Make Hash module public

Fixes #63

src/hash.rs

@@ -3,6 +3,8 @@
 // This source code is licensed under the MIT license found in the
 // LICENSE file in the root directory of this source tree.
 
+//! A convenience trait for digest bounds used throughout the library
+
 use digest::{BlockInput, FixedOutput, Reset, Update};
 
 /// Trait inheriting the requirements from digest::Digest for compatibility with HKDF and HMAC

src/lib.rs

@@ -411,7 +411,7 @@ pub mod opaque;
 
 pub mod ciphersuite;
 mod envelope;
-mod hash;
+pub mod hash;
 
 mod elligator;
 pub mod group;