add rust bindings for ed25519

Change-Id: I7458b1d7aa1736d586dc80660d59c07fa2ac1c8a
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/59805
Reviewed-by: Bob Beck <bbe@google.com>
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
diff --git a/rust/bssl-crypto/src/lib.rs b/rust/bssl-crypto/src/lib.rs
index 6ccf09c..2c80ae8 100644
--- a/rust/bssl-crypto/src/lib.rs
+++ b/rust/bssl-crypto/src/lib.rs
@@ -32,6 +32,9 @@
 /// BoringSSL implemented hash functions.
 pub mod digest;
 
+/// BoringSSL implemented Ed25519 operations.
+pub mod ed25519;
+
 /// BoringSSL implemented hkdf operations.
 pub mod hkdf;
 
@@ -62,6 +65,10 @@
             self.0.as_ptr() as *const T
         }
     }
+
+    pub fn len(&self) -> usize {
+        self.0.len()
+    }
 }
 
 /// This is a helper struct which provides functions for passing mutable slices over FFI.