig=(fekek_sig)
              Specify the signature of the mount wide authentication token. The authentication token must  be  in  the
              kernel  keyring before the mount is performed. ecryptfs-manager or the eCryptfs mount helper can be used
              to construct the authentication token and add it to the keyring prior to mounting.

       ecryptfs_fnek_sig=(fnek_sig)
              Specify the signature of the mount wide authentication token used for filename crypto.  The  authentica-
              tion must be in the kernel keyring before mounting.

       ecryptfs_cipher=(cipher)
              Specify the symmetric cipher to be used on a per file basis

       ecryptfs_key_bytes=(key_bytes)
              Specify  the keysize to be used with the selected cipher. If the cipher only has one keysize the keysize
              does not need to be specified.

       ecryptfs_passthrough
              Allows for non-eCryptfs files to be read and written from within  an  eCryptfs  mount.  This  option  is
              turned off by default.

       no_sig_cache
              Do  not  check  the mount key signature against the values in the user's ~/.ecryptfs/sig-cache.txt file.
              This is useful for such things as non-interactive setup scripts, so that the mount helper does not  stop
              and prompt the user in the event that the key sig is not in the cache.

       ecryptfs_encrypted_view
              This  option  provides  a  unified encrypted file format of the eCryptfs files in the lower mount point.
              Currently, it is only useful if the lower mount point contains files with the  metadata  stored  in  the
              extended  attribute.   Upon a file read in the upper mount point, the encrypted version of the file will
              be presented with the metadata in the file header instead of the xattr.   Files  cannot  be  opened  for
              writing when this option is enabled.

       ecryptfs_xattr
              Store  the  metadata  in  the extended attribute of the lower files rather than the header region of the
              lower files.

       verbose
              Log ecryptfs information to /var/log/messages.  Do not run eCryptfs in verbose-mode unless you are doing
              so  for  the  sole  purpose of development, since secret values will be written out to the system log in
              that case.


       MOUNT HELPER OPTIONS

              Parameters that apply to the eCryptfs mount helper.


       key=(keytype):[KEY MODULE OPTIONS]
              Specify the type of key to be used when mounting eCryptfs.

       ecryptfs_enable_filename_crypto=(y/N)
              Specify whether filename encryption should be enabled. If not, the mount helper will not prompt the user
              for the filename encryption key signature.

       verbosity=0/1
              If  verbosity=1, the mount helper will ask you for missing values (default).  Otherwise, if verbosity=0,
              it will not ask for missing values and will fail if required values are omitted.


       KEY MODULE OPTIONS

              Parameters that apply to individual key modules have the alias for the key module in the prefix  of  the
              parameter  name.  Key  modules are pluggable, and which key modules are available on any given system is
              dependent upon whatever happens to be installed in /usr/lib*/ecryptfs/. By default, this includes, at  a
              minimum, "passphrase" and "openssl."


       passphrase_passwd=(passphrase)
              The  actual  password  is password. Since the password is visible to utilities (like ps under Unix) this
              form should only be used where security is not important.

       passphrase_passwd_file=(filename)
              The password should be specified in a file with passwd=(passphrase). It is highly reccomended  that  the
              file be stored on a secure medium such as a personal usb key.

       passphrase_passwd_fd=(file descriptor)
              The password is specified through the specified file descriptor.

       passphrase_salt=(hex value)
              The salt should be specified as a 16 digit hex value.

       openssl_keyfile=(filename)
              The filename should be the filename of a file containing an RSA SSL key.

       openssl_passwd_file=(filename)
              The  password  should  be  specified in a file with openssl_passwd=(openssl-password). It is highly rec-
              comended that the file be stored on a secure medium such as a personal usb key.

       openssl_passwd_fd=(file descriptor)
              The password is specified through the specified file descriptor.

       openssl_passwd=(password)
              The password can be specified on the command line. Since the password is visible in the process list, it
              is highly recommended to use this option only for testing purposes.


EXAMPLE
       The  following  command  will layover mount eCryptfs on /secret with a passphrase contained in a file stored on
       secure media mounted at /mnt/usb/.

       mount -t ecryptfs -o key=passphrase:passphrase_passwd_file=/mnt/usb/file.txt /secret /secret



       Where file.txt contains the contents "passphrase_passwd=[passphrase]".


SEE ALSO
       mount(8)

       /usr/share/doc/ecryptfs-utils/ecryptfs-faq.html

       http://launchpad.net/ecryptfs/


NOTES
       Do not run eCryptfs in verbose-mode unless you are doing so for the sole purpose of development,  since  secret
       values  will  be  written  out to the system log in that case. Make certain that your eCryptfs mount covers all
       locations where your applications may write sensitive data. In addition, use  dm-crypt  to  encrypt  your  swap
       space with a random key on boot, or see ecryptfs-setup-swap(1).

       Passphrases have a maximum length of 64 characters.


BUGS
       Please   post   bug   reports   to   the   eCryptfs   bug   tracker   on   Launchpad.net:  https://bugs.launch-
       pad.net/ecryptfs/+filebug.

       For kernel bugs, please follow the procedure detailed in Documentation/oops-tracing.txt to help us  figure  out
       what is happening.


AUTHOR
       This  manpage  was (re-)written by Dustin Kirkland <kirklandATcanonical.com> for Ubuntu systems (but may be used
       by others).  Permission is granted to copy, distribute and/or modify this document under the terms of  the  GNU
       General Public License, Version 2 or any later version published by the Free Software Foundation.

       On  Debian  systems,  the  complete  text  of the GNU General Public License can be found in /usr/share/common-
       licenses/GPL.



ecryptfs-utils                    2009-03-24                       ecryptfs(7)