* Copyright (c) 1985 Corporation for Research and Educational Networking

/*
* Copyright (c) 1985 Corporation for Research and Educational Networking
* Copyright (c) 1988 University of Illinois Board of Trustees, Steven
* Dorner, and Paul Pomes
* 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 the Corporation for
* Research and Educational Networking (CREN), the University of
* Illinois at Urbana, and their contributors.
* 4. Neither the name of CREN, the University nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE TRUSTEES AND CONTRIBUTORS ``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 TRUSTEES OR CONTRIBUTORS 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.
*/

#ifndef lint
static char RcsId[] = "@(#)$Id: cryptit.c,v 1.3 1994/03/11 23:14:20 paul Exp $";
#endif

#ifdef PH
# ifdef __STDC__
# include <string.h>
# else /* !__STDC__ */
# include <strings.h>
# endif /* __STDC__ */
# include <ctype.h>
# include "qiapi.h"
#else /* !PH */
# include "protos.h"
#endif /* PH */

#define ROTORSZ 256
#define MASK 0377

#include <sys/types.h>
#include <sys/stat.h>
#include <signal.h>
#include <sgtty.h>

static char t1[ROTORSZ];
static char t2[ROTORSZ];
static char t3[ROTORSZ];

static int Encrypting = 0;
static int ccnt, nchars, n1, n2;

static void crypt_init __P((char *));
static void threecpy __P((unsigned char *, unsigned char *));

void
crypt_start(pass)
char *pass;
{

n1 = 0;
n2 = 0;
ccnt = 0;
nchars = 0;
Encrypting = 1;
crypt_init(pass);
}

char *
decrypt(to, from)
char *to, *from;
{
char scratch[4096];
char *sp;
int count;

count = decode((unsigned char *) scratch, (unsigned char *) from);
for (sp = scratch; count--; sp++)
{
*to++ = t2[(t3[(t1[(*sp + n1) & MASK] + n2) & MASK] - n2) & MASK] - n1;

n1++;
if (n1 == ROTORSZ)
{
n1 = 0;
n2++;
if (n2 == ROTORSZ)
n2 = 0;
}
}
*to = '\0'; /* null-terminate */
return (0);
}

void
decrypt_end()
{
Encrypting = 0;
}

/* single character decode */
#define DEC(c) (((unsigned char)(c) - '#') & 077)

int
decode(to, from)
unsigned char *to, *from;
{
int n;
int chars;

chars = n = DEC(*from++);

while (n > 0)
{
/*
* convert groups of 3 bytes (4 Input characters).
*/
*to++ = DEC(*from) << 2 | DEC(from[1]) >> 4;
*to++ = DEC(from[1]) << 4 | DEC(from[2]) >> 2;
*to++ = DEC(from[2]) << 6 | DEC(from[3]);
from += 4;
n -= 3;
}
return (chars);
}

static void
crypt_init(pw)
char *pw;
{
int ic, i, k, temp;
unsigned random;
char buf[13];
int seed;
char *crypt();

/* must reinitialize the arrays */
for (i = 0; i < ROTORSZ; i++)
t1[i] = t2[i] = t3[i] = 0;

#ifdef PRE_ENCRYPT
strncpy(buf, pw, 13);
#else
strncpy(buf, crypt(pw, pw), 13);
#endif

seed = 123;
for (i = 0; i < 13; i++)
seed = seed * buf[i] + i;
for (i = 0; i < ROTORSZ; i++)
t1[i] = i;
for (i = 0; i < ROTORSZ; i++)
{
seed = 5 * seed + buf[i % 13];
random = seed % 65521;
k = ROTORSZ - 1 - i;
ic = (random & MASK) % (k + 1);
random >>= 8;
temp = t1[k];
t1[k] = t1[ic];
t1[ic] = temp;
if (t3[k] != 0)
continue;
ic = (random & MASK) % k;
while (t3[ic] != 0)
ic = (ic + 1) % k;
t3[k] = ic;
t3[ic] = k;
}
for (i = 0; i < ROTORSZ; i++)
t2[t1[i] & MASK] = i;
}

/*
* encrypts a string
* first byte of string is encoded length of string
* returns length of encoded string
*/
int
encryptit(to, from)
char *to, *from;
{
char scratch[4096];
char *sp;

sp = scratch;
for (; *from; from++)
{
*sp++ = t2[(t3[(t1[(*from + n1) & MASK] + n2) & MASK] - n2) & MASK] - n1;
n1++;
if (n1 == ROTORSZ)
{
n1 = 0;
n2++;
if (n2 == ROTORSZ)
n2 = 0;
}
}
return (encode(to, scratch, sp - scratch));
}

/*
* Basic 1 character encoding function to make a char printing.
*/
#define ENC(c) (((unsigned char)(c) & 077) + '#')

int
encode(out, buf, n)
char *out, *buf;
int n;
{
int i;
char *outStart;

outStart = out;
*out++ = ENC(n);

for (i = 0; i < n; buf += 3, i += 3, out += 4)
threecpy((unsigned char *) out, (unsigned char *) buf);

/* null terminate */
*out = '\0';
return (out - outStart);
}

static void
threecpy(to, from)
unsigned char *to, *from;
{
int c1, c2, c3, c4;

c1 = *from >> 2;
c2 = (*from << 4) & 060 | (from[1] >> 4) & 017;
c3 = (from[1] << 2) & 074 | (from[2] >> 6) & 03;
c4 = from[2] & 077;
*to++ = ENC(c1);
*to++ = ENC(c2);
*to++ = ENC(c3);
*to = ENC(c4);
}