molpha_verifier/
verify.rs

1//! High-level attestation verification over caller-supplied signer pubkeys.
2//!
3//! These functions are pure: the caller resolves the signer pubkeys (e.g. from an on-chain
4//! registry, an off-chain snapshot, or hard-coded constants) and passes them in. No anchor,
5//! no `AccountInfo`, no PDA reads.
6
7use solana_secp256k1_recover::secp256k1_recover;
8
9use crate::bitmap::{bitmap_is_subset_u256, bitmap_load};
10use crate::coalition::CoalitionAccumulator;
11use crate::error::AttestationError;
12use crate::message::compute_message_hash;
13use crate::payload::{Attestation, AttestationPayload, SchnorrSignature};
14use crate::scalar::{
15    eth_address_from_uncompressed_pubkey, evm_schnorr_ecdsa_inputs,
16    secp256k1_scalar_is_valid_nonzero,
17};
18use crate::selection::derive_selection_bitmap;
19
20/// Stored secp256k1 affine coordinates `(x, y)`, big-endian — as kept in a `Node`.
21pub type SignerXy = ([u8; 32], [u8; 32]);
22
23/// Verify an attestation against caller-supplied signer pubkeys.
24///
25/// # Caller contract
26/// - `node_count` is the registry node count for `attestation.payload.registry_version`.
27/// - `ordered_signers` holds one `(x, y)` per set bit of `attestation.signature.signers_bitmap`,
28///   in **ascending bit-index order** — the same order EVM `Validator.verify` combines pubkeys.
29///   The caller is responsible for resolving the authentic pubkeys; this function trusts the
30///   supplied set.
31///
32/// Re-derives the selection bitmap internally and enforces `signers ⊆ selection`. Checks run in the
33/// same order as the on-chain monolith: scalar validity → signer threshold → selection subset →
34/// signer-count match → coalition reconstruction → message hash → Schnorr recovery.
35pub fn verify_attestation(
36    attestation: &Attestation,
37    node_count: u32,
38    redundancy_buffer: u8,
39    ordered_signers: &[SignerXy],
40) -> Result<(), AttestationError> {
41    verify_attestation_parts(
42        &attestation.payload,
43        &attestation.signature,
44        node_count,
45        redundancy_buffer,
46        ordered_signers,
47    )
48}
49
50/// Like [`verify_attestation`] but taking compressed (33-byte) signer pubkeys.
51pub fn verify_attestation_compressed(
52    attestation: &Attestation,
53    node_count: u32,
54    redundancy_buffer: u8,
55    ordered_signers_compressed: &[[u8; 33]],
56) -> Result<(), AttestationError> {
57    let xy = decompress_all(ordered_signers_compressed)?;
58    verify_attestation_parts(
59        &attestation.payload,
60        &attestation.signature,
61        node_count,
62        redundancy_buffer,
63        &xy,
64    )
65}
66
67pub(crate) fn verify_attestation_parts(
68    payload: &AttestationPayload,
69    signature: &SchnorrSignature,
70    node_count: u32,
71    redundancy_buffer: u8,
72    ordered_signers: &[SignerXy],
73) -> Result<(), AttestationError> {
74    if signature.agg_sig_s == [0u8; 32] || !secp256k1_scalar_is_valid_nonzero(&signature.agg_sig_s)
75    {
76        return Err(AttestationError::InvalidAggregateSignature);
77    }
78
79    let signers = bitmap_load(&signature.signers_bitmap);
80    let signer_count = signers.count_ones();
81    if signer_count < u32::from(payload.signatures_required) {
82        return Err(AttestationError::InsufficientSigners);
83    }
84
85    let expected_selection = derive_selection_bitmap(
86        &payload.source_id,
87        payload.registry_version,
88        payload.canonical_timestamp,
89        node_count,
90        payload.signatures_required,
91        redundancy_buffer,
92    )?;
93    if !bitmap_is_subset_u256(signers, bitmap_load(&expected_selection)) {
94        return Err(AttestationError::SignersNotSubsetOfSelection);
95    }
96
97    if ordered_signers.len() != signer_count as usize {
98        return Err(AttestationError::SignerCountMismatch);
99    }
100
101    let x_coalition = reconstruct_coalition_key(ordered_signers)?;
102    let message_hash = compute_message_hash(payload, signature.signers_bitmap);
103
104    if recover_and_match(
105        &x_coalition,
106        &message_hash,
107        &signature.agg_sig_s,
108        &signature.commitment_addr,
109    ) {
110        Ok(())
111    } else {
112        Err(AttestationError::InvalidAggregateSignature)
113    }
114}
115
116/// Reconstruct the coalition key `Σ X_i` from ordered signer pubkeys → compressed (33 bytes).
117///
118/// Errors on an empty signer set or a point-at-infinity sum.
