feat(core): normalize Ed25519 raw-key SPKI fingerprint to ed25519:hex (core/fingerprint-normalization)

crates/alknet-core/src/endpoint.rs

@@ -389,6 +389,9 @@ fn extract_quinn_client_fingerprint(connection: &quinn::Connection) -> Option<St
 
 #[cfg(any(feature = "quinn", feature = "iroh"))]
 fn fingerprint_from_cert_der(cert_der: &[u8]) -> Option<String> {
+    if let Some(raw_key) = extract_ed25519_raw_key_from_spki(cert_der) {
+        return Some(format!("ed25519:{}", hex::encode(raw_key)));
+    }
     use sha2::{Digest, Sha256};
     let mut hasher = Sha256::new();
     hasher.update(cert_der);
@@ -396,6 +399,114 @@ fn fingerprint_from_cert_der(cert_der: &[u8]) -> Option<String> {
     Some(format!("SHA256:{}", hex::encode(digest)))
 }
 
+/// `SubjectPublicKeyInfo ::= SEQUENCE { algorithm AlgorithmIdentifier, subjectPublicKey BIT STRING }`
+/// `AlgorithmIdentifier ::= SEQUENCE { algorithm OBJECT IDENTIFIER, parameters ANY OPTIONAL }`
+/// For Ed25519 the algorithm OID is `1.3.101.112` (DER bytes `2b 65 70`), with no parameters,
+/// and `subjectPublicKey` is a BIT STRING containing one unused-bits byte (`0x00`) followed
+/// by the 32-byte raw Ed25519 public key. Returns the 32 raw key bytes when `cert_der` is an
+/// RFC 7250 raw public key (SPKI) with the Ed25519 algorithm identifier; returns `None`
+/// otherwise (X.509 cert, non-Ed25519 SPKI, or malformed DER), in which case callers should
+/// fall back to hashing the full DER.
+#[cfg(any(feature = "quinn", feature = "iroh"))]
+fn extract_ed25519_raw_key_from_spki(cert_der: &[u8]) -> Option<[u8; 32]> {
+    const ED25519_OID_BYTES: [u8; 3] = [0x2b, 0x65, 0x70];
+
+    let mut parser = DerParser::new(cert_der);
+    let spki_contents = parser.expect_sequence()?;
+    let mut spki_parser = DerParser::new(spki_contents);
+
+    let alg_id_contents = spki_parser.expect_sequence()?;
+    let mut alg_id_parser = DerParser::new(alg_id_contents);
+    let oid_bytes = alg_id_parser.expect_oid()?;
+    if oid_bytes != ED25519_OID_BYTES {
+        return None;
+    }
+
+    let bit_string_contents = spki_parser.expect_bit_string()?;
+    if bit_string_contents.len() != 33 || bit_string_contents[0] != 0x00 {
+        return None;
+    }
+    let mut raw_key = [0u8; 32];
+    raw_key.copy_from_slice(&bit_string_contents[1..33]);
+    Some(raw_key)
+}
+
+#[cfg(any(feature = "quinn", feature = "iroh"))]
+struct DerParser<'a> {
+    bytes: &'a [u8],
+}
+
+#[cfg(any(feature = "quinn", feature = "iroh"))]
+impl<'a> DerParser<'a> {
+    fn new(bytes: &'a [u8]) -> Self {
+        Self { bytes }
+    }
+
+    fn read_tlv(&mut self) -> Option<(u8, &'a [u8])> {
+        let (tag, len_size, header_len) = self.decode_header()?;
+        let total = header_len.checked_add(len_size)?;
+        if total > self.bytes.len() {
+            return None;
+        }
+        let content = &self.bytes[header_len..total];
+        self.bytes = &self.bytes[total..];
+        Some((tag, content))
+    }
+
+    fn decode_header(&self) -> Option<(u8, usize, usize)> {
+        if self.bytes.is_empty() {
+            return None;
+        }
+        let tag = self.bytes[0];
+        if self.bytes.len() < 2 {
+            return None;
+        }
+        let first_len = self.bytes[1];
+        if first_len < 0x80 {
+            return Some((tag, first_len as usize, 2));
+        }
+        let num_bytes = (first_len & 0x7f) as usize;
+        if num_bytes == 0 || num_bytes > 4 {
+            return None;
+        }
+        if self.bytes.len() < 2 + num_bytes {
+            return None;
+        }
+        let mut len: usize = 0;
+        for i in 0..num_bytes {
+            len = (len << 8) | (self.bytes[2 + i] as usize);
+        }
+        Some((tag, len, 2 + num_bytes))
+    }
+
+    fn expect_sequence(&mut self) -> Option<&'a [u8]> {
+        let (tag, content) = self.read_tlv()?;
+        if tag == 0x30 {
+            Some(content)
+        } else {
+            None
+        }
+    }
+
+    fn expect_oid(&mut self) -> Option<&'a [u8]> {
+        let (tag, content) = self.read_tlv()?;
+        if tag == 0x06 {
+            Some(content)
+        } else {
+            None
+        }
+    }
+
+    fn expect_bit_string(&mut self) -> Option<&'a [u8]> {
+        let (tag, content) = self.read_tlv()?;
+        if tag == 0x03 {
+            Some(content)
+        } else {
+            None
+        }
+    }
+}
+
 #[cfg(feature = "iroh")]
 async fn run_iroh_accept_loop(
     iroh: iroh::Endpoint,
@@ -1297,6 +1408,102 @@ mod tests {
         assert_eq!(a, b, "same cert DER must produce same fingerprint");
     }
 
