Import Mbed OS hard-float snapshot

connectivity/libraries/ppp/source/polarssl/ppp_arc4.c

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+/*
+ *  An implementation of the ARCFOUR algorithm
+ *
+ *  Based on XySSL: Copyright (C) 2006-2008  Christophe Devine
+ *
+ *  Copyright (C) 2009  Paul Bakker <polarssl_maintainer at polarssl dot org>
+ *
+ *  All rights reserved.
+ *
+ *  Redistribution and use in source and binary forms, with or without
+ *  modification, are permitted provided that the following conditions
+ *  are met:
+ *  
+ *    * Redistributions of source code must retain the above copyright
+ *      notice, this list of conditions and the following disclaimer.
+ *    * 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.
+ *    * Neither the names of PolarSSL or XySSL 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 COPYRIGHT HOLDERS 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 COPYRIGHT
+ *  OWNER 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.
+ */
+/*
+ *  The ARCFOUR algorithm was publicly disclosed on 94/09.
+ *
+ *  http://groups.google.com/group/sci.crypt/msg/10a300c9d21afca0
+ */
+
+#include "ppp_opts.h"
+#if PPP_SUPPORT && PPP_INCLUDED_POLARSSL_ARC4
+
+#include "polarssl/arc4.h"
+/*
+ * ARC4 key schedule
+ */
+void arc4_setup( arc4_context *ctx, unsigned char *key, int keylen )
+{
+    int i, j, k, a;
+    unsigned char *m;
+
+    ctx->x = 0;
+    ctx->y = 0;
+    m = ctx->m;
+
+    for( i = 0; i < 256; i++ )
+        m[i] = (unsigned char) i;
+
+    j = k = 0;
+
+    for( i = 0; i < 256; i++, k++ )
+    {
+        if( k >= keylen ) k = 0;
+
+        a = m[i];
+        j = ( j + a + key[k] ) & 0xFF;
+        m[i] = m[j];
+        m[j] = (unsigned char) a;
+    }
+}
+
+/*
+ * ARC4 cipher function
+ */
+void arc4_crypt( arc4_context *ctx, unsigned char *buf, int buflen )
+{
+    int i, x, y, a, b;
+    unsigned char *m;
+
+    x = ctx->x;
+    y = ctx->y;
+    m = ctx->m;
+
+    for( i = 0; i < buflen; i++ )
+    {
+        x = ( x + 1 ) & 0xFF; a = m[x];
+        y = ( y + a ) & 0xFF; b = m[y];
+
+        m[x] = (unsigned char) b;
+        m[y] = (unsigned char) a;
+
+        buf[i] = (unsigned char)
+            ( buf[i] ^ m[(unsigned char)( a + b )] );
+    }
+
+    ctx->x = x;
+    ctx->y = y;
+}
+
+#endif /* PPP_SUPPORT && PPP_INCLUDED_POLARSSL_DES */