119pub fn reconstruct_coalition_key(
120    ordered_signers: &[SignerXy],
121) -> Result<[u8; 33], AttestationError> {
122    if ordered_signers.is_empty() {
123        return Err(AttestationError::InvalidSignersBitmap);
124    }
125    let mut coalition = CoalitionAccumulator::default();
126    for (x, y) in ordered_signers {
127        coalition.add_stored_xy(x, y)?;
128    }
129    coalition.compressed_pubkey()
130}
131
132/// Compressed-pubkey variant of [`reconstruct_coalition_key`].
133pub fn reconstruct_coalition_key_compressed(
134    ordered_signers_compressed: &[[u8; 33]],
135) -> Result<[u8; 33], AttestationError> {
136    let xy = decompress_all(ordered_signers_compressed)?;
137    reconstruct_coalition_key(&xy)
138}
139
140/// Verify the aggregate Schnorr signature over an arbitrary `message_hash` against the coalition
141/// formed by `ordered_signers`.
142///
143/// Returns `Ok(true)` when valid (no fraud), `Ok(false)` when invalid (fabricated / committed
144/// garbage → slashable). `Err` only on malformed input (empty signer set, bad curve point). This
145/// mirrors the dispute-path semantics in the Molpha program.
146pub fn verify_aggregate_over_hash(
147    ordered_signers: &[SignerXy],
148    agg_sig_s: &[u8; 32],
149    commitment_addr: &[u8; 20],
150    message_hash: &[u8; 32],
151) -> Result<bool, AttestationError> {
152    if !secp256k1_scalar_is_valid_nonzero(agg_sig_s) {
153        return Ok(false);
154    }
155    let x_coalition = reconstruct_coalition_key(ordered_signers)?;
156    Ok(recover_and_match(
157        &x_coalition,
158        message_hash,
159        agg_sig_s,
160        commitment_addr,
161    ))
162}
163
164/// Run the Schnorr→ECDSA recovery trick and compare the recovered address to `commitment_addr`.
165fn recover_and_match(
166    x_coalition: &[u8; 33],
167    message_hash: &[u8; 32],
168    agg_sig_s: &[u8; 32],
169    commitment_addr: &[u8; 20],
170) -> bool {
171    let (recovery_id, ecdsa_signature, ecdsa_hash) =
172        match evm_schnorr_ecdsa_inputs(x_coalition, message_hash, agg_sig_s, commitment_addr) {
173            Ok(v) => v,
174            Err(_) => return false,
175        };
176    let recovered = match secp256k1_recover(&ecdsa_hash, recovery_id, &ecdsa_signature) {
177        Ok(r) => r,
178        Err(_) => return false,
179    };
180    eth_address_from_uncompressed_pubkey(recovered.to_bytes()) == *commitment_addr
181}
182
183fn decompress_all(compressed: &[[u8; 33]]) -> Result<Vec<SignerXy>, AttestationError> {
184    use libsecp256k1::{PublicKey, PublicKeyFormat};
185    compressed
186        .iter()
187        .map(|c| {
188            let pk = PublicKey::parse_slice(c, Some(PublicKeyFormat::Compressed))
189                .map_err(|_| AttestationError::InvalidAggregateSignature)?;
190            let full = pk.serialize(); // 0x04 || x || y
191            let x: [u8; 32] = full[1..33].try_into().unwrap();
192            let y: [u8; 32] = full[33..65].try_into().unwrap();
193            Ok((x, y))
194        })
195        .collect()
196}
197
198#[cfg(test)]
199mod tests {
200    use super::*;
201    use crate::fixtures::{
202        CANONICAL_TIMESTAMP, COMMITMENT, PUBKEYS, REDUNDANCY_BUFFER, REGISTERED_NODE_COUNT,
203        REGISTRY_VERSION, S, SIGNATURES_REQUIRED, SIGNERS_BITMAP, SIGNER_COUNT, SOURCE_ID, VALUE,
204    };
205    use crate::message::MESSAGE_PREFIX;
206    use libsecp256k1::{PublicKey, PublicKeyFormat};
207
208    fn fixture_payload() -> AttestationPayload {
209        AttestationPayload {
210            value: VALUE,
211            source_id: SOURCE_ID,
212            registry_version: REGISTRY_VERSION,
213            canonical_timestamp: CANONICAL_TIMESTAMP,
214            signatures_required: SIGNATURES_REQUIRED,
215        }
216    }
217
218    fn fixture_signature() -> SchnorrSignature {
219        SchnorrSignature {
220            agg_sig_s: S,
221            commitment_addr: COMMITMENT,
222            signers_bitmap: SIGNERS_BITMAP,
223        }
224    }
225
226    fn fixture_signers_xy() -> Vec<SignerXy> {
227        use crate::bitmap::for_each_set_bit;
228        let mut signers = Vec::new();
229        for_each_set_bit(&SIGNERS_BITMAP, |i| {
230            let c = &PUBKEYS[i];
231            let pk = PublicKey::parse_slice(c, Some(PublicKeyFormat::Compressed))
232                .expect("fixture pubkey must be a valid curve point");
233            let full = pk.serialize();
234            let x: [u8; 32] = full[1..33].try_into().unwrap();
235            let y: [u8; 32] = full[33..65].try_into().unwrap();
236            signers.push((x, y));
237        });
238        signers
239    }
240
241    fn fixture_signer_pubkeys_compressed() -> Vec<[u8; 33]> {
242        use crate::bitmap::for_each_set_bit;
243        let mut signers = Vec::new();
244        for_each_set_bit(&SIGNERS_BITMAP, |i| {
245            signers.push(PUBKEYS[i]);
246        });
247        signers
248    }
249
250    #[test]
251    fn fixture_pubkeys_are_valid_curve_points() {
252        for (i, pk) in PUBKEYS.iter().enumerate() {
253            PublicKey::parse_slice(pk, Some(PublicKeyFormat::Compressed))
254                .unwrap_or_else(|_| panic!("fixture pubkey {i} is not a valid curve point"));
255        }
256    }
257
258    #[test]
259    fn fixture_signers_bitmap_popcount_meets_threshold() {
260        use crate::bitmap::bitmap_popcount_evm;
261        let popcount = bitmap_popcount_evm(&SIGNERS_BITMAP);
262        assert_eq!(popcount, SIGNER_COUNT);
263        assert!(popcount >= u32::from(SIGNATURES_REQUIRED));
264    }
265
266    /// The coalition-from-pubkeys path must match `PublicKey::combine`.
