Complete attestation_validation, bar tests

beacon_chain/attestation_validation/src/signature.rs

@@ -0,0 +1,149 @@
+use super::bls::{AggregatePublicKey, AggregateSignature};
+use super::db::stores::{ValidatorStore, ValidatorStoreError};
+use super::db::ClientDB;
+use super::types::{AttestationData, Bitfield, BitfieldError};
+use super::{Error, Invalid, Outcome};
+
+/// Validate that some signature is correct for some attestation data and known validator set.
+pub fn validate_attestation_signature<T>(
+    attestation_data: &AttestationData,
+    participation_bitfield: &Bitfield,
+    aggregate_signature: &AggregateSignature,
+    attestation_indices: &[usize],
+    validator_store: &ValidatorStore<T>,
+) -> Result<Outcome, Error>
+where
+    T: ClientDB + Sized,
+{
+    let mut agg_pub_key = AggregatePublicKey::new();
+
+    for i in 0..attestation_indices.len() {
+        let voted = participation_bitfield.get(i)?;
+        if voted {
+            // De-reference the attestation index into a canonical ValidatorRecord index.
+            let validator = *attestation_indices.get(i).ok_or(Error::BadValidatorIndex)?;
+            // Load the public key.
+            let pub_key = validator_store
+                .get_public_key_by_index(validator)?
+                .ok_or(Error::NoPublicKeyForValidator)?;
+            // Aggregate the public key.
+            agg_pub_key.add(&pub_key);
+        }
+    }
+
+    let signed_message = attestation_data_signing_message(attestation_data);
+    verify_or!(
+        // TODO: ensure "domain" for aggregate signatures is included.
+        // https://github.com/sigp/lighthouse/issues/91
+        aggregate_signature.verify(&signed_message, &agg_pub_key),
+        reject!(Invalid::SignatureInvalid)
+    );
+
+    accept!()
+}
+
+fn attestation_data_signing_message(attestation_data: &AttestationData) -> Vec<u8> {
+    let mut signed_message = attestation_data.canonical_root().to_vec();
+    signed_message.append(&mut vec![0]);
+    signed_message
+}
+
+impl From<ValidatorStoreError> for Error {
+    fn from(error: ValidatorStoreError) -> Self {
+        match error {
+            ValidatorStoreError::DBError(s) => Error::DBError(s),
+            ValidatorStoreError::DecodeError => Error::PublicKeyCorrupt,
+        }
+    }
+}
+
+impl From<BitfieldError> for Error {
+    fn from(_error: BitfieldError) -> Self {
+        Error::OutOfBoundsBitfieldIndex
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::super::bls::{Keypair, Signature};
+    use super::super::db::MemoryDB;
+    use super::*;
+    use std::sync::Arc;
+
+    /*
+     * TODO: Test cases are not comprehensive.
+     * https://github.com/sigp/lighthouse/issues/94
+     */
+
+    #[test]
+    fn test_signature_verification() {
+        let attestation_data = AttestationData::zero();
+        let message = attestation_data_signing_message(&attestation_data);
+        let signing_keypairs = vec![
+            Keypair::random(),
+            Keypair::random(),
+            Keypair::random(),
+            Keypair::random(),
+            Keypair::random(),
+            Keypair::random(),
+        ];
+        let non_signing_keypairs = vec![
+            Keypair::random(),
+            Keypair::random(),
+            Keypair::random(),
+            Keypair::random(),
+            Keypair::random(),
+            Keypair::random(),
+        ];
+        /*
+         * Signing keypairs first, then non-signing
+         */
+        let mut all_keypairs = signing_keypairs.clone();
+        all_keypairs.append(&mut non_signing_keypairs.clone());
+
+        let attestation_indices: Vec<usize> = (0..all_keypairs.len()).collect();
+        let mut bitfield = Bitfield::from_elem(all_keypairs.len(), false);
+        for i in 0..signing_keypairs.len() {
+            bitfield.set(i, true).unwrap();
+        }
+
+        let db = Arc::new(MemoryDB::open());
+        let store = ValidatorStore::new(db);
+
+        for (i, keypair) in all_keypairs.iter().enumerate() {
+            store.put_public_key_by_index(i, &keypair.pk).unwrap();
+        }
+
+        let mut agg_sig = AggregateSignature::new();
+        for keypair in &signing_keypairs {
+            let sig = Signature::new(&message, &keypair.sk);
+            agg_sig.add(&sig);
+        }
+
+        /*
+         * Test using all valid parameters.
+         */
+        let outcome = validate_attestation_signature(
+            &attestation_data,
+            &bitfield,
+            &agg_sig,
+            &attestation_indices,
+            &store,
+        ).unwrap();
+        assert_eq!(outcome, Outcome::Valid);
+
+        /*
+         * Add another validator to the bitfield, run validation will all other
+         * parameters the same and assert that it fails.
+         */
+        bitfield.set(signing_keypairs.len() + 1, true).unwrap();
+        let outcome = validate_attestation_signature(
+            &attestation_data,
+            &bitfield,
+            &agg_sig,
+            &attestation_indices,
+            &store,
+        ).unwrap();
+        assert_eq!(outcome, Outcome::Invalid(Invalid::SignatureInvalid));
+    }
+}