+
−/* arcfour.c --- The arcfour stream cipher
+
− * Copyright (C) 2000-2003, 2005-2006, 2009-2015 Free Software Foundation, Inc.
+
− *
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− * This file is free software; you can redistribute it and/or modify
+
− * it under the terms of the GNU General Public License as published
+
− * by the Free Software Foundation; either version 2, or (at your
+
− * option) any later version.
+
− *
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− * This file is distributed in the hope that it will be useful, but
+
− * WITHOUT ANY WARRANTY; without even the implied warranty of
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− * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+
− * General Public License for more details.
+
− *
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− * You should have received a copy of the GNU General Public License
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− * along with this file; if not, see <http://www.gnu.org/licenses/>.
+
− *
+
− */
+
−
+
−/* Code from Libgcrypt adapted for gnulib by Simon Josefsson. */
+
−
+
−/*
+
− * For a description of the algorithm, see:
+
− *   Bruce Schneier: Applied Cryptography. John Wiley & Sons, 1996.
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− *   ISBN 0-471-11709-9. Pages 397 ff.
+
− */
+
−
+
−#include <config.h>
+
−
+
−#include "arcfour.h"
+
−
+
−void
+
−arcfour_stream (arcfour_context * context, const char *inbuf, char *outbuf,
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−                size_t length)
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−{
+
−  uint8_t i = context->idx_i;
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−  uint8_t j = context->idx_j;
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−  char *sbox = context->sbox;
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−
+
−  for (; length > 0; length--)
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−    {
+
−      char t;
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−
+
−      i++;
+
−      j += sbox[i];
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−      t = sbox[i];
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−      sbox[i] = sbox[j];
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−      sbox[j] = t;
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−      *outbuf++ = (*inbuf++
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−                   ^ sbox[(0U + sbox[i] + sbox[j]) % ARCFOUR_SBOX_SIZE]);
+
−    }
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−
+
−  context->idx_i = i;
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−  context->idx_j = j;
+
−}
+
−
+
−void
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−arcfour_setkey (arcfour_context * context, const char *key, size_t keylen)
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−{
+
−  size_t i, j, k;
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−  char *sbox = context->sbox;
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−
+
−  context->idx_i = context->idx_j = 0;
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−  for (i = 0; i < ARCFOUR_SBOX_SIZE; i++)
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−    sbox[i] = i;
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−  for (i = j = k = 0; i < ARCFOUR_SBOX_SIZE; i++)
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−    {
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−      char t;
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−      j = (j + sbox[i] + key[k]) % ARCFOUR_SBOX_SIZE;
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−      t = sbox[i];
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−      sbox[i] = sbox[j];
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−      sbox[j] = t;
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−      if (++k == keylen)
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−        k = 0;
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−    }
+
−}