crypto: Add passphrase generation utility

Makefile.am

@@ -47,6 +47,7 @@ src_iwd_SOURCES = src/main.c linux/nl80211.h linux/kdbus.h \
 					src/ie.h src/ie.c \
 					src/dbus.h src/dbus.c \
 					src/manager.h src/manager.c \
+					src/crypto.h src/crypto.c \
 					iwd.h
 src_iwd_LDADD = ell/libell-internal.la
 

src/crypto.c

@@ -0,0 +1,87 @@
+/*
+ *
+ *  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 <stdbool.h>
+#include <string.h>
+#include <errno.h>
+
+#include <ell/ell.h>
+
+#include "sha1.h"
+#include "crypto.h"
+
+int crypto_psk_from_passphrase(const char *passphrase,
+				const unsigned char *ssid, size_t ssid_len,
+				unsigned char *out_psk)
+{
+	size_t passphrase_len;
+	size_t i;
+	bool result;
+	unsigned char psk[32];
+
+	if (!passphrase)
+		return -EINVAL;
+
+	if (!ssid)
+		return -EINVAL;
+
+	/*
+	 * IEEE 802.11, Annex M, Section M.4.1:
+	 * "A pass-phrase is a sequence of between 8 and 63 ASCII-encoded
+	 * characters. The limit of 63 comes from the desire to distinguish
+	 * between a pass-phrase and a PSK displayed as 64 hexadecimal
+	 * characters."
+	 */
+	passphrase_len = strlen(passphrase);
+	if (passphrase_len < 8 || passphrase_len > 63)
+		return -ERANGE;
+
+	if (ssid_len == 0 || ssid_len > 32)
+		return -ERANGE;
+
+	/* IEEE 802.11, Annex M, Section M.4.1:
+	 * "Each character in the pass-phrase must have an encoding in the
+	 * range of 32 to 126 (decimal), inclusive."
+	 *
+	 * This corresponds to printable characters only
+	 */
+	for (i = 0; i < passphrase_len; i++) {
+		if (l_ascii_isprint(passphrase[i]))
+			continue;
+
+		return -EINVAL;
+	}
+
+	result = pbkdf2_sha1(passphrase, passphrase_len, ssid, ssid_len,
+				4096, psk, sizeof(psk));
+	if (!result)
+		return -ENOKEY;
+
+	if (out_psk)
+		memcpy(out_psk, psk, sizeof(psk));
+
+	return 0;
+}

src/crypto.h

@@ -0,0 +1,27 @@
+/*
+ *
+ *  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 <stddef.h>
+
+int crypto_psk_from_passphrase(const char *passphrase,
+				const unsigned char *ssid, size_t ssid_len,
+				unsigned char *out_psk);