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/*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
struct rc4_state
{
int x, y, m[256];
};
void rc4_setup( struct rc4_state *s, unsigned char *key, int length )
{
int i, j, k, *m, a;
s->x = 0;
s->y = 0;
m = s->m;
for( i = 0; i < 256; i++ )
{
m[i] = i;
}
j = k = 0;
for( i = 0; i < 256; i++ )
{
a = m[i];
j = (unsigned char) ( j + a + key[k] );
m[i] = m[j]; m[j] = a;
if( ++k >= length ) k = 0;
}
}
void rc4_crypt( struct rc4_state *s, unsigned char *data, int length )
{
int i, x, y, *m, a, b;
x = s->x;
y = s->y;
m = s->m;
for( i = 0; i < length; i++ )
{
x = (unsigned char) ( x + 1 ); a = m[x];
y = (unsigned char) ( y + a );
m[x] = b = m[y];
m[y] = a;
data[i] ^= m[(unsigned char) ( a + b )];
}
s->x = x;
s->y = y;
}
void rc4_crypt_sw(unsigned char *data, int ulMsgLength, unsigned char *rc4_key, unsigned long ulKeyLength )
{
struct rc4_state s;
rc4_setup( &s, rc4_key, ulKeyLength );
rc4_crypt( &s, data, ulMsgLength );
}
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