Module sequoia_guide::chapter_00

Describes how to create a simple Rust application using Sequoia.

Build dependencies

First of all, you need Rust, and a few libraries that we depend upon. On Debian-like systems, the required packages can be installed using the following command. As of this writing, this works fine on Debian 10 (Buster). You can use Debian 9 (Stretch), but you need to pull rustc, cargo, and nettle-dev from testing.

# apt install git rustc cargo clang make pkg-config nettle-dev libssl-dev capnproto libsqlite3-dev

Creating a new project

If are starting from scratch, you need to create a new crate:

$ cargo new --bin example
     Created binary (application) `example` project
$ cd example

Now add Sequoia to the [dependencies] section in Cargo.toml:

sequoia-openpgp = "*"

Note: Explicitly stating a major version for dependencies is usually better than just using the wildcard here (read how to specify dependencies). Also, please check that the crate's version matches the version of this guide.

If you want to use the bleeding edge, you can instead refer to the version in git:

sequoia-openpgp = { git = "https://gitlab.com/sequoia-pgp/sequoia.git" }

To build and run your application, do:

$ cargo run

On the first run, cargo will download and build Sequoia and all dependencies. When finished, nothing really happens because we have not populated main yet. Let's do that! Open src/main.rs with your favorite editor, and enter:

extern crate sequoia_openpgp as openpgp;
use std::io;
 
fn main() -> openpgp::Result<()> {
    let mut reader = openpgp::armor::Reader::from_bytes(
       b"-----BEGIN PGP ARMORED FILE-----
 
         SGVsbG8gd29ybGQhCg==
         =XLsG
         -----END PGP ARMORED FILE-----", None);
 
    io::copy(&mut reader, &mut io::stdout())?;
 
    Ok(())
}

Running the application now prints a friendly message to stdout.

A word on the armored macro. We will use this macro in this guide to inline OpenPGP data into the source code. Sequoia includes filters for ASCII armored data. You can use these filters to read armored data from any Reader, or write armored data to any Writer.

Building the Sequoia tool

Sequoia includes a simple frontend sq that can be used to experiment with Sequoia and OpenPGP. The documentation for this tool is here. It is also an example of how to use various aspects of Sequoia. Clone Sequoia and build the tool:

$ git clone https://gitlab.com/sequoia-pgp/sequoia.git
...
$ cd sequoia
$ cargo build -p sequoia-sq
...
$ target/debug/sq
sq 0.1.0
Sequoia is an implementation of OpenPGP.  This is a command-line frontend.
...