267    #[test]
268    fn reconstruct_coalition_key_matches_combine() {
269        let signer_pubkeys = fixture_signer_pubkeys_compressed();
270        let pks: Vec<PublicKey> = signer_pubkeys
271            .iter()
272            .map(|c| PublicKey::parse_slice(c, Some(PublicKeyFormat::Compressed)).unwrap())
273            .collect();
274        let combined = PublicKey::combine(&pks).unwrap().serialize_compressed();
275        let got = reconstruct_coalition_key(&fixture_signers_xy()).unwrap();
276        assert_eq!(got, combined);
277        let got_c = reconstruct_coalition_key_compressed(&signer_pubkeys).unwrap();
278        assert_eq!(got_c, combined);
279    }
280
281    fn fixture_attestation() -> Attestation {
282        Attestation {
283            payload: fixture_payload(),
284            signature: fixture_signature(),
285        }
286    }
287
288    /// Full end-to-end EVM-compat verification with caller-supplied pubkeys — no anchor, no PDAs.
289    #[test]
290    fn verify_attestation_accepts_evm_fixture() {
291        let attestation = fixture_attestation();
292        let signer_pubkeys = fixture_signer_pubkeys_compressed();
293        verify_attestation(
294            &attestation,
295            REGISTERED_NODE_COUNT,
296            REDUNDANCY_BUFFER,
297            &fixture_signers_xy(),
298        )
299        .expect("fixture attestation must verify");
300        verify_attestation_compressed(
301            &attestation,
302            REGISTERED_NODE_COUNT,
303            REDUNDANCY_BUFFER,
304            &signer_pubkeys,
305        )
306        .expect("compressed variant must verify");
307    }
308
309    #[test]
310    fn tampered_s_fails_verification() {
311        let mut attestation = fixture_attestation();
312        attestation.signature.agg_sig_s[31] ^= 0x01;
313        let res = verify_attestation(
314            &attestation,
315            REGISTERED_NODE_COUNT,
316            REDUNDANCY_BUFFER,
317            &fixture_signers_xy(),
318        );
319        assert_eq!(res, Err(AttestationError::InvalidAggregateSignature));
320    }
321
322    #[test]
323    fn wrong_signer_count_is_rejected() {
324        let attestation = fixture_attestation();
325        let mut signers = fixture_signers_xy();
326        signers.pop();
327        assert_eq!(
328            verify_attestation(
329                &attestation,
330                REGISTERED_NODE_COUNT,
331                REDUNDANCY_BUFFER,
332                &signers,
333            ),
334            Err(AttestationError::SignerCountMismatch)
335        );
336    }
337
338    #[test]
339    fn verify_aggregate_over_hash_roundtrip() {
340        let payload = fixture_payload();
341        let signature = fixture_signature();
342        let signers = fixture_signers_xy();
343        let message_hash = compute_message_hash(&payload, signature.signers_bitmap);
344        assert!(verify_aggregate_over_hash(
345            &signers,
346            &signature.agg_sig_s,
347            &signature.commitment_addr,
348            &message_hash,
349        )
350        .unwrap());
351
352        // Tampered hash → invalid (slashable), not an error.
353        let mut bad_hash = message_hash;
354        bad_hash[0] ^= 0xff;
355        assert!(!verify_aggregate_over_hash(
356            &signers,
357            &signature.agg_sig_s,
358            &signature.commitment_addr,
359            &bad_hash,
360        )
361        .unwrap());
362    }
363
364    #[test]
365    fn message_prefix_matches_known_constant() {
366        // Guard against accidental edits to the domain-separation prefix.
367        assert_eq!(MESSAGE_PREFIX[0], 0xa7);
368    }
369}
molpha_verifier/verify.rs

molpha_verifier/
verify.rs
