GoCryptFS

An encrypted overlay filesystem written in Go.

gocryptfs is built on top the excellent go-fuse FUSE library and its LoopbackFileSystem API.

This project was inspired by EncFS and strives to fix its security issues (see EncFS tickets 9, 13, 14, 16). For details on the security of gocryptfs see the SECURITY.md document.

Current Status

Feature-complete and working
Passes the fuse-xfstests "generic" tests with one exception, results: XFSTESTS.md
A lot of work has gone into this. The testing has found bugs in gocryptfs as well as in go-fuse.
The one exception is generic/035. This is a limitation in go-fuse, check out https://github.com/hanwen/go-fuse/issues/55 for details.
However, gocryptfs needs more real-world testing - please report any issues via github.
Only Linux operation has been tested. Help wanted for Mac OS X verification.

Install

$ go get github.com/rfjakob/gocryptfs

Use

$ mkdir cipher plain
$ $GOPATH/bin/gocryptfs --init cipher
  [...]
$ $GOPATH/bin/gocryptfs cipher plain
  [...]
$ echo test > plain/test.txt
$ ls -l cipher
  total 8
  -rw-rw-r--. 1 user  user   33  7. Okt 23:23 0ao8Hyyf1A-A88sfNvkUxA==
  -rw-rw-r--. 1 user  user  233  7. Okt 23:23 gocryptfs.conf
$ fusermount -u plain

Storage Overhead

Empty files take 0 bytes on disk
18 byte file header for non-empty files (2 bytes version, 16 bytes random file id)
28 bytes of storage overhead per 4kB block (12 byte nonce, 16 bytes auth tag)

Performance

uses openssl through spacemonkeygo/openssl for a 3x speedup compared to crypto/cipher (see go-vs-openssl.md for details

Run ./benchmark.bash to run the test suite and the streaming read/write benchmark. The benchmark is run twice, first with native Go crypto and second using openssl.

The output should look like this:

$ ./benchmark.bash
[...]
BenchmarkStreamWrite         100      11816665 ns/op      88.74 MB/s
BenchmarkStreamRead          200       7848155 ns/op     133.61 MB/s
ok      github.com/rfjakob/gocryptfs    9.407s

Changelog

v0.3 * Add file header that contains a random id to authenticate blocks * This is an on-disk-format change * On-disk format 1

v0.2 * Replace bash daemonization wrapper with native Go implementation * Better user feedback on mount failures

v0.1 * First release * On-disk format 0

See https://github.com/rfjakob/gocryptfs/releases for the release dates and associated tags.