README: Describe storage overhead

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Jakob Unterwurzacher 2015-11-01 12:14:59 +01:00
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GoCryptFS [![Build Status](https://travis-ci.org/rfjakob/gocryptfs.svg?branch=master)](https://travis-ci.org/rfjakob/gocryptfs)
==============
An encrypted overlay filesystem focused on security and correctness.
An encrypted overlay filesystem written in Go.
gocryptfs is built on top the excellent
[go-fuse](https://github.com/hanwen/go-fuse) FUSE library and its
@ -8,20 +8,19 @@ LoopbackFileSystem API.
This project was inspired by [EncFS](https://github.com/vgough/encfs)
and strives to fix its security issues (see EncFS tickets 9, 13, 14, 16).
For details on the security of GoCryptFS see the
For details on the security of gocryptfs see the
[SECURITY.md](SECURITY.md) document.
Current Status
--------------
* First public release
* Feature-complete
* Feature-complete and working
* Passes the fuse-xfstests "generic" tests with one exception, results: [XFSTESTS.md](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 exceptions generic/035. This is a limitation 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 a Mac OS X port.
* Only Linux operation has been tested. Help wanted for Mac OS X verification.
Install
-------
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-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
-----------
* 28 bytes of storage overhead per block (16 bytes auth tag, 12 byte nonce)
* uses openssl through [spacemonkeygo/openssl](https://github.com/spacemonkeygo/openssl)
for a 3x speedup compared to `crypto/cipher` (see [go-vs-openssl.md](openssl_benchmark/go-vs-openssl.md) for details
* uses openssl through [spacemonkeygo/openssl](https://github.com/spacemonkeygo/openssl)
for a 3x speedup compared to `crypto/cipher` (see [go-vs-openssl.md](openssl_benchmark/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