From 772a97d3dbf52eb4d582dc313c0930dfb4ebc4c8 Mon Sep 17 00:00:00 2001
From: Jesper Louis Andersen <jesper.louis.andersen@gmail.com>
Date: Mon, 24 Nov 2014 14:39:19 +0100
Subject: [PATCH] Implement low level code for the authenticators.

---
 c_src/enacl_nif.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 59 insertions(+)

diff --git a/c_src/enacl_nif.c b/c_src/enacl_nif.c
index b97d64f..a0dd801 100644
--- a/c_src/enacl_nif.c
+++ b/c_src/enacl_nif.c
@@ -177,6 +177,11 @@ ERL_NIF_TERM enif_crypto_stream_NONCEBYTES(ErlNifEnv *env, int argc, ERL_NIF_TER
 	return enif_make_int64(env, crypto_stream_NONCEBYTES);
 }
 
+static
+ERL_NIF_TERM enif_crypto_auth_KEYBYTES(ErlNifEnv *env, int argc, ERL_NIF_TERM const argv[]) {
+	return enif_make_int64(env, crypto_auth_KEYBYTES);
+}
+
 static
 ERL_NIF_TERM enif_crypto_secretbox(ErlNifEnv *env, int argc, ERL_NIF_TERM const argv[]) {
 	ErlNifBinary key, nonce, padded_msg, padded_ciphertext;
@@ -307,6 +312,56 @@ ERL_NIF_TERM enif_crypto_stream_xor(ErlNifEnv *env, int argc, ERL_NIF_TERM const
 	return enif_make_binary(env, &c);
 }
 
+static
+ERL_NIF_TERM enif_crypto_auth(ErlNifEnv *env, int argc, ERL_NIF_TERM const argv[]) {
+	ErlNifBinary a,m,k;
+
+	if (
+	  (argc != 2) ||
+	  (!enif_inspect_iolist_as_binary(env, argv[0], &m)) ||
+	  (!enif_inspect_iolist_as_binary(env, argv[1], &k))) {
+		return enif_make_badarg(env);
+	}
+	
+	if (k.size != crypto_auth_KEYBYTES) {
+		return enif_make_badarg(env);
+	}
+	
+	if (!enif_alloc_binary(crypto_auth_BYTES, &a)) {
+		return nacl_error_tuple(env, "alloc_failed");
+	}
+	
+	crypto_auth(a.data, m.data, m.size, k.data);
+	
+	return enif_make_binary(env, &a);
+}
+
+static
+ERL_NIF_TERM enif_crypto_auth_verify(ErlNifEnv *env, int argc, ERL_NIF_TERM const argv[]) {
+	ErlNifBinary a, m, k;
+	
+	if (
+	  (argc != 3) ||
+	  (!enif_inspect_iolist_as_binary(env, argv[0], &a)) ||
+	  (!enif_inspect_iolist_as_binary(env, argv[1], &m)) ||
+	  (!enif_inspect_iolist_as_binary(env, argv[2], &k))) {
+		return enif_make_badarg(env);
+	}
+	
+	if (
+	  (k.size != crypto_auth_KEYBYTES) ||
+	  (a.size != crypto_auth_BYTES)) {
+		return enif_make_badarg(env);
+	}
+	
+	if (0 == crypto_auth_verify(a.data, m.data, m.size, k.data)) {
+		return enif_make_atom(env, "true");
+	} else {
+		return enif_make_atom(env, "false");
+	}
+}
+	  
+
 /* Tie the knot to the Erlang world */
 static ErlNifFunc nif_funcs[] = {
 	{"crypto_box_NONCEBYTES", 0, enif_crypto_box_NONCEBYTES},
@@ -330,6 +385,10 @@ static ErlNifFunc nif_funcs[] = {
 	{"crypto_stream", 3, enif_crypto_stream, ERL_NIF_DIRTY_JOB_CPU_BOUND},
 	{"crypto_stream_xor", 3, enif_crypto_stream_xor, ERL_NIF_DIRTY_JOB_CPU_BOUND},
 
+	{"crypto_auth_KEYBYTES", 0, enif_crypto_auth_KEYBYTES},
+	{"crypto_auth", 2, enif_crypto_auth, ERL_NIF_DIRTY_JOB_CPU_BOUND},
+	{"crypto_auth_verify", 3, enif_crypto_auth_verify, ERL_NIF_DIRTY_JOB_CPU_BOUND},
+
 	{"crypto_hash", 1, enif_crypto_hash, ERL_NIF_DIRTY_JOB_CPU_BOUND}
 };