holographic_memory/core/provenance/
cose.rs

1// Copyright 2024-2026 WritersLogic Contributors
2// SPDX-License-Identifier: Apache-2.0
3
4use anyhow::{anyhow, Result};
5use coset::iana::Algorithm;
6use coset::{CborSerializable, CoseSign1, CoseSign1Builder, HeaderBuilder};
7use ed25519_dalek::{Signer, SigningKey, Verifier, VerifyingKey};
8
9/// Create a COSE Sign1 envelope over arbitrary payload bytes.
10pub fn sign_payload(signing_key: &SigningKey, payload: &[u8]) -> Result<Vec<u8>> {
11    let protected = HeaderBuilder::new()
12        .algorithm(Algorithm::EdDSA)
13        .key_id(signing_key.verifying_key().to_bytes().to_vec())
14        .build();
15
16    let sign1 = CoseSign1Builder::new()
17        .protected(protected)
18        .payload(payload.to_vec())
19        .create_signature(b"", |data| signing_key.sign(data).to_bytes().to_vec())
20        .build();
21
22    sign1
23        .to_vec()
24        .map_err(|e| anyhow!("COSE serialization failed: {e}"))
25}
26
27/// Verify a COSE Sign1 envelope and return the payload if valid.
28pub fn verify_and_extract(verifying_key: &VerifyingKey, cose_bytes: &[u8]) -> Result<Vec<u8>> {
29    let sign1 = CoseSign1::from_slice(cose_bytes)
30        .map_err(|e| anyhow!("COSE deserialization failed: {e}"))?;
31
32    let payload = sign1
33        .payload
34        .as_ref()
35        .ok_or_else(|| anyhow!("COSE envelope has no payload"))?;
36
37    sign1
38        .verify_signature(b"", |sig, data| {
39            let signature = ed25519_dalek::Signature::from_slice(sig)
40                .map_err(|e| anyhow!("invalid signature bytes: {e}"))?;
41            verifying_key
42                .verify(data, &signature)
43                .map_err(|e| anyhow!("signature verification failed: {e}"))
44        })
45        .map_err(|e| anyhow!("COSE verification failed: {e}"))?;
46
47    Ok(payload.clone())
48}
49
50/// Extract the key ID (verifying key bytes) from a COSE Sign1 envelope without verifying.
51pub fn extract_key_id(cose_bytes: &[u8]) -> Result<Vec<u8>> {
52    let sign1 = CoseSign1::from_slice(cose_bytes)
53        .map_err(|e| anyhow!("COSE deserialization failed: {e}"))?;
54    let kid = sign1.protected.header.key_id.clone();
55    if kid.is_empty() {
56        return Err(anyhow!("no key ID in COSE envelope"));
57    }
58    Ok(kid)
59}
60
61/// Build a COSE Sign1 envelope for a provenance claim about a fact.
62/// The payload is CBOR-encoded with fields: id, content_hash, source_uri, timestamp.
63pub fn sign_fact_claim(
64    signing_key: &SigningKey,
65    fact_id: &str,
66    content_hash: &[u8; 32],
67    source_uri: Option<&str>,
68    timestamp_ms: u64,
69) -> Result<Vec<u8>> {
70    let mut claim = ciborium::Value::Map(vec![
71        (
72            ciborium::Value::Text("id".to_string()),
73            ciborium::Value::Text(fact_id.to_string()),
74        ),
75        (
76            ciborium::Value::Text("content_hash".to_string()),
77            ciborium::Value::Bytes(content_hash.to_vec()),
78        ),
79        (
80            ciborium::Value::Text("timestamp_ms".to_string()),
81            ciborium::Value::Integer(timestamp_ms.into()),
82        ),
83    ]);
84    if let Some(uri) = source_uri {
85        if let ciborium::Value::Map(ref mut map) = claim {
86            map.push((
87                ciborium::Value::Text("source_uri".to_string()),
88                ciborium::Value::Text(uri.to_string()),
89            ));
90        }
91    }
92    let mut payload = Vec::new();
93    ciborium::into_writer(&claim, &mut payload)
94        .map_err(|e| anyhow!("CBOR encoding failed: {e}"))?;
95
96    sign_payload(signing_key, &payload)
97}
98
99#[cfg(test)]
100mod tests {
101    use super::*;
102
103    fn test_keypair() -> SigningKey {
104        SigningKey::from_bytes(&rand::random())
105    }
106
107    #[test]
108    fn sign_verify_roundtrip() {
109        let key = test_keypair();
110        let payload = b"test payload data";
111
112        let envelope = sign_payload(&key, payload).unwrap();
113        let recovered = verify_and_extract(&key.verifying_key(), &envelope).unwrap();
114        assert_eq!(recovered, payload);
115    }
116
117    #[test]
118    fn tampered_payload_rejected() {
119        let key = test_keypair();
120        let envelope = sign_payload(&key, b"original").unwrap();
121
122        let wrong_key = test_keypair();
123        assert!(verify_and_extract(&wrong_key.verifying_key(), &envelope).is_err());
124    }
125
126    #[test]
127    fn key_id_extraction() {
128        let key = test_keypair();
129        let envelope = sign_payload(&key, b"data").unwrap();
130        let kid = extract_key_id(&envelope).unwrap();
131        assert_eq!(kid, key.verifying_key().to_bytes().to_vec());
132    }
133
134    #[test]
135    fn fact_claim_roundtrip() {
136        let key = test_keypair();
137        let hash = [0xABu8; 32];
138        let envelope = sign_fact_claim(
139            &key,
140            "fact-001",
141            &hash,
142            Some("https://example.com"),
143            1719878400000,
144        )
145        .unwrap();
146        let payload = verify_and_extract(&key.verifying_key(), &envelope).unwrap();
147
148        let decoded: ciborium::Value = ciborium::from_reader(payload.as_slice()).unwrap();
149        if let ciborium::Value::Map(entries) = decoded {
150            let id_val = entries
151                .iter()
152                .find(|(k, _)| k == &ciborium::Value::Text("id".to_string()))
153                .unwrap();
154            assert_eq!(id_val.1, ciborium::Value::Text("fact-001".to_string()));
155        } else {
156            panic!("expected CBOR map");
157        }
158    }
159
160    fn unhex(s: &str) -> Vec<u8> {
161        (0..s.len())
162            .step_by(2)
163            .map(|i| u8::from_str_radix(&s[i..i + 2], 16).unwrap())
164            .collect()
165    }
166
167    #[test]
168    fn verifies_cogmem_cross_conformance_vector() {
169        // Cross-implementation conformance: a COSE_Sign1 EdDSA signed statement produced
170        // by cogmem (Python / cbor2). HMS must verify it and recover the payload, proving
171        // the two projects emit byte-compatible signed statements. See tests/vectors/.
172        let pk = unhex("4b5f52db17ebdeb555101922e89beac9b43e864086b02e4529951d7f491f0cfa");
173        let cose = unhex("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");
174        let expected = unhex("a6636973736c6469643a6b65793a74657374686d656d6f7279496468766563746f722d316a6d656d6f7279547970656472756c65656576656e7467637265617465646d73746174656d656e74486173685820000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f6b74696d657374616d704d731b0000019070bdb800");
175        let vk = VerifyingKey::from_bytes(&pk.try_into().unwrap()).unwrap();
176        let payload = verify_and_extract(&vk, &cose).unwrap();
177        assert_eq!(payload, expected);
178    }
179}
holographic_memory/core/provenance/cose.rs

holographic_memory/core/provenance/
cose.rs
