path: root/libcrypt/des.c

/*
 * FreeSec: libcrypt for NetBSD
 *
 * Copyright (c) 1994 David Burren
 * All rights reserved.
 *
 * Adapted for FreeBSD-2.0 by Geoffrey M. Rehmet
 *	this file should now *only* export crypt(), in order to make
 *	binaries of libcrypt exportable from the USA
 *
 * Adapted for FreeBSD-4.0 by Mark R V Murray
 *	this file should now *only* export crypt_des(), in order to make
 *	a module that can be optionally included in libcrypt.
 *
 * 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. Neither the name of the author nor the names of other contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 *
 * This is an original implementation of the DES and the crypt(3) interfaces
 * by David Burren <davidb@werj.com.au>.
 *
 * An excellent reference on the underlying algorithm (and related
 * algorithms) is:
 *
 *	B. Schneier, Applied Cryptography: protocols, algorithms,
 *	and source code in C, John Wiley & Sons, 1994.
 *
 * Note that in that book's description of DES the lookups for the initial,
 * pbox, and final permutations are inverted (this has been brought to the
 * attention of the author).  A list of errata for this book has been
 * posted to the sci.crypt newsgroup by the author and is available for FTP.
 *
 * ARCHITECTURE ASSUMPTIONS:
 *	It is assumed that the 8-byte arrays passed by reference can be
 *	addressed as arrays of u_int32_t's (ie. the CPU is not picky about
 *	alignment).
 */

#include <sys/cdefs.h>
#include <sys/types.h>
#include <sys/param.h>
#include <netinet/in.h>
#include <pwd.h>
#include <string.h>
#include <crypt.h>
#include "libcrypt.h"
#include "des_tables.c"

/* Re-entrantify me -- all this junk needs to be in
 * struct crypt_data to make this really reentrant... */
static u_int32_t en_keysl[16], en_keysr[16];
static u_int32_t de_keysl[16], de_keysr[16];
static u_int32_t saltbits;
static u_int32_t old_salt;
static u_int32_t old_rawkey0, old_rawkey1;

/* A pile of data */
static const u_char	ascii64[] = "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";

static const u_char	key_shifts[16] = {
	1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1
};

static const u_int32_t bits32[32] =
{
	0x80000000, 0x40000000, 0x20000000, 0x10000000,
	0x08000000, 0x04000000, 0x02000000, 0x01000000,
	0x00800000, 0x00400000, 0x00200000, 0x00100000,
	0x00080000, 0x00040000, 0x00020000, 0x00010000,
	0x00008000, 0x00004000, 0x00002000, 0x00001000,
	0x00000800, 0x00000400, 0x00000200, 0x00000100,
	0x00000080, 0x00000040, 0x00000020, 0x00000010,
	0x00000008, 0x00000004, 0x00000002, 0x00000001
};

static const u_char	bits8[8] = { 0x80, 0x40, 0x20, 0x10, 0x08, 0x04, 0x02, 0x01 };


static int
ascii_to_bin(char ch)
{
	if (ch > 'z')
		return(0);
	if (ch >= 'a')
		return(ch - 'a' + 38);
	if (ch > 'Z')
		return(0);
	if (ch >= 'A')
		return(ch - 'A' + 12);
	if (ch > '9')
		return(0);
	if (ch >= '.')
		return(ch - '.');
	return(0);
}

static void
des_init(void)
{
	static int des_initialised = 0;

	if (des_initialised==1)
		return;

	old_rawkey0 = old_rawkey1 = 0L;
	saltbits = 0L;
	old_salt = 0L;

	des_initialised = 1;
}

static void
setup_salt(u_int32_t salt)
{
	u_int32_t	obit, saltbit;
	int	i;

	if (salt == old_salt)
		return;
	old_salt = salt;

	saltbits = 0L;
	saltbit = 1;
	obit = 0x800000;
	for (i = 0; i < 24; i++) {
		if (salt & saltbit)
			saltbits |= obit;
		saltbit <<= 1;
		obit >>= 1;
	}
}


static void
des_setkey(const char *key)
{
	u_int32_t	k0, k1, rawkey0, rawkey1;
	int		shifts, round;

	des_init();

	rawkey0 = ntohl(*(const u_int32_t *) key);
	rawkey1 = ntohl(*(const u_int32_t *) (key + 4));

	if ((rawkey0 | rawkey1)
	    && rawkey0 == old_rawkey0
	    && rawkey1 == old_rawkey1) {
		/*
		 * Already setup for this key.
		 * This optimisation fails on a zero key (which is weak and
		 * has bad parity anyway) in order to simplify the starting
		 * conditions.
		 */
		return;
	}
	old_rawkey0 = rawkey0;
	old_rawkey1 = rawkey1;

