tor-cert

Implementation for Tor certificates

Overview

The tor-cert crate implements the binary certificate types documented in Tor's cert-spec.txt, which are used when authenticating Tor channels. (Eventually, support for onion service certificate support will get added too.)

This crate is part of Arti, a project to implement Tor in Rust.

There are other types of certificate used by Tor as well, and they are implemented in other places. In particular, see [tor-netdoc::doc::authcert] for the certificate types used by authorities in the directory protocol.

Design notes

The tor-cert code is in its own separate crate because it is required by several other higher-level crates that do not depend upon each other. For example, [tor-netdoc] parses encoded certificates from router descriptors, while [tor-proto] uses certificates when authenticating relays.

Examples

Parsing, validating, and inspecting a certificate:

use base64ct::{Base64, Encoding as _};
use tor_cert::*;
use tor_checkable::*;
// Taken from a random relay on the Tor network.
let cert_base64 =
 "AQQABrntAThPWJ4nFH1L77Ar+emd4GPXZTPUYzIwmR2H6Zod5TvXAQAgBAC+vzqh
  VFO1SGATubxcrZzrsNr+8hrsdZtyGg/Dde/TqaY1FNbeMqtAPMziWOd6txzShER4
  qc/haDk5V45Qfk6kjcKw+k7cPwyJeu+UF/azdoqcszHRnUHRXpiPzudPoA4=";
// Remove the whitespace, so base64 doesn't choke on it.
let cert_base64: String = cert_base64.split_whitespace().collect();
// Decode the base64.
let cert_bin = Base64::decode_vec(&cert_base64).unwrap();

// Decode the cert and check its signature.
let cert = Ed25519Cert::decode(&cert_bin).unwrap()
    .check_key(None).unwrap()
    .check_signature().unwrap()
    .dangerously_assume_timely();
let signed_key = cert.subject_key();

License: MIT OR Apache-2.0