153 lines
5.5 KiB
Markdown
153 lines
5.5 KiB
Markdown
GoCryptFS [](https://travis-ci.org/rfjakob/gocryptfs) 
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==============
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An encrypted overlay filesystem written in Go.
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gocryptfs is built on top the excellent
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[go-fuse](https://github.com/hanwen/go-fuse) FUSE library and its
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LoopbackFileSystem API.
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This project was inspired by EncFS and strives to fix its security
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issues while providing good performance.
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For details on the security of gocryptfs see the
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[SECURITY.md](Documentation/SECURITY.md) design document.
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Current Status
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--------------
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Beta. You are advised to keep a backup of your data outside of gocryptfs, in
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addition to storing the *master key* in a safe place (the master key is printed
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when mounting).
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Only Linux is supported at the moment. Help wanted for a Mac OS X port.
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Testing
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-------
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gocryptfs comes with is own test suite that is constantly expanded as features are
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added. Run it using `./test.bash`. It takes about 30 seconds and requires FUSE
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as it mounts several test filesystems.
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In addition, I have ported `xfstests` to FUSE, the result is the
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[fuse-xfstests](https://github.com/rfjakob/fuse-xfstests) project. gocryptfs
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passes the "generic" tests with one exception, results: [XFSTESTS.md](Documentation/XFSTESTS.md)
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A lot of work has gone into this. The testing has found bugs in gocryptfs
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as well as in go-fuse.
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The one exception is generic/035, see [go-fuse issue 55](https://github.com/hanwen/go-fuse/issues/55)
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for details. While this is a POSIX violation, I do not see any real-world impact.
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Install
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-------
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$ go get github.com/rfjakob/gocryptfs
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Use
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---
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Quickstart:
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$ mkdir cipher plain
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$ $GOPATH/bin/gocryptfs --init cipher
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[...]
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$ $GOPATH/bin/gocryptfs cipher plain
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[...]
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$ echo test > plain/test.txt
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$ ls -l cipher
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total 8
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-rw-rw-r--. 1 user user 33 7. Okt 23:23 0ao8Hyyf1A-A88sfNvkUxA==
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-rw-rw-r--. 1 user user 233 7. Okt 23:23 gocryptfs.conf
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$ fusermount -u plain
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See [MANPAGE.md](Documentation/MANPAGE.md) for a description of available options. If you already
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have gocryptfs installed, run `./MANPAGE-render.bash` to bring up the rendered manpage in
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the pager (requires pandoc).
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Storage Overhead
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----------------
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* Empty files take 0 bytes on disk
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* 18 byte file header for non-empty files (2 bytes version, 16 bytes random file id)
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* 28 bytes of storage overhead per 4kB block (12 byte nonce, 16 bytes auth tag)
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Performance
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-----------
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gocryptfs uses openssl through
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[spacemonkeygo/openssl](https://github.com/spacemonkeygo/openssl)
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for a 3x speedup compared to Go's builtin AES-GCM implementation (see
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[go-vs-openssl.md](openssl_benchmark/go-vs-openssl.md) for details).
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Run `./benchmark.bash` to run the benchmarks.
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The output should look like this:
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./benchmark.bash
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gocryptfs v0.3.1-30-gd69e0df-dirty; on-disk format 2
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PASS
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BenchmarkStreamWrite-2 100 12246070 ns/op 85.63 MB/s
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BenchmarkStreamRead-2 200 9125990 ns/op 114.90 MB/s
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BenchmarkCreate0B-2 10000 101284 ns/op
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BenchmarkCreate1B-2 10000 178356 ns/op 0.01 MB/s
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BenchmarkCreate100B-2 5000 361014 ns/op 0.28 MB/s
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BenchmarkCreate4kB-2 5000 375035 ns/op 10.92 MB/s
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BenchmarkCreate10kB-2 3000 491071 ns/op 20.85 MB/s
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ok github.com/rfjakob/gocryptfs/integration_tests 17.216s
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Changelog
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---------
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v0.6
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* **Wide-block filename encryption using EME + DirIV**
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* EME (ECB-Mix-ECB) provides even better security than CBC as it fixes
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the prefix leak. The used Go EME implementation is
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https://github.com/rfjakob/eme which is, as far as I know, the first
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implementation of EME in Go.
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* This is a forwards-compatible change. gocryptfs v0.6 can mount filesystems
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created by earlier version but not the other way round.
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* New command-line option:
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* `-emenames`: Enable EME filename encryption (default true)
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v0.5
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* **Stronger filename encryption: DirIV**
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* Each directory gets a random 128 bit file name IV on creation,
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stored in `gocryptfs.diriv`
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* This makes it impossible to identify identically-named files across
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directories
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* A single-entry IV cache brings the performance cost of DirIV close to
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zero for common operations (see performance.txt)
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* This is a forwards-compatible change. gocryptfs v0.5 can mount filesystems
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created by earlier version but not the other way round.
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* New command-line option:
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* `-diriv`: Use the new per-directory IV file name encryption (default true)
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* `-scryptn`: allows to set the scrypt cost parameter N. This option
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can be used for faster mounting at the cost of lower brute-force
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resistance. It was mainly added to speed up the automated tests.
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v0.4
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* New command-line options:
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* `-plaintextnames`: disables filename encryption, added on user request
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* `-extpass`: calls an external program for prompting for the password
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* `-config`: allows to specify a custom gocryptfs.conf path
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* Add `FeatureFlags` gocryptfs.conf paramter
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* This is a config format change, hence the on-disk format is incremented
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* Used for ext4-style filesystem feature flags. This should help avoid future
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format changes. The first user is `-plaintextnames`.
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* On-disk format 2
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v0.3
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* **Add a random 128 bit file header to authenticate file->block ownership**
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* This is an on-disk-format change
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* On-disk format 1
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v0.2
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* Replace bash daemonization wrapper with native Go implementation
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* Better user feedback on mount failures
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v0.1
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* First release
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* On-disk format 0
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See https://github.com/rfjakob/gocryptfs/tags for the release dates and associated
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git tags.
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