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/*
* Copyright 2001 Niels Provos <provos@citi.umich.edu>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Niels Provos.
* 4. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
*/
#include <sys/types.h>
#include "config.h"
#include <md5.h>
#include "arc4.h"
/*
* An arc4 stream generator is used for encryption and pseudo-random
* numbers.
*/
void
arc4_init(struct arc4_stream *as)
{
int n;
for (n = 0; n < 256; n++)
as->s[n] = n;
as->i = 0;
as->j = 0;
}
u_int8_t
arc4_getbyte(struct arc4_stream *as)
{
u_int8_t si, sj;
as->i = (as->i + 1);
si = as->s[as->i];
as->j = (as->j + si);
sj = as->s[as->j];
as->s[as->i] = sj;
as->s[as->j] = si;
return (as->s[(si + sj) & 0xff]);
}
void
arc4_skipbytes(struct arc4_stream *as, int skip)
{
u_int8_t i, j, si, sj;
u_int8_t *s;
s = as->s;
i = as->i;
j = as->j;
while (skip-- > 0) {
i = (i + 1) & 0xff;
si = s[i];
j = (si + j) & 0xff;
s[i] = sj = s[j];
s[j] = si;
}
as->i = i;
as->j = j;
}
u_int32_t
arc4_getword(struct arc4_stream *as)
{
u_int32_t val;
val = arc4_getbyte(as) << 24;
val |= arc4_getbyte(as) << 16;
val |= arc4_getbyte(as) << 8;
val |= arc4_getbyte(as);
return (val);
}
void
arc4_addrandom(struct arc4_stream *as, u_char *dat, int datlen)
{
int n;
u_int8_t si, ki, i, j, *s;
s = as->s;
i = as->i - 1;
j = as->j;
ki = 0;
for (n = 0; n < 256; n++) {
i++;
si = s[i];
j = (j + si + dat[ki]);
s[i] = s[j];
s[j] = si;
if (++ki >= datlen)
ki = 0;
}
as->i = i;
as->j = j;
}
void
arc4_initkey(struct arc4_stream *as, u_char *key, int keylen)
{
MD5_CTX ctx;
u_char digest[16];
/* Bah, we want bcrypt */
MD5Init(&ctx);
MD5Update(&ctx, key, keylen);
MD5Final(digest, &ctx);
arc4_init(as);
arc4_addrandom(as, digest, 16);
}
void
arc4_fixedkey(struct arc4_stream *as, u_char *key, int keylen)
{
u_char digest[5];
int i;
memset(digest, 0, sizeof(digest));
for (i = 0; i < keylen; i++)
digest[i % 5] ^= key[i];
arc4_init(as);
arc4_addrandom(as, digest, 5);
/* Reset */
as->i = as->j = 0;
}
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