gpgrv

An RV.

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

use std::io::{stdin, stdout, BufReader, Seek, SeekFrom};
use buffered_reader::BufferedReaderGeneric as BufReadGeneric;
fn check_stdin(keyring: &gpgrv::Keyring) {
    let mut temp = tempfile::tempfile().unwrap();
    gpgrv::verify_message(BufReadGeneric::new(stdin(), None), &mut temp, keyring)
        .expect("verification");
    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.

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.