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-rw-r--r--lib/crypto-algorithms/arcfour.c45
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diff --git a/lib/crypto-algorithms/arcfour.c b/lib/crypto-algorithms/arcfour.c
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+/*********************************************************************
+* Filename: arcfour.c
+* Author: Brad Conte (brad AT bradconte.com)
+* Copyright:
+* Disclaimer: This code is presented "as is" without any guarantees.
+* Details: Implementation of the ARCFOUR encryption algorithm.
+ Algorithm specification can be found here:
+ * http://en.wikipedia.org/wiki/RC4
+*********************************************************************/
+
+/*************************** HEADER FILES ***************************/
+#include <stdlib.h>
+#include "arcfour.h"
+
+/*********************** FUNCTION DEFINITIONS ***********************/
+void arcfour_key_setup(BYTE state[], const BYTE key[], int len)
+{
+ int i, j;
+ BYTE t;
+
+ for (i = 0; i < 256; ++i)
+ state[i] = i;
+ for (i = 0, j = 0; i < 256; ++i) {
+ j = (j + state[i] + key[i % len]) % 256;
+ t = state[i];
+ state[i] = state[j];
+ state[j] = t;
+ }
+}
+
+void arcfour_generate_stream(BYTE state[], BYTE out[], size_t len)
+{
+ int i, j;
+ size_t idx;
+ BYTE t;
+
+ for (idx = 0, i = 0, j = 0; idx < len; ++idx) {
+ i = (i + 1) % 256;
+ j = (j + state[i]) % 256;
+ t = state[i];
+ state[i] = state[j];
+ state[j] = t;
+ out[idx] = state[(state[i] + state[j]) % 256];
+ }
+}