	/*
	 *	Do key permutation and split into two 28-bit subkeys.
	 */
	k0 = key_perm_maskl[0][rawkey0 >> 25]
	   | key_perm_maskl[1][(rawkey0 >> 17) & 0x7f]
	   | key_perm_maskl[2][(rawkey0 >> 9) & 0x7f]
	   | key_perm_maskl[3][(rawkey0 >> 1) & 0x7f]
	   | key_perm_maskl[4][rawkey1 >> 25]
	   | key_perm_maskl[5][(rawkey1 >> 17) & 0x7f]
	   | key_perm_maskl[6][(rawkey1 >> 9) & 0x7f]
	   | key_perm_maskl[7][(rawkey1 >> 1) & 0x7f];
	k1 = key_perm_maskr[0][rawkey0 >> 25]
	   | key_perm_maskr[1][(rawkey0 >> 17) & 0x7f]
	   | key_perm_maskr[2][(rawkey0 >> 9) & 0x7f]
	   | key_perm_maskr[3][(rawkey0 >> 1) & 0x7f]
	   | key_perm_maskr[4][rawkey1 >> 25]
	   | key_perm_maskr[5][(rawkey1 >> 17) & 0x7f]
	   | key_perm_maskr[6][(rawkey1 >> 9) & 0x7f]
	   | key_perm_maskr[7][(rawkey1 >> 1) & 0x7f];
	/*
	 *	Rotate subkeys and do compression permutation.
	 */
	shifts = 0;
	for (round = 0; round < 16; round++) {
		u_int32_t	t0, t1;

		shifts += key_shifts[round];

		t0 = (k0 << shifts) | (k0 >> (28 - shifts));
		t1 = (k1 << shifts) | (k1 >> (28 - shifts));

		de_keysl[15 - round] =
		en_keysl[round] = comp_maskl[0][(t0 >> 21) & 0x7f]
				| comp_maskl[1][(t0 >> 14) & 0x7f]
				| comp_maskl[2][(t0 >> 7) & 0x7f]
				| comp_maskl[3][t0 & 0x7f]
				| comp_maskl[4][(t1 >> 21) & 0x7f]
				| comp_maskl[5][(t1 >> 14) & 0x7f]
				| comp_maskl[6][(t1 >> 7) & 0x7f]
				| comp_maskl[7][t1 & 0x7f];

		de_keysr[15 - round] =
		en_keysr[round] = comp_maskr[0][(t0 >> 21) & 0x7f]
				| comp_maskr[1][(t0 >> 14) & 0x7f]
				| comp_maskr[2][(t0 >> 7) & 0x7f]
				| comp_maskr[3][t0 & 0x7f]
				| comp_maskr[4][(t1 >> 21) & 0x7f]
				| comp_maskr[5][(t1 >> 14) & 0x7f]
				| comp_maskr[6][(t1 >> 7) & 0x7f]
				| comp_maskr[7][t1 & 0x7f];
	}
}


static int
do_des(	u_int32_t l_in, u_int32_t r_in, u_int32_t *l_out, u_int32_t *r_out, int count)
{
	/* l_in, r_in, l_out, and r_out are in pseudo-"big-endian" format. */
	u_int32_t	l, r, *kl, *kr, *kl1, *kr1;
	u_int32_t	f, r48l, r48r;
	int		round;

	if (count == 0) {
		return 1;
	}
	if (count > 0) {
		/* Encrypting */
		kl1 = en_keysl;
		kr1 = en_keysr;
	} else {
		/* Decrypting