src/types.ml

@@ -84,13 +84,18 @@ end = struct
     (* mirage_crypto: "The result is the concatenation of r and s, as specified in RFC 8032." *)
     Mirage_crypto_ec.Ed25519.sign ~key s
 
-  let of_b32 s = B32.decode s
+  let check_size t =
+    match String.length t = 64 with
+    | false -> Error "EddsaSignature: invalid string length"
+    | true -> Ok ()
 
-  let to_b32 t =
-    let s = B32.encode t in
-    assert (String.length s = 64);
-    s
+  let of_b32 s =
+    let open Syntax in
+    let* t = B32.decode s in
+    let+ () = check_size t in
+    t
 
+  let to_b32 = B32.encode
   let jsont = Jsont.of_of_string ~kind:"EddsaSignature" of_b32 ~enc:to_b32
 end