+    #[cfg(any(feature = "quinn", feature = "iroh"))]
+    fn build_ed25519_spki_der(raw_key: &[u8; 32]) -> Vec<u8> {
+        use rustls::pki_types::alg_id;
+        let spki = rustls::sign::public_key_to_spki(&alg_id::ED25519, raw_key);
+        spki.to_vec()
+    }
+
+    #[cfg(any(feature = "quinn", feature = "iroh"))]
+    #[test]
+    fn fingerprint_from_ed25519_spki_produces_ed25519_prefix() {
+        let sk = crate::config::Ed25519SecretKey::generate();
+        let raw_key = sk.public().to_bytes();
+        let spki_der = build_ed25519_spki_der(&raw_key);
+        let fp = fingerprint_from_cert_der(&spki_der).expect("spki produces fingerprint");
+        assert!(
+            fp.starts_with("ed25519:"),
+            "Ed25519 raw key SPKI must produce ed25519: fingerprint, got: {fp}"
+        );
+    }
+
+    #[cfg(any(feature = "quinn", feature = "iroh"))]
+    #[test]
+    fn fingerprint_from_ed25519_spki_is_lowercase_hex_of_32_byte_key() {
+        let sk = crate::config::Ed25519SecretKey::generate();
+        let raw_key = sk.public().to_bytes();
+        let spki_der = build_ed25519_spki_der(&raw_key);
+        let fp = fingerprint_from_cert_der(&spki_der).expect("spki produces fingerprint");
+        let hex_part = &fp["ed25519:".len()..];
+        assert_eq!(
+            hex_part.len(),
+            64,
+            "ed25519 hex part must be 64 chars (32 bytes), got: {fp}"
+        );
+        assert!(
+            hex_part
+                .chars()
+                .all(|c| c.is_ascii_hexdigit() && !c.is_ascii_uppercase()),
+            "ed25519 hex part must be lowercase hex, got: {fp}"
+        );
+        assert_eq!(
+            hex_part,
+            hex::encode(raw_key),
+            "ed25519 fingerprint must be hex of the raw 32-byte key, not the DER wrapper"
+        );
+    }
+
+    #[cfg(any(feature = "quinn", feature = "iroh"))]
+    #[test]
+    fn fingerprint_from_ed25519_spki_matches_iroh_format() {
+        let sk = crate::config::Ed25519SecretKey::generate();
+        let raw_key = sk.public().to_bytes();
+        let spki_der = build_ed25519_spki_der(&raw_key);
+        let quinn_fp = fingerprint_from_cert_der(&spki_der).expect("spki produces fingerprint");
+        let iroh_fp = format!("ed25519:{}", hex::encode(raw_key));
+        assert_eq!(
+            quinn_fp, iroh_fp,
+            "same Ed25519 key must produce the same fingerprint via quinn SPKI and iroh NodeId paths"
+        );
+    }
+
+    #[cfg(any(feature = "quinn", feature = "iroh"))]
+    #[test]
+    fn fingerprint_from_x509_cert_stays_sha256_of_der() {
+        let cert_der = b"fake-x509-cert-der-bytes-not-an-spki";
+        let fp = fingerprint_from_cert_der(cert_der).expect("x509 produces fingerprint");
+        assert!(
+            fp.starts_with("SHA256:"),
+            "X.509 cert must keep SHA256: format, got: {fp}"
+        );
+        use sha2::{Digest, Sha256};
+        let mut hasher = Sha256::new();
+        hasher.update(cert_der);
+        assert_eq!(
+            fp,
+            format!("SHA256:{}", hex::encode(hasher.finalize())),
+            "X.509 fingerprint must be SHA-256 of cert DER"
+        );
+    }
+
+    #[cfg(any(feature = "quinn", feature = "iroh"))]
+    #[test]
+    fn fingerprint_from_non_ed25519_spki_falls_back_to_sha256() {
+        let raw_key = [0u8; 32];
+        let fake_non_ed25519_spki: Vec<u8> = vec![
+            0x30, 0x1c, 0x30, 0x05, 0x06, 0x03, 0x2b, 0x06, 0x01, 0x03, 0x15, 0x00, 0x20,
+        ]
+        .into_iter()
+        .chain(raw_key.iter().copied())
+        .collect();
+        let fp = fingerprint_from_cert_der(&fake_non_ed25519_spki).expect("fallback fingerprint");
+        assert!(
+            fp.starts_with("SHA256:"),
+            "non-Ed25519 SPKI must fall back to SHA256:, got: {fp}"
+        );
+    }
+
     #[test]
     fn acme_directory_production_url() {
         use crate::config::AcmeDirectory;

crates/alknet-vault/src/protocol.rs

@@ -178,10 +178,10 @@ mod tests {
         let key = make_test_key();
         let public = serde_json::to_string(&key.public_key).unwrap();
         let private = serde_json::to_string(&vec![0xABu8; 32]).unwrap();
-        let json = format!(
-            r#"{{"key_type":"Ed25519","private_key":{private},"public_key":{public}}}"#
-        );
-        let result: DerivedKey = serde_json::from_str(&json).expect("non-redacted payload deserializes");
+        let json =
+            format!(r#"{{"key_type":"Ed25519","private_key":{private},"public_key":{public}}}"#);
+        let result: DerivedKey =
+            serde_json::from_str(&json).expect("non-redacted payload deserializes");
         assert_eq!(result.key_type, KeyType::Ed25519);
         assert_eq!(result.private_key, vec![0xABu8; 32]);
         assert_eq!(result.public_key, key.public_key);