gpgrv

gpgrv is a Rust library for verifying some types of GPG signatures.

use std::io::{stdin, stdout, BufReader, Cursor, Seek, SeekFrom};
fn main() {
    // load a keyring from some file(s)
    // for example, we use the linux distribution keyring
    let mut keyring = gpgrv::Keyring::new();
    let keyring_file = Cursor::new(distro_keyring::supported_keys());
    keyring.append_keys_from(keyring_file).unwrap();

    // read stdin, verify, and write the output to a temporary file
    let mut temp = tempfile::tempfile().unwrap();
    gpgrv::verify_message(BufReader::new(stdin()), &mut temp, &keyring).expect("verification");

    // if we succeeded, print the temporary file to stdout
    temp.seek(SeekFrom::Start(0)).unwrap();
    std::io::copy(&mut temp, &mut stdout()).unwrap();
}

Supports

• Verifying signatures:
  • RSA
  • SHA1 and SHA2 (SHA-256, SHA-512).
• Signed "inline" messages, and detached signatures.
• Armoured and unarmoured/binary.
• Compression wrappers (added by gpg for most messages)
• Loading old-style keyrings (i.e. not keybox files)

Advantages

• Entirely safe Rust, no native code. Easy to build and portable.
• MIT (or Apache2, or whatever!) licensed, not LGPL.
• Simple, Rust-style API on streams (Read/Write).

Disadvantages

• A tiny amount of custom, low-risk crypto code. However, any crypto code can be wrong.
• Limited, but growing, support for key and data formats.
• (Intentionally) not constant time: Cannot be used for certain crypto applications. This is less important for signature verification with public keys.

Alternatives

• gpgme (LGPL) - bindings for native code, verbose API
• rpgp (MIT/Apache2) - serious implementation of plenty of pgp
• sequoia-openpgp (GPLv3) - serious implementation of plenty of pgp

I was using the the gpgme API, which works, but the API is painful, and the linking/requirements are complicated.

sequoia's license is wrong.

rpgp has too many features, although it does seem to be nicely split into crates.

Minimum Supported Rust Version (MSRV)

1.34.2 (Debian Stable 2019) is pinned in Travis. Much older currently works fine, but I don't plan to do extra work to make it happen. MSRV bumps are some kind of semver bump, to be decided for 1.0.0.

License

Licensed under either of

• Apache License, Version 2.0
• MIT license

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.