Added/modified types and constants according to specs

beacon_chain/utils/bls/src/signature.rs

@@ -35,6 +35,12 @@ impl Signature {
     pub fn as_raw(&self) -> &RawSignature {
         &self.0
     }
+
+    /// Returns a new empty signature.
+    pub fn empty_sig() -> Self {
+        let empty: Vec<u8> = vec![0; 97];
+        Signature(RawSignature::from_bytes(&empty).unwrap())
+    }
 }
 
 impl Encodable for Signature {
@@ -68,4 +74,16 @@ mod tests {
 
         assert_eq!(original, decoded);
     }
+
+    #[test]
+    pub fn test_empty_sig() {
+        let sig = Signature::empty_sig();
+
+        let sig_as_bytes: Vec<u8> = sig.as_raw().as_bytes();
+
+        assert_eq!(sig_as_bytes.len(), 97);
+        for one_byte in sig_as_bytes.iter() {
+            assert_eq!(*one_byte, 0);
+        }
+    }
 }