Improvements re: suggestions from @jlouis.

c_src/enacl_nif.c

@@ -522,7 +522,7 @@ ERL_NIF_TERM enif_crypto_sign_detached(ErlNifEnv* env, int argc, ERL_NIF_TERM co
 
         crypto_sign_detached(sig.data, &siglen, m.data, m.size, sk.data);
 
-        return enif_make_sub_binary(env, enif_make_binary(env, &sig), 0, siglen);
+        return enif_make_binary(env, &sig);
 }
 
 /*
@@ -955,8 +955,8 @@ static ErlNifFunc nif_funcs[] = {
 	{"crypto_sign_open_b", 2, enif_crypto_sign_open},
 	{"crypto_sign_open", 2, enif_crypto_sign_open, ERL_NIF_DIRTY_JOB_CPU_BOUND},
 
-        {"crypto_sign_detached", 2, enif_crypto_sign_detached, ERL_NIF_DIRTY_JOB_CPU_BOUND},
-        {"crypto_sign_verify_detached", 3, enif_crypto_sign_verify_detached, ERL_NIF_DIRTY_JOB_CPU_BOUND},
+    {"crypto_sign_detached", 2, enif_crypto_sign_detached, ERL_NIF_DIRTY_JOB_CPU_BOUND},
+    {"crypto_sign_verify_detached", 3, enif_crypto_sign_verify_detached, ERL_NIF_DIRTY_JOB_CPU_BOUND},
 
 	{"crypto_secretbox_NONCEBYTES", 0, enif_crypto_secretbox_NONCEBYTES},
 	{"crypto_secretbox_ZEROBYTES", 0, enif_crypto_secretbox_ZEROBYTES},

src/enacl.erl

@@ -398,12 +398,16 @@ sign_detached(M, SK) -> enacl_nif:crypto_sign_detached(M, SK).
 %%
 %% Given a signature `SIG', a message `M', and a public key `PK', the function computes
 %% true iff the `SIG' is valid for `M' and `PK'.
--spec sign_verify_detached(SIG, M, PK) -> boolean()
+-spec sign_verify_detached(SIG, M, PK) -> {ok, M} | {error, failed_verification}
   when
     SIG :: binary(),
     M   :: iodata(),
     PK  :: binary().
-sign_verify_detached(SIG, M, PK) -> enacl_nif:crypto_sign_verify_detached(SIG, M, PK).
+sign_verify_detached(SIG, M, PK) ->
+    case enacl_nif:crypto_sign_verify_detached(SIG, M, PK) of
+        true  -> {ok, M};
+        false -> {error, failed_verification}
+    end.
 
 %% @private
 -spec box_secret_key_bytes() -> pos_integer().