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+/*
+ * Copyright (c) 2004 Kungliga Tekniska Högskolan
+ * (Royal Institute of Technology, Stockholm, Sweden).
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * 3. Neither the name of the Institute nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+/* implemented from description in draft-kaukonen-cipher-arcfour-03.txt */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+
+RCSID("$Id: rc4.c,v 1.1 2004/03/25 16:40:59 lha Exp $");
+#endif
+
+#include <rc4.h>
+
+#define SWAP(k,x,y) \
+{ unsigned int _t; \
+ _t = k->state[x]; \
+ k->state[x] = k->state[y]; \
+ k->state[y] = _t; \
+}
+
+void
+RC4_set_key(RC4_KEY *key, const int len, unsigned char *data)
+{
+ int i, j;
+
+ for (i = 0; i < 256; i++)
+ key->state[i] = i;
+ for (i = 0, j = 0; i < 256; i++) {
+ j = (j + key->state[i] + data[i % len]) % 256;
+ SWAP(key, i, j);
+ }
+ key->x = key->y = 0;
+}
+
+void
+RC4(RC4_KEY *key, const int len, const unsigned char *in, unsigned char *out)
+{
+ int i, t;
+ unsigned x, y;
+
+ x = key->x;
+ y = key->y;
+ for (i = 0; i < len; i++) {
+ x = (x + 1) % 256;
+ y = (y + key->state[x]) % 256;
+ SWAP(key, x, y);
+ t = (key->state[x] + key->state[y]) % 256;
+ *out++ = key->state[t] ^ *in++;
+ }
+ key->x = x;
+ key->y = y;
+}