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use std::fmt::{self, Display};
use data_encoding::BASE64;
use ed25519_dalek::SIGNATURE_LENGTH;
#[derive(Debug)]
pub struct Signature<'a> {
/// TODO(edef): be stricter with signature names here, they especially shouldn't have newlines!
name: &'a str,
bytes: [u8; SIGNATURE_LENGTH],
}
impl<'a> Signature<'a> {
pub fn new(name: &'a str, bytes: [u8; SIGNATURE_LENGTH]) -> Self {
Self { name, bytes }
}
pub fn parse(input: &'a str) -> Result<Self, SignatureError> {
let (name, bytes64) = input
.split_once(':')
.ok_or(SignatureError::MissingSeparator)?;
let mut buf = [0; SIGNATURE_LENGTH + 2];
let mut bytes = [0; SIGNATURE_LENGTH];
match BASE64.decode_mut(bytes64.as_bytes(), &mut buf) {
Ok(SIGNATURE_LENGTH) => {
bytes.copy_from_slice(&buf[..SIGNATURE_LENGTH]);
}
Ok(n) => return Err(SignatureError::InvalidSignatureLen(n)),
// keeping DecodePartial gets annoying lifetime-wise
Err(_) => return Err(SignatureError::DecodeError(input.to_string())),
}
Ok(Signature { name, bytes })
}
pub fn name(&self) -> &'a str {
self.name
}
pub fn bytes(&self) -> &[u8; SIGNATURE_LENGTH] {
&self.bytes
}
/// For a given fingerprint and ed25519 verifying key, ensure if the signature is valid.
pub fn verify(&self, fingerprint: &[u8], verifying_key: &ed25519_dalek::VerifyingKey) -> bool {
let signature = ed25519_dalek::Signature::from_bytes(self.bytes());
verifying_key.verify_strict(fingerprint, &signature).is_ok()
}
}
#[derive(Debug, thiserror::Error)]
pub enum SignatureError {
#[error("Missing separator")]
MissingSeparator,
#[error("Invalid signature len: {0}")]
InvalidSignatureLen(usize),
#[error("Unable to base64-decode signature: {0}")]
DecodeError(String),
}
impl Display for Signature<'_> {
fn fmt(&self, w: &mut fmt::Formatter) -> fmt::Result {
write!(w, "{}:{}", self.name, BASE64.encode(&self.bytes))
}
}
#[cfg(test)]
mod test {
use data_encoding::BASE64;
use ed25519_dalek::VerifyingKey;
use lazy_static::lazy_static;
use super::Signature;
use test_case::test_case;
const FINGERPRINT: &'static 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";
// The signing key labelled as `cache.nixos.org-1`,
lazy_static! {
static ref PUB_CACHE_NIXOS_ORG_1: VerifyingKey = ed25519_dalek::VerifyingKey::from_bytes(
BASE64
.decode(b"6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=")
.unwrap()[..]
.try_into()
.unwrap()
)
.unwrap();
static ref PUB_TEST_1: VerifyingKey = ed25519_dalek::VerifyingKey::from_bytes(
BASE64
.decode(b"tLAEn+EeaBUJYqEpTd2yeerr7Ic6+0vWe+aXL/vYUpE=")
.unwrap()[..]
.try_into()
.unwrap()
)
.unwrap();
}
#[test_case(&PUB_CACHE_NIXOS_ORG_1, &"cache.nixos.org-1:TsTTb3WGTZKphvYdBHXwo6weVILmTytUjLB+vcX89fOjjRicCHmKA4RCPMVLkj6TMJ4GMX3HPVWRdD1hkeKZBQ==", FINGERPRINT, true; "valid cache.nixos.org-1")]
#[test_case(&PUB_CACHE_NIXOS_ORG_1, &"cache.nixos.org-1:TsTTb3WGTZKphvYdBHXwo6weVILmTytUjLB+vcX89fOjjRicCHmKA4RCPMVLkj6TMJ4GMX3HPVWRdD1hkeKZBQ==", FINGERPRINT, true; "valid test1")]
#[test_case(&PUB_CACHE_NIXOS_ORG_1, &"cache.nixos.org-2:TsTTb3WGTZKphvYdBHXwo6weVILmTytUjLB+vcX89fOjjRicCHmKA4RCPMVLkj6TMJ4GMX3HPVWRdD1hkeKZBQ==", FINGERPRINT, true; "valid cache.nixos.org different name")]
#[test_case(&PUB_CACHE_NIXOS_ORG_1, &"cache.nixos.org-1:TsTTb000000000000000000000000ytUjLB+vcX89fOjjRicCHmKA4RCPMVLkj6TMJ4GMX3HPVWRdD1hkeKZBQ==", FINGERPRINT, false; "fail invalid cache.nixos.org-1 signature")]
#[test_case(&PUB_CACHE_NIXOS_ORG_1, &"cache.nixos.org-1:TsTTb3WGTZKphvYdBHXwo6weVILmTytUjLB+vcX89fOjjRicCHmKA4RCPMVLkj6TMJ4GMX3HPVWRdD1hkeKZBQ==", &FINGERPRINT[0..5], false; "fail valid sig but wrong fp cache.nixos.org-1")]
fn verify_sigs(
verifying_key: &VerifyingKey,
sig_str: &'static str,
fp: &str,
expect_valid: bool,
) {
let sig = Signature::parse(sig_str).expect("must parse");
assert_eq!(expect_valid, sig.verify(fp.as_bytes(), verifying_key));
}
}
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