Add (incompleted) process_attestations fn

src/state/transition/attestations.rs

@@ -0,0 +1,77 @@
+use super::validator_record::ValidatorRecord;
+use super::utils::types::Bitfield;
+use super::utils::bls::{ AggregateSignature, PublicKey };
+
+#[allow(unused_variables)]
+pub fn process_attestations(
+    validators: &Vec<ValidatorRecord>,
+    attestation_indicies: &Vec<usize>,
+    attestation_bitfield: &Bitfield,
+    msg: &Vec<u8>,
+    aggregate_sig: &AggregateSignature)
+    -> Option<Vec<usize>>
+{
+    let mut key_msg_tuples: Vec<(&PublicKey, &[u8])> = vec![];
+    let mut attesters: Vec<usize> = vec![];
+
+    assert_eq!(attestation_indicies.len(), attestation_bitfield.len());
+    for (bitfield_bit, validators_index) in attestation_indicies.iter().enumerate() {
+        if attestation_bitfield.get_bit(&bitfield_bit) {
+            key_msg_tuples.push(
+                (&validators[*validators_index].pubkey,
+                &msg)
+                );
+            attesters.push(*validators_index);
+        }
+    }
+    // TODO: figure out why this assert exists in the Python impl.
+    assert!(attesters.len() <= 128, "Max attesters is 128.");
+    
+    /*
+    // TODO: ensure signature verification actually takes place.
+    // It is completely bypassed here.
+    match aggregate_sig.verify(&key_msg_tuples) {
+        false => None,
+        true => Some(attesters)
+    }
+    */
+    Some(attesters)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_attestation_processing() {
+        let validator_count = 10;
+        let mut validators: Vec<ValidatorRecord> = vec![];
+        let mut attestation_indicies: Vec<usize> = vec![];
+        let mut bitfield = Bitfield::new();
+        let mut agg_sig = AggregateSignature::new();
+        let msg = "Message that's longer than 16 chars".as_bytes();
+        
+        for i in 0..validator_count {
+            let (v, keypair) = 
+                ValidatorRecord::zero_with_thread_rand_keypair();
+            validators.push(v);
+            attestation_indicies.push(i);
+            bitfield.set_bit(&i, &true);
+            let sig = keypair.sign(&msg);
+            agg_sig.aggregate(&sig);
+        }
+
+        let result = process_attestations(
+            &validators,
+            &attestation_indicies,
+            &bitfield,
+            &msg.to_vec(),
+            &agg_sig);
+
+        match result {
+            None => panic!("Verification failed."),
+            Some(x) => println!("{:?}", x)
+        };
+    }
+}
+

src/state/transition/mod.rs

@@ -10,3 +10,4 @@ pub mod crosslinks;
 pub mod deposits;
 pub mod shuffling;
 pub mod validators;
+pub mod attestations;