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/*
* pppcrypt.c - PPP/DES linkage for MS-CHAP and EAP SRP-SHA1
*
* Extracted from chap_ms.c by James Carlson.
*
* Copyright (c) 1995 Eric Rosenquist. 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. The name(s) of the authors of this software must not be used to
* endorse or promote products derived from this software without
* prior written permission.
*
* THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
* THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
* SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
* AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
* OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <errno.h>
#include "pppd.h"
#include "pppcrypt.h"
static u_char
Get7Bits(u_char *input, int startBit)
{
unsigned int word;
word = (unsigned)input[startBit / 8] << 8;
word |= (unsigned)input[startBit / 8 + 1];
word >>= 15 - (startBit % 8 + 7);
return word & 0xFE;
}
static void
MakeKey(u_char *key, u_char *des_key)
{
/* key IN 56 bit DES key missing parity bits */
/* des_key OUT 64 bit DES key with parity bits added */
des_key[0] = Get7Bits(key, 0);
des_key[1] = Get7Bits(key, 7);
des_key[2] = Get7Bits(key, 14);
des_key[3] = Get7Bits(key, 21);
des_key[4] = Get7Bits(key, 28);
des_key[5] = Get7Bits(key, 35);
des_key[6] = Get7Bits(key, 42);
des_key[7] = Get7Bits(key, 49);
#ifndef USE_CRYPT
DES_set_odd_parity((DES_cblock *)des_key);
#endif
}
#ifdef USE_CRYPT
/*
* in == 8-byte string (expanded version of the 56-bit key)
* out == 64-byte string where each byte is either 1 or 0
* Note that the low-order "bit" is always ignored by by setkey()
*/
static void
Expand(u_char *in, u_char *out)
{
int j, c;
int i;
for (i = 0; i < 64; in++){
c = *in;
for (j = 7; j >= 0; j--)
*out++ = (c >> j) & 01;
i += 8;
}
}
/* The inverse of Expand
*/
static void
Collapse(u_char *in, u_char *out)
{
int j;
int i;
unsigned int c;
for (i = 0; i < 64; i += 8, out++) {
c = 0;
for (j = 7; j >= 0; j--, in++)
c |= *in << j;
*out = c & 0xff;
}
}
bool
DesSetkey(u_char *key)
{
u_char des_key[8];
u_char crypt_key[66];
MakeKey(key, des_key);
Expand(des_key, crypt_key);
errno = 0;
setkey((const char *)crypt_key);
if (errno != 0)
return (0);
return (1);
}
bool
DesEncrypt(u_char *clear, u_char *cipher)
{
u_char des_input[66];
Expand(clear, des_input);
errno = 0;
encrypt((char *)des_input, 0);
if (errno != 0)
return (0);
Collapse(des_input, cipher);
return (1);
}
bool
DesDecrypt(u_char *cipher, u_char *clear)
{
u_char des_input[66];
Expand(cipher, des_input);
errno = 0;
encrypt((char *)des_input, 1);
if (errno != 0)
return (0);
Collapse(des_input, clear);
return (1);
}
#else /* USE_CRYPT */
static DES_key_schedule key_schedule;
bool
DesSetkey(u_char *key)
{
DES_cblock des_key;
MakeKey(key, des_key);
DES_set_key(&des_key, &key_schedule);
return (1);
}
bool
DesEncrypt(u_char *clear, u_char *cipher)
{
DES_ecb_encrypt((DES_cblock *)clear, (DES_cblock *)cipher,
&key_schedule, 1);
return (1);
}
bool
DesDecrypt(u_char *cipher, u_char *clear)
{
DES_ecb_encrypt((DES_cblock *)cipher, (DES_cblock *)clear,
&key_schedule, 0);
return (1);
}
#endif /* USE_CRYPT */
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