Last Change: 2018-09-07, 16:50
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gocryptfs − mount an encrypted directory
Initialize encrypted filesystem
gocryptfs −init [OPTIONS] CIPHERDIR
Mount
gocryptfs [OPTIONS] CIPHERDIR MOUNTPOINT −o COMMA−SEPARATED−OPTIONS (#o-comma-separated-options)
Change password
gocryptfs −passwd [OPTIONS] CIPHERDIR
Available options are listed below.
−aessiv
Use the AES−SIV encryption mode. This is slower than GCM but is secure with deterministic nonces as used in "−reverse" mode.
−allow_other
By default, the Linux kernel prevents any other user (even root) to access a mounted FUSE filesystem. Settings this option allows access for other users, subject to file permission checking. Only works if user_allow_other is set in /etc/fuse.conf. This option is equivalent to "allow_other" plus "default_permissions" described in fuse(8).
−config string
Use specified config file instead of CIPHERDIR/gocryptfs.conf
−cpuprofile string
Write cpu profile to specified file
−ctlsock string
Create a control socket at the specified location. The socket can be used to decrypt and encrypt paths inside the filesystem. When using this option, make sure that the direcory you place the socket in is not world−accessible. For example, /run/user/UID/my.socket would be suitable.
−d, −debug
Enable debug output
−extpass string
Use an external program (like ssh−askpass) for the password prompt. The program should return the password on stdout, a trailing newline is stripped by gocryptfs. Using something like "cat /mypassword.txt" allows to mount the gocryptfs filesytem without user interaction.
−fg, −f
Stay in the foreground instead of forking away. Implies "−nosyslog". For compatability, "−f" is also accepted, but "−fg" is preferred.
−forcedecode
Force decode of encrypted files even if the integrity check fails, instead of failing with an IO error. Warning messages are still printed to syslog if corrupted files are encountered. It can be useful to recover files from disks with bad sectors or other corrupted media. It shall not be used if the origin of corruption is unknown, specially if you want to run executable files.
For corrupted media, note that you probably want to use dd_rescue(1) instead, which will recover all but the corrupted 4kB block.
This option makes no sense in reverse mode. It requires gocryptfs to be compiled with openssl support and implies −openssl true. Because of this, it is not compatible with −aessiv, that uses built−in Go crypto.
Setting this option forces the filesystem to read−only and noexec.
−fsname string
Override the filesystem name (first column in df −T). Can also be passed as "−o fsname=" and is equivalent to libfuse's option of the same name. By default, CIPHERDIR is used.
−fusedebug
Enable fuse library debug output
−init
Initialize encrypted directory
−ko
Pass additonal mount options to the kernel (comma−separated list). FUSE filesystems are mounted with "nodev,nosuid" by default. If gocryptfs runs as root, you can enable device files by passing the opposite mount option, "dev", and if you want to enable suid−binaries, pass "suid". "ro" (equivalent to passing the "−ro" option) and "noexec" may also be interesting. For a complete list see the section FILESYSTEM−INDEPENDENT MOUNT OPTIONS in mount(8).
−longnames
Store names longer than 176 bytes in extra files (default true) This flag is useful when recovering old gocryptfs filesystems using "−masterkey". It is ignored (stays at the default) otherwise.
−masterkey string
Use a explicit master key specified on the command line. This option can be used to mount a gocryptfs filesystem without a config file. Note that the command line, and with it the master key, is visible to anybody on the machine who can execute "ps −auxwww". This is meant as a recovery option for emergencies, such as if you have forgotten your password.
Example master key:
6f717d8b−6b5f8e8a−fd0aa206−778ec093−62c5669b−abd229cd−241e00cd−b4d6713d
−memprofile string
Write memory profile to the specified file. This is useful when debugging memory usage of gocryptfs.
−nonempty
Allow mounting over non−empty directories. FUSE by default disallows this to prevent accidential shadowing of files.
−noprealloc
Disable preallocation before writing. By default, gocryptfs preallocates the space the next write will take using fallocate(2) in mode FALLOC_FL_KEEP_SIZE. The preallocation makes sure it cannot run out of space in the middle of the write, which would cause the last 4kB block to be corrupt and unreadable.
On ext4, preallocation is fast and does not cause a noticeable performance hit. Unfortunately, on Btrfs, preallocation is very slow, especially on rotational HDDs. The "−noprealloc" option gives users the choice to trade robustness against out−of−space errors for a massive speedup.
For benchmarks and more details of the issue see https://github.com/rfjakob/gocryptfs/issues/63 .
−nosyslog
Diagnostic messages are normally redirected to syslog once gocryptfs daemonizes. This option disables the redirection and messages will continue be printed to stdout and stderr.
−notifypid int
Send USR1 to the specified process after successful mount. This is used internally for daemonization.
−o COMMA−SEPARATED−OPTIONS
For compatibility with mount(1), options are also accepted as "−o COMMA−SEPARATED−OPTIONS" at the end of the command line. For example, "−o q,zerokey" is equivalent to passing "−q −zerokey".
−openssl bool/"auto"
Use OpenSSL instead of built−in Go crypto (default "auto"). Using built−in crypto is 4x slower unless your CPU has AES instructions and you are using Go 1.6+. In mode "auto", gocrypts chooses the faster option.
−passfile string
Read password from the specified file. This is a shortcut for specifying '−extpass="/bin/cat −− FILE"'.
−passwd
Change the password. Will ask for the old password, check if it is correct, and ask for a new one.
This can be used together with −masterkey if you forgot the password but know the master key. Note that without the old password, gocryptfs cannot tell if the master key is correct and will overwrite the old one without mercy. It will, however, create a backup copy of the old config file as gocryptfs.conf.bak. Delete it after you have verified that you can access your files with the new password.
−plaintextnames
Do not encrypt file names and symlink targets
−q, −quiet
Quiet − silence informational messages
−raw64
Use unpadded base64 encoding for file names. This gets rid of the trailing "\=\=". A filesystem created with this option can only be mounted using gocryptfs v1.2 and higher.
−reverse
Reverse mode shows a read−only encrypted view of a plaintext directory. Implies "−aessiv".
−ro
Mount the filesystem read−only
−scryptn int
scrypt cost parameter expressed as scryptn=log2(N). Possible values are 10 to 28, representing N=2^10 to N=2^28.
Setting this to a lower value speeds up mounting and reduces its memory needs, but makes the password susceptible to brute−force attacks. The default is 16.
−serialize_reads
The kernel usually submits multiple concurrent reads to service userspace requests and kernel readahead. gocryptfs serves them concurrently and in arbitrary order. On backing storage that performs poorly for concurrent or out−of−order reads (like Amazon Cloud Drive), this behavoir can cause very slow read speeds.
The −serialize_reads option does two things: (1) reads will be submitted one−by−one (no concurrency) and (2) gocryptfs tries to order the reads by file offset order.
The ordering requires gocryptfs to wait a certain time before submitting a read. The serialization introduces extra locking. These factors will limit throughput to below 70MB/s.
For more details visit https://github.com/rfjakob/gocryptfs/issues/92 .
−speed
Run crypto speed test. Benchmark Go's built−in GCM against OpenSSL (if available). The library that will be selected on "−openssl=auto" (the default) is marked as such.
−version
Print version and exit. The output contains three fields seperated by ";". Example: "gocryptfs v1.1.1−5−g75b776c; go−fuse 6b801d3; 2016−11−01 go1.7.3". Field 1 is the gocryptfs version, field 2 is the version of the go−fuse library, field 3 is the compile date and the Go version that was used.
−wpanic
When encountering a warning, panic and exit immediately. This is useful in regression testing.
−zerokey
Use all−zero dummy master key. This options is only intended for automated testing as it does not provide any security.
−−
Stop option parsing. Helpful when CIPHERDIR may start with a dash "−".
Create an encrypted filesystem in directory "g1" and mount it on "g2":
mkdir g1 g2 gocryptfs −init g1 gocryptfs g1 g2
Mount an ecrypted view of joe's home directory using reverse mode:
mkdir /home/joe.crypt gocryptfs −init −reverse /home/joe gocryptfs −reverse /home/joe /home/joe.crypt
0: success
12: password incorrect
other: please check the error message
github.com/rfjakob.