arc4: Add arc4_skip

Makefile.am

@@ -46,6 +46,7 @@ src_iwd_SOURCES = src/main.c linux/nl80211.h linux/kdbus.h \
 					src/netdev.h src/netdev.c \
 					src/wiphy.h src/wiphy.c \
 					src/aes.h src/aes.c \
+					src/arc4.h src/arc4.c \
 					src/md5.h src/md5.c \
 					src/sha1.h src/sha1.c \
 					src/sha256.h src/sha256.c \

src/arc4.c

@@ -0,0 +1,54 @@
+/*
+ *
+ *  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
+
+#define _GNU_SOURCE
+#include <ell/ell.h>
+
+#include "src/arc4.h"
+
+bool arc4_skip(const uint8_t *key, size_t key_len, size_t skip,
+		const uint8_t *in, size_t len, uint8_t *out)
+{
+	char skip_buf[1024];
+	struct l_cipher *cipher;
+
+	cipher = l_cipher_new(L_CIPHER_ARC4, key, key_len);
+	if (!cipher)
+		return false;
+
+	while (skip > 0) {
+		size_t to_skip =
+			skip > sizeof(skip_buf) ? sizeof(skip_buf) : skip;
+
+		l_cipher_decrypt(cipher, skip_buf, skip_buf, to_skip);
+		skip -= to_skip;
+	}
+
+	l_cipher_decrypt(cipher, in, out, len);
+	l_cipher_free(cipher);
+
+	return true;
+}

src/arc4.h

@@ -0,0 +1,27 @@
+/*
+ *
+ *  Wireless daemon for Linux
+ *
+ *  Copyright (C) 2013-2015  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>
+#include <stdint.h>
+
+bool arc4_skip(const uint8_t *key, size_t key_len, size_t skip,
+		const uint8_t *in, size_t len, uint8_t *out);