Add SignedRoot methods

eth2/utils/ssz/src/lib.rs

@@ -12,6 +12,7 @@ extern crate ethereum_types;
 
 pub mod decode;
 pub mod encode;
+mod signed_root;
 pub mod tree_hash;
 
 mod impl_decode;
@@ -20,6 +21,7 @@ mod impl_tree_hash;
 
 pub use crate::decode::{decode_ssz, decode_ssz_list, Decodable, DecodeError};
 pub use crate::encode::{Encodable, SszStream};
+pub use crate::signed_root::SignedRoot;
 pub use crate::tree_hash::{merkle_hash, TreeHash};
 
 pub use hashing::hash;

eth2/utils/ssz/src/signed_root.rs

@@ -0,0 +1,5 @@
+use crate::TreeHash;
+
+pub trait SignedRoot: TreeHash {
+    fn signed_root(&self) -> Vec<u8>;
+}