File encryption done right

About

Kestrel is a data-at-rest file encryption program. Think PGP, but less unwieldy.

Kestrel makes it easy to encrypt files for yourself or friends.

Features and Advantages

• Encrypt files to anyone. Grab their public key or use a password.
• Quickly encrypt and decrypt files of any size.
• Strong security and privacy guarantees. Uses X25519, ChaCha20-Poly1305 and the Noise Protocol. Guarantees sender authentication.
• Keys are simple strings that are easy to manage and copy-paste.
• Private keys are always encrypted.
• Single binary that is easy to run anywhere.
• Supports Linux, macOS, Windows.
• BSDs will also likely work but are untested.

Disadvantages

• Does not handle signatures. You can't sign files with this. However, sender authentication is guaranteed.
• Does not solve the key distribution problem. You have to acquire known-good public keys through some other means.

Installation

Tested on Linux, macOS, Windows 10

Download files from the Official Site

Grab the GitHub release

If you have rust build tooling you can also use cargo install kestrel-cli

Contributing

Patches welcome. Please send feedback and bug reports for any issues that you may have.

License

BSD 3 Clause

Usage Examples

Generate a new private key kestrel key gen -o keyring.txt

Encrypt a file kestrel encrypt example.txt --to alice --from alice -k keyring.txt

Decrypt a file kestrel decrypt example.txt.ktl -t alice

Encrypt a file using a password kestrel pass enc example.txt

Set the environment variable KESTREL_KEYRING to use a default keyring file.

Usage

``` USAGE: kestrel encrypt FILE -t NAME -f NAME [-o FILE] [-k KEYRING] kestrel decrypt FILE -t NAME [-o FILE] [-k KEYRING] kestrel key generate -o FILE kestrel key change-pass PRIVATE-KEY kestrel key extract-pub PRIVATE-KEY kestrel password encrypt|decrypt FILE [-o FILE]

Aliases enc, dec, pass, and gen can be used as encrypt, decrypt,
password, and generate respectively.
Option -k is required unless KESTREL_KEYRING env var is set.

OPTIONS: -t, --to Recipient key name. Decrypt requires a private key. -f, --from Sender key name. Must be a private key. -o, --output Output file name. -k, --keyring Location of a keyring file. -h, --help Print help information. -v, --version Print version information. ```

Security Design Overview

The application uses a standard combination of the Noise Protocol and a chunked file encryption scheme.

The noise protocol (NoiseX25519ChaChaPolySHA256) is used to encrypt a payload key that is then used for ChaCha20-Poly1305 file encryption. Files are split into encrypted and authenticated chunks.

Users can also use a password instead of public keys. Scrypt is to derive a symmetric key for file encryption.

See more in the security documentation

Security Warning

To the best of my knowledge, Kestrel is secure. However, this software has not yet undergone a formal security audit. Swim at your own risk.