add crypto_sign_ed25519_sk_to_pk

c_src/enacl_nif.c

@@ -203,6 +203,27 @@ ERL_NIF_TERM enif_crypto_sign_ed25519_keypair(ErlNifEnv *env, int argc, ERL_NIF_
 	return enif_make_tuple2(env, enif_make_binary(env, &pk), enif_make_binary(env, &sk));
 }
 
+static
+ERL_NIF_TERM enif_crypto_sign_ed25519_sk_to_pk(ErlNifEnv *env, int argc, ERL_NIF_TERM const argv[]) {
+	ErlNifBinary pk, sk;
+
+	if ((argc != 1) 
+			|| (!enif_inspect_binary(env, argv[0], &sk))
+			|| (sk.size != crypto_sign_ed25519_SECRETKEYBYTES)) {
+		return enif_make_badarg(env);
+	}
+
+	if (!enif_alloc_binary(crypto_sign_ed25519_PUBLICKEYBYTES, &pk)) {
+		return nacl_error_tuple(env, "alloc_failed");
+	}
+
+	if (crypto_sign_ed25519_sk_to_pk(pk.data, sk.data) != 0) {
+		return nacl_error_tuple(env, "crypto_sign_ed25519_sk_to_pk_failed");
+	}
+
+	return enif_make_binary(env, &pk);
+}
+
 static
 ERL_NIF_TERM enif_crypto_sign_ed25519_public_to_curve25519(ErlNifEnv *env, int argc, ERL_NIF_TERM const argv[]) {
 	ErlNifBinary curve25519_pk, ed25519_pk;
@@ -1735,6 +1756,7 @@ static ErlNifFunc nif_funcs[] = {
 	erl_nif_dirty_job_cpu_bound_macro("crypto_curve25519_scalarmult_base", 1, enif_crypto_curve25519_scalarmult_base),
 
 	erl_nif_dirty_job_cpu_bound_macro("crypto_sign_ed25519_keypair", 0, enif_crypto_sign_ed25519_keypair),
+	{"crypto_sign_ed25519_sk_to_pk", 1, enif_crypto_sign_ed25519_sk_to_pk},
 	{"crypto_sign_ed25519_public_to_curve25519", 1, enif_crypto_sign_ed25519_public_to_curve25519},
 	{"crypto_sign_ed25519_secret_to_curve25519", 1, enif_crypto_sign_ed25519_secret_to_curve25519},
 	{"crypto_sign_ed25519_PUBLICKEYBYTES", 0, enif_crypto_sign_ed25519_PUBLICKEYBYTES},

src/enacl.erl

@@ -137,6 +137,7 @@
 -export([
          %% No Tests!
          crypto_sign_ed25519_keypair/0,
+         crypto_sign_ed25519_sk_to_pk/1,
          crypto_sign_ed25519_public_to_curve25519/1,
          crypto_sign_ed25519_secret_to_curve25519/1,
          crypto_sign_ed25519_public_size/0,
@@ -957,6 +958,12 @@ crypto_sign_ed25519_keypair() ->
     {PK, SK} = enacl_nif:crypto_sign_ed25519_keypair(),
     #{ public => PK, secret => SK }.
 
+%% @doc TODO
+%% @end
+-spec crypto_sign_ed25519_sk_to_pk(Secret :: binary()) -> binary().
+crypto_sign_ed25519_sk_to_pk(Secret) ->
+    enacl_nif:crypto_sign_ed25519_sk_to_pk(Secret).
+
 %% @doc crypto_sign_ed25519_public_to_curve25519/1 converts a given Ed 25519 public
 %% key to a Curve 25519 public key.
 %% @end

src/enacl_nif.erl

@@ -105,6 +105,7 @@
 %% Ed 25519
 -export([
          crypto_sign_ed25519_keypair/0,
+         crypto_sign_ed25519_sk_to_pk/1,
          crypto_sign_ed25519_public_to_curve25519/1,
          crypto_sign_ed25519_secret_to_curve25519/1,
          crypto_sign_ed25519_PUBLICKEYBYTES/0,
@@ -277,6 +278,7 @@ crypto_curve25519_scalarmult(_Secret, _BasePoint) -> erlang:nif_error(nif_not_lo
 crypto_curve25519_scalarmult_base(_Secret) -> erlang:nif_error(nif_not_loaded).
 
 crypto_sign_ed25519_keypair() -> erlang:nif_error(nif_not_loaded).
+crypto_sign_ed25519_sk_to_pk(_SecretKey) -> erlang:nif_error(nif_not_loaded).
 crypto_sign_ed25519_public_to_curve25519(_PublicKey) -> erlang:nif_error(nif_not_loaded).
 crypto_sign_ed25519_secret_to_curve25519(_SecretKey) -> erlang:nif_error(nif_not_loaded).
 crypto_sign_ed25519_PUBLICKEYBYTES() -> erlang:nif_error(nif_not_loaded).