From 872c0e803a95b9211f55cd4c8d6af09424343fcb Mon Sep 17 00:00:00 2001
From: Marcel Holtmann <marcel@holtmann.org>
Date: Sat, 27 Dec 2014 06:58:28 +0100
Subject: [PATCH] core: Add support for HMAC SHA256 helper function

---
 Makefile.am  |  1 +
 src/sha256.c | 93 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/sha256.h | 26 +++++++++++++++
 3 files changed, 120 insertions(+)
 create mode 100644 src/sha256.c
 create mode 100644 src/sha256.h

diff --git a/Makefile.am b/Makefile.am
index 8cb3b37c..e7e13c51 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -45,6 +45,7 @@ src_iwd_SOURCES = src/main.c linux/nl80211.h linux/kdbus.h \
 					src/wiphy.h src/wiphy.c \
 					src/md5.h src/md5.c \
 					src/sha1.h src/sha1.c \
+					src/sha256.h src/sha256.c \
 					src/ie.h src/ie.c \
 					src/dbus.h src/dbus.c \
 					src/manager.h src/manager.c \
diff --git a/src/sha256.c b/src/sha256.c
new file mode 100644
index 00000000..de1dffaf
--- /dev/null
+++ b/src/sha256.c
@@ -0,0 +1,93 @@
+/*
+ *
+ *  Wireless daemon for Linux
+ *
+ *  Copyright (C) 2013-2014  Intel Corporation. All rights reserved.
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Lesser General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2.1 of the License, or (at your option) any later version.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <string.h>
+#include <ell/ell.h>
+
+#include "src/sha256.h"
+
+#define SHA256_MAC_LEN 32
+
+static void __hmac_sha256(struct l_checksum *checksum,
+			const void *key, size_t key_len,
+			const void *data, size_t data_len, void *output)
+{
+	unsigned char ipad[64];
+	unsigned char opad[64];
+	unsigned char digest[SHA256_MAC_LEN];
+	int i;
+
+	/* if key is longer than 64 bytes reset it to key=SHA256(key) */
+	if (key_len > 64) {
+		l_checksum_update(checksum, key, key_len);
+		l_checksum_get_digest(checksum, digest, SHA256_MAC_LEN);
+
+		l_checksum_reset(checksum);
+
+		key = digest;
+		key_len = SHA256_MAC_LEN;
+	}
+
+	/* start out by storing key in pads */
+	memset(ipad, 0, sizeof(ipad));
+	memset(opad, 0, sizeof(opad));
+	memcpy(ipad, key, key_len);
+	memcpy(opad, key, key_len);
+
+	/* XOR key with ipad and opad values */
+	for (i = 0; i < 64; i++) {
+		ipad[i] ^= 0x36;
+		opad[i] ^= 0x5c;
+	}
+
+	/* perform inner SHA256 */
+	l_checksum_update(checksum, ipad, sizeof(ipad));
+	l_checksum_update(checksum, data, data_len);
+	l_checksum_get_digest(checksum, digest, SHA256_MAC_LEN);
+
+	l_checksum_reset(checksum);
+
+	/* perform outer SHA256 */
+	l_checksum_update(checksum, opad, sizeof(opad));
+	l_checksum_update(checksum, digest, SHA256_MAC_LEN);
+	l_checksum_get_digest(checksum, output, SHA256_MAC_LEN);
+
+	l_checksum_reset(checksum);
+}
+
+bool hmac_sha256(const void *key, size_t key_len,
+                const void *data, size_t data_len, void *output, size_t size)
+{
+	struct l_checksum *checksum;
+
+	checksum = l_checksum_new(L_CHECKSUM_SHA256);
+
+	__hmac_sha256(checksum, key, key_len, data, data_len, output);
+
+	l_checksum_free(checksum);
+
+	return true;
+}
diff --git a/src/sha256.h b/src/sha256.h
new file mode 100644
index 00000000..3faa33d5
--- /dev/null
+++ b/src/sha256.h
@@ -0,0 +1,26 @@
+/*
+ *
+ *  Wireless daemon for Linux
+ *
+ *  Copyright (C) 2013-2014  Intel Corporation. All rights reserved.
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Lesser General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2.1 of the License, or (at your option) any later version.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ */
+
+#include <stdbool.h>
+
+bool hmac_sha256(const void *key, size_t key_len,
+		const void *data, size_t data_len, void *output, size_t size);