use std::fmt::{self, Display}; use data_encoding::BASE64; use ed25519_dalek::SIGNATURE_LENGTH; use serde::{Deserialize, Serialize}; #[derive(Clone, Debug, Eq, PartialEq)] pub struct Signature<'a> { 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 { 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(SIGNATURE_LENGTH) { return Err(Error::InvalidSignatureLen(bytes64.len())); } let mut bytes = [0; SIGNATURE_LENGTH]; let mut buf = [0; SIGNATURE_LENGTH + 2]; match BASE64.decode_mut(bytes64.as_bytes(), &mut buf) { Ok(SIGNATURE_LENGTH) => bytes.copy_from_slice(&buf[..SIGNATURE_LENGTH]), Ok(_) => unreachable!(), // keeping DecodePartial gets annoying lifetime-wise Err(_) => return Err(Error::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() } } impl<'de: 'a, 'a> Deserialize<'de> for Signature<'a> { fn deserialize(deserializer: D) -> Result where D: serde::Deserializer<'de>, { let str: &'de str = Deserialize::deserialize(deserializer)?; Self::parse(str).map_err(|_| { serde::de::Error::invalid_value(serde::de::Unexpected::Str(str), &"Signature") }) } } impl<'a> Serialize for Signature<'a> { fn serialize(&self, serializer: S) -> Result where S: serde::Serializer, { let string: String = self.to_string(); string.serialize(serializer) } } #[derive(Debug, thiserror::Error)] pub enum Error { #[error("Invalid name: {0}")] InvalidName(String), #[error("Missing separator")] MissingSeparator, #[error("Invalid signature len: (expected {} b64-encoded, got {}", BASE64.encode_len(SIGNATURE_LENGTH), .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 hex_literal::hex; use lazy_static::lazy_static; use super::Signature; use rstest::rstest; 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"; // 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(); } #[rstest] #[case::valid_cache_nixos_org_1(&PUB_CACHE_NIXOS_ORG_1, &"cache.nixos.org-1:TsTTb3WGTZKphvYdBHXwo6weVILmTytUjLB+vcX89fOjjRicCHmKA4RCPMVLkj6TMJ4GMX3HPVWRdD1hkeKZBQ==", FINGERPRINT, true)] #[case::valid_test1(&PUB_CACHE_NIXOS_ORG_1, &"cache.nixos.org-1:TsTTb3WGTZKphvYdBHXwo6weVILmTytUjLB+vcX89fOjjRicCHmKA4RCPMVLkj6TMJ4GMX3HPVWRdD1hkeKZBQ==", FINGERPRINT, true)] #[case::valid_cache_nixos_org_different_name(&PUB_CACHE_NIXOS_ORG_1, &"cache.nixos.org-2:TsTTb3WGTZKphvYdBHXwo6weVILmTytUjLB+vcX89fOjjRicCHmKA4RCPMVLkj6TMJ4GMX3HPVWRdD1hkeKZBQ==", FINGERPRINT, true)] #[case::fail_invalid_cache_nixos_org_1_signature(&PUB_CACHE_NIXOS_ORG_1, &"cache.nixos.org-1:TsTTb000000000000000000000000ytUjLB+vcX89fOjjRicCHmKA4RCPMVLkj6TMJ4GMX3HPVWRdD1hkeKZBQ==", FINGERPRINT, false)] #[case::fail_valid_sig_but_wrong_fp_cache_nixos_org_1(&PUB_CACHE_NIXOS_ORG_1, &"cache.nixos.org-1:TsTTb3WGTZKphvYdBHXwo6weVILmTytUjLB+vcX89fOjjRicCHmKA4RCPMVLkj6TMJ4GMX3HPVWRdD1hkeKZBQ==", &FINGERPRINT[0..5], false)] fn verify_sigs( #[case] verifying_key: &VerifyingKey, #[case] sig_str: &'static str, #[case] fp: &str, #[case] expect_valid: bool, ) { let sig = Signature::parse(sig_str).expect("must parse"); assert_eq!(expect_valid, sig.verify(fp.as_bytes(), verifying_key)); } #[rstest] #[case::wrong_length("cache.nixos.org-1:o1DTsjCz0PofLJ216P2RBuSulI8BAb6zHxWE4N+tzlcELk5Uk/GO2SCxWTRN5wJutLZZ+cHTMdWqOHF8")] #[case::wrong_name_newline("test\n:u01BybwQhyI5H1bW1EIWXssMDhDDIvXOG5uh8Qzgdyjz6U1qg6DHhMAvXZOUStIj6X5t4/ufFgR8i3fjf0bMAw==")] #[case::wrong_name_space("test :u01BybwQhyI5H1bW1EIWXssMDhDDIvXOG5uh8Qzgdyjz6U1qg6DHhMAvXZOUStIj6X5t4/ufFgR8i3fjf0bMAw==")] #[case::empty_name( ":u01BybwQhyI5H1bW1EIWXssMDhDDIvXOG5uh8Qzgdyjz6U1qg6DHhMAvXZOUStIj6X5t4/ufFgR8i3fjf0bMAw==" )] #[case::b64_only( "u01BybwQhyI5H1bW1EIWXssMDhDDIvXOG5uh8Qzgdyjz6U1qg6DHhMAvXZOUStIj6X5t4/ufFgR8i3fjf0bMAw==" )] fn parse_fail(#[case] input: &'static str) { Signature::parse(input).expect_err("must fail"); } #[test] fn serialize_deserialize() { let signature_actual = Signature { name: "cache.nixos.org-1", bytes: hex!( r#"4e c4 d3 6f 75 86 4d 92 a9 86 f6 1d 04 75 f0 a3 ac 1e 54 82 e6 4f 2b 54 8c b0 7e bd c5 fc f5 f3 a3 8d 18 9c 08 79 8a 03 84 42 3c c5 4b 92 3e 93 30 9e 06 31 7d c7 3d 55 91 74 3d 61 91 e2 99 05"# ), }; let signature_str_json = "\"cache.nixos.org-1:TsTTb3WGTZKphvYdBHXwo6weVILmTytUjLB+vcX89fOjjRicCHmKA4RCPMVLkj6TMJ4GMX3HPVWRdD1hkeKZBQ==\""; let serialized = serde_json::to_string(&signature_actual).expect("must serialize"); assert_eq!(signature_str_json, &serialized); let deserialized: Signature<'_> = serde_json::from_str(signature_str_json).expect("must deserialize"); assert_eq!(&signature_actual, &deserialized); } }