From 2ab3d99967d68c79351fe2a3df22c445447e3010 Mon Sep 17 00:00:00 2001
From: Michał Cichoń <michcic@gmail.com>
Date: Tue, 15 Nov 2011 22:28:48 +0100
Subject: Initial import.

---
 axTLS/src/crypto/rc4.c | 92 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 92 insertions(+)
 create mode 100644 axTLS/src/crypto/rc4.c

(limited to 'axTLS/src/crypto/rc4.c')

diff --git a/axTLS/src/crypto/rc4.c b/axTLS/src/crypto/rc4.c
new file mode 100644
index 0000000..12a1211
--- /dev/null
+++ b/axTLS/src/crypto/rc4.c
@@ -0,0 +1,92 @@
+/*
+ * Copyright (c) 2007, Cameron Rich
+ * 
+ * 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 name of the axTLS project 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.
+ */
+
+/**
+ * An implementation of the RC4/ARC4 algorithm.
+ * Originally written by Christophe Devine.
+ */
+
+#include <string.h>
+#include "os_port.h"
+#include "crypto.h"
+
+/**
+ * Get ready for an encrypt/decrypt operation
+ */
+void RC4_setup(RC4_CTX *ctx, const uint8_t *key, int length)
+{
+    int i, j = 0, k = 0, a;
+    uint8_t *m;
+
+    ctx->x = 0;
+    ctx->y = 0;
+    m = ctx->m;
+
+    for (i = 0; i < 256; i++)
+        m[i] = i;
+
+    for (i = 0; i < 256; i++)
+    {
+        a = m[i];
+        j = (uint8_t)(j + a + key[k]);
+        m[i] = m[j]; 
+        m[j] = a;
+
+        if (++k >= length) 
+            k = 0;
+    }
+}
+
+/**
+ * Perform the encrypt/decrypt operation (can use it for either since
+ * this is a stream cipher).
+ * NOTE: *msg and *out must be the same pointer (performance tweak)
+ */
+void RC4_crypt(RC4_CTX *ctx, const uint8_t *msg, uint8_t *out, int length)
+{ 
+    int i;
+    uint8_t *m, x, y, a, b;
+
+    x = ctx->x;
+    y = ctx->y;
+    m = ctx->m;
+
+    for (i = 0; i < length; i++)
+    {
+        a = m[++x];
+        y += a;
+        m[x] = b = m[y];
+        m[y] = a;
+        out[i] ^= m[(uint8_t)(a + b)];
+    }
+
+    ctx->x = x;
+    ctx->y = y;
+}
-- 
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