Warning
This crate hasn't been audited, it's using ring
crate which is a well known library, so in principle at least the primitives should offer as similar level of security.
This is still under development. Please do not use it with sensitive data just yet. Please wait for a
stable release and maybe an audit.
It's mostly ideal for experimental and learning projects.
An encrypted file system that is mounted with FUSE on Linux. It can be used to create encrypted directories.
You can then safely backup the encrypted folder on an untrusted server without worrying about the data being exposed.
You can also store it in any cloud storage like Google Drive, Dropbox, etc. and have it synced across multiple devices.
You can use it as CLI or build your custom FUSE implementation with it.
- It keeps all encrypted data and master encryption key in a dedicated directory with files structured on inodes (with
meta
info), files for binary content and directories with files/directories entries. All data, metadata and also filenames
are encrypted. For new files it generates inode number randomly in
u64
space so it reduces the chance of conflicts when used offline and synced later. - Password is collected from CLI and it's saved in OS keyring while app is running. This is because of safety reasons we clear the password from memory on inactivity and we reload it again from keyring just when needed.
- Master encryption key is also encrypted with another key derived from the password. This gives the ability to change the password without re-encrypting all data, we just re-encrypt the master key.
- Files are encrypted in chunks of 256KB, so when making a change we just re-encrypt those chunks.
- Fast seek on read and write, so if you're watching a movie you you can seek to any position and that would be very fast. This is because we can seek to particular chunk.
- Encryption key is
zeroize
d in mem on idle. Also it'smlock
ed while used to prevent being moved to swap. It's alsomprotect
ed while not read.
In progress:
- ensure file integrity by saving each change to WAL, so on crash or power loss on next start we apply the pending changes. This makes the write operations atomic.
- multiple writes in parallel to the same file, ideal for torrent like applications
- it's fully async built upon tokio and fuse3
- ring for encryption and argon2 for key derivation function (creating key used to encrypt master encryption key from password)
- rand_chacha for random generators
- secrecy for keeping pass and encryption keys safe in memory and zeroing them when not used. It keeps encryption keys in memory only while being used and when not active it will release and zeroing them from memory
- password can be saved in OS keyring using keyring
- tracing for logs
Get the image
docker pull xorio42/rencfs
Start a container to set up mount in it
docker run -it --device /dev/fuse --cap-add SYS_ADMIN --security-opt apparmor:unconfined xorio42/rencfs:latest /bin/sh
In the container create mount and data directories
mkdir fsmnt && mkdir fsdata
Start rencfs
rencfs --mount-point fsmnt --data-dir fsdata
Enter a password for encryption.
Get the container ID
docker ps
In another terminal attach to running container with the above ID
docker exec -it <ID> /bin/sh
From here you can play with it by creating files in fsmnt
directory
cd fsmnt
mkdir 1
ls
echo "test" > 1/test
cat 1/test
You can use it as a command line tool to mount an encrypted file system, or directly using the library to build your own binary (for library, you can follow the documentation).
To use the encrypted file system, you need to have FUSE installed on your system. You can install it by running the following command (or based on your distribution).
Arch
sudo pacman -Syu && sudo pacman -S fuse3
Ubuntu
sudo apt-get update && sudo apt-get -y install fuse3
You can install the encrypted file system binary using the following command
yay -Syu && yay -S rencfs
You can install the encrypted file system binary using the following command
cargo install rencfs
A basic example of how to use the encrypted file system is shown below
rencfs mount --mount-point MOUNT_POINT --data-dir DATA_DIR
MOUNT_POINT
act as a client, and mount FUSE at given pathDATA_DIR
where to store the encrypted data with the sync provider. But it needs to be on the same filesystem as the data-dir
It will prompt you to enter a password to encrypt/decrypt the data.
The master encryption key is stored in a file and encrypted with a key derived from the password. This offers the possibility to change the password without needing to re-encrypt the whole data. This is done by decrypting the master key with the old password and re-encrypting it with the new password.
To change the password, you can run the following command
rencfs passwd --data-dir DATA_DIR
DATA_DIR
where the encrypted data is stored
It will prompt you to enter the old password and then the new password.
You can specify the encryption algorithm adding this argument to the command line
--cipher CIPHER ...
Where CIPHER
is the encryption algorithm. You can check the available ciphers with rencfs --help
.
Default value is ChaCha20Poly1305
.
You can specify the log level adding the --log-level
argument to the command line. Possible
values: TRACE
, DEBUG
, INFO
(default), WARN
, ERROR
.
rencfs --log-level LEVEL ...
You can see more here
You can compile it, run it, and give it a quick try in browser. After you start it from above
sudo apt-get update && sudo apt-get install fuse3
mkdir mnt && mkdir data
cargo run --release -- mount -m mnt -d data
Open another terminal
cd mnt
mkdir a && cd a
echo "test" > test.txt
cat test.txt
git clone git@github.com:radumarias/rencfs.git && cd rencfs
To build from source, you need to have Rust installed, you can see more details on how to install it here.
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
Accordingly, it is customary for Rust developers to include this directory in their PATH
environment variable.
During installation rustup
will attempt to configure the PATH
. Because of differences between platforms, command
shells,
and bugs in rustup
, the modifications to PATH
may not take effect until the console is restarted, or the user is
logged out, or it may not succeed at all.
If, after installation, running rustc --version
in the console fails, this is the most likely reason.
In that case please add it to the PATH
manually.
Project is setup to use nighlty
toolchain in rust-toolchain.toml
, on first build you will see it fetch the nightly.
Also, these deps are required (or based on your distribution):
sudo pacman -Syu && sudo pacman -S fuse3 base-devel
sudo apt-get update && sudo apt-get install fuse3 build-essential
sudo dnf update && sudo dnf install fuse3 && dnf install @development-tools
cargo build
cargo build --release
cargo run -- --mount-point MOUNT_POINT --data-dir DATA_DIR
This is using cargo-generate-rpm
cargo install cargo-generate-rpm
cargo build --release
cargo generate-rpm
The generated RPM will be located here: target/generate-rpm
.
cd target/generate-rpm/
sudo dnf localinstall rencfs-xxx.x86_64.rpm
See here how to configure for VsCode
And here for RustRover
You can use the .devcontainer
directory from the project to start a container with all the necessary tools to build and run the app.
- Plan is to implement it also on macOS and Windows
- A systemd service is being worked on rencfs-daemon
- A GUI is on the way rencfs_desktop
- Mobile apps for Android and iOS are on the way
Feel free to fork it, change and use it in any way that you want. If you build something interesting and feel like sharing pull requests are always appreciated.
Aes256Gcm
is slightly faster thanChaCha20Poly1305
by a factor of1.66
on average. This is because of the hardware acceleration of AES on most CPUs via AES-NI. But where hardware acceleration is not availableChaCha20Poly1305
is faster
- If you have hardware acceleration (e.g. AES-NI), then AES-GCM provides better performance. On my benchmarks, it was
faster by a factor of 1.28 on average.
If you do not have hardware acceleration, AES-GCM is either slower than ChaCha20-Poly1305, or it leaks your encryption keys in cache timing. - AES-GCM can target multiple security levels (128-bit, 192-bit, 256-bit), whereas ChaCha20-Poly1305 is only defined at the 256-bit security level.
- Nonce size:
- AES-GCM: Varies, but standard is 96 bits (12 bytes). If you supply a longer nonce, this gets hashed down to 16 bytes.
- ChaCha20-Poly1305: The standardized version uses 96-bit nonces (12 bytes), but the original used 64-bit nonces (8 bytes).
- Wearout of a single (key, nonce) pair:
- AES-GCM: Messages must be less than 2^32 – 2 blocks (a.k.a.
2^36 – 32 bytes
, a.k.a.2^39 – 256 bits
), that's raughly64GB
. This also makes the security analysis of AES-GCM with long nonces complicated, since the hashed nonce doesn’t start with the lower 4 bytes set to 00 00 00 02. - ChaCha20-Poly1305: ChaCha has an internal counter (32 bits in the standardized IETF variant, 64 bits in the
original design). Max message lebgth is
2^39 - 256 bits
, about256 GB
- AES-GCM: Messages must be less than 2^32 – 2 blocks (a.k.a.
- Neither algorithm is nonce misuse resistant.
Conclusion: Both are good options. AES-GCM can be faster with hardware support, but pure-software implementations of ChaCha20-Poly1305 are almost always fast and constant-time.
- Safety on process kill (or crash): all writes to encrypted content is done in a tmp file and then using
mv
to move to destination. themv
operation is atomic as it's usingrename()
which is atomic as per specs, see hereThat specification requires that the action of the function be atomic.
- Phantom reads: reading older content from a file, this is not possible. While writing, data is kept in a buffer and
tmp file and on releasing the file handle we write the new content to the file (as per above the tmp file is moved
into place with
mv
). After that we reset all opened readers so any reads after that will pick up the new content
One problem that may occur is if we do a truncate we change the content of the file but the process is killed before we write the metadata with the new filesize. In this case next time we mount the system we are still seeing the old filesize but the content of the file could be bigger, and we read until the old size offset, se we would not pick up the new zeros bytes written on truncating by increasing the size. If content is smaller the read would stop and end-of-file of the actual content so this would not be such a big issue - What kind of metadata does it leak: close to none. The filename, actual file size and other file attrs (times,
permissions, other flags) are kept encrypted. What it could possible leak is the following
- If a directory has children we keep those children in a directory with name as inode number with encrypted names of children as files in it. So we could see how many children a directory has, but we can't identify that actual directory name, we can just see it's inode number (internal representation like an id for each file) and we cannot see the actual filenames of directory or children. Also we cannot identify which file content correspond to a directory child
- Each file content is saved in a separate file so we could see the size of the encrypted content, but not the actual filesize
- We can also see the last time the file was accessed
- It's always recommended to use encrypted disks for at least your sensitive data, this project is not a replacement for that
- In order to reduce the risk of encryption key to be exposed from memory it's recommended to disable mem dumps on the OS level. Please see here how to do it on Linux
- Cold boot attacks: in order to reduce the risk of this we keep the encryption key in memory just as long as we really need it to encrypt/decrypt data and we are zeroing it after that. We also remove it from memory after a period of inactivity
- Please note that this project is not audited by any security expert. It's built with security in mind and tries to follow all the best practices, but it's not guaranteed to be secure
- Also please backup your data, the project is still in development and there might be bugs that can lead to data loss
- Please note, this project doesn't try to reinvent the wheel or be better than already proven implementations
- This project doesn't want to be a replacement in any way of already proven file encryption solutions. If you really want close to bullet proof solutions than maybe this is not the ideal one for you. But is trying to offer a simple use of an ecryption solution that should be used taking into consideration all the security concerns from above
- It started as a learning project of Rust programming language and I feel like keep building more on it
- It's a fairly simple and standard implementation that tries to respect all security standards, use safe libs and ciphers in the implementation so that it can be extended from this. Indeed it doesn't have the maturity yet to "fight" other well known implementations but it can be a project from which others can learn or build upon or why not for some to actually use it keeping in mind all the above