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//! This module defines data structures and parsers for the public key format
//! used inside Nix to verify signatures on .narinfo files.
use std::fmt::Display;
use data_encoding::BASE64;
use ed25519_dalek::{VerifyingKey, PUBLIC_KEY_LENGTH};
use super::Signature;
/// This represents a ed25519 public key and "name".
/// These are normally passed in the `trusted-public-keys` Nix config option,
/// and consist of a name and base64-encoded ed25519 pubkey, separated by a `:`.
#[derive(Debug)]
pub struct PubKey {
name: String,
verifying_key: VerifyingKey,
}
impl PubKey {
pub fn new(name: String, verifying_key: VerifyingKey) -> Self {
Self {
name,
verifying_key,
}
}
pub fn parse(input: &str) -> Result<Self, Error> {
let (name, bytes64) = input.split_once(':').ok_or(Error::MissingSeparator)?;
if name.is_empty()
|| !name
.chars()
.all(|c| char::is_alphanumeric(c) || c == '-' || c == '.')
{
return Err(Error::InvalidName(name.to_string()));
}
if bytes64.len() != BASE64.encode_len(PUBLIC_KEY_LENGTH) {
return Err(Error::InvalidPubKeyLen(bytes64.len()));
}
let mut buf = [0; PUBLIC_KEY_LENGTH + 1];
let mut bytes = [0; PUBLIC_KEY_LENGTH];
match BASE64.decode_mut(bytes64.as_bytes(), &mut buf) {
Ok(PUBLIC_KEY_LENGTH) => {
bytes.copy_from_slice(&buf[..PUBLIC_KEY_LENGTH]);
}
Ok(_) => unreachable!(),
// keeping DecodePartial gets annoying lifetime-wise
Err(_) => return Err(Error::DecodeError(input.to_string())),
}
let verifying_key = VerifyingKey::from_bytes(&bytes).map_err(Error::InvalidVerifyingKey)?;
Ok(Self {
name: name.to_string(),
verifying_key,
})
}
pub fn name(&self) -> &str {
&self.name
}
/// Verify the passed in signature is a correct signature for the passed in fingerprint and is signed
/// by the key material referred to by [Self],
/// which means the name in the signature has to match,
/// and the signature bytes themselves need to be a valid signature made by
/// the signing key identified by [Self::verifying key].
pub fn verify(&self, fingerprint: &str, signature: &Signature) -> bool {
if self.name() != signature.name() {
return false;
}
return signature.verify(fingerprint.as_bytes(), &self.verifying_key);
}
}
#[derive(Debug, thiserror::Error)]
pub enum Error {
#[error("Invalid name: {0}")]
InvalidName(String),
#[error("Missing separator")]
MissingSeparator,
#[error("Invalid pubkey len: {0}")]
InvalidPubKeyLen(usize),
#[error("VerifyingKey error: {0}")]
InvalidVerifyingKey(ed25519_dalek::SignatureError),
#[error("Unable to base64-decode pubkey: {0}")]
DecodeError(String),
}
impl Display for PubKey {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
write!(
f,
"{}:{}",
self.name,
BASE64.encode(self.verifying_key.as_bytes())
)
}
}
#[cfg(test)]
mod test {
use data_encoding::BASE64;
use ed25519_dalek::PUBLIC_KEY_LENGTH;
use rstest::rstest;
use crate::narinfo::Signature;
use super::PubKey;
const FINGERPRINT: &str = "1;/nix/store/syd87l2rxw8cbsxmxl853h0r6pdwhwjr-curl-7.82.0-bin;sha256:1b4sb93wp679q4zx9k1ignby1yna3z7c4c2ri3wphylbc2dwsys0;196040;/nix/store/0jqd0rlxzra1rs38rdxl43yh6rxchgc6-curl-7.82.0,/nix/store/6w8g7njm4mck5dmjxws0z1xnrxvl81xa-glibc-2.34-115,/nix/store/j5jxw3iy7bbz4a57fh9g2xm2gxmyal8h-zlib-1.2.12,/nix/store/yxvjs9drzsphm9pcf42a4byzj1kb9m7k-openssl-1.1.1n";
#[rstest]
#[case::cache_nixos_org("cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=", "cache.nixos.org-1", &BASE64.decode(b"6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=").unwrap()[..].try_into().unwrap())]
#[case::cache_nixos_org_different_name("cheesecake:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=", "cheesecake", &BASE64.decode(b"6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=").unwrap()[..].try_into().unwrap())]
#[case::test_1("test1:tLAEn+EeaBUJYqEpTd2yeerr7Ic6+0vWe+aXL/vYUpE=", "test1", &BASE64.decode(b"tLAEn+EeaBUJYqEpTd2yeerr7Ic6+0vWe+aXL/vYUpE=").unwrap()[..].try_into().unwrap())]
fn parse(
#[case] input: &'static str,
#[case] exp_name: &'static str,
#[case] exp_verifying_key_bytes: &[u8; PUBLIC_KEY_LENGTH],
) {
let pubkey = PubKey::parse(input).expect("must parse");
assert_eq!(exp_name, pubkey.name());
assert_eq!(exp_verifying_key_bytes, pubkey.verifying_key.as_bytes());
}
#[rstest]
#[case::empty_name("6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=")]
#[case::missing_padding("cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY")]
#[case::wrong_length("cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDS")]
fn parse_fail(#[case] input: &'static str) {
PubKey::parse(input).expect_err("must fail");
}
#[rstest]
#[case::correct_cache_nixos_org("cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=", FINGERPRINT, "cache.nixos.org-1:TsTTb3WGTZKphvYdBHXwo6weVILmTytUjLB+vcX89fOjjRicCHmKA4RCPMVLkj6TMJ4GMX3HPVWRdD1hkeKZBQ==", true)]
#[case::wrong_name_mismatch("cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=", FINGERPRINT, "cache.nixos.org:TsTTb3WGTZKphvYdBHXwo6weVILmTytUjLB+vcX89fOjjRicCHmKA4RCPMVLkj6TMJ4GMX3HPVWRdD1hkeKZBQ==", false)]
fn verify(
#[case] pubkey_str: &'static str,
#[case] fingerprint: &'static str,
#[case] signature_str: &'static str,
#[case] expected: bool,
) {
let pubkey = PubKey::parse(pubkey_str).expect("must parse");
let signature = Signature::parse(signature_str).expect("must parse");
assert_eq!(expected, pubkey.verify(fingerprint, &signature));
}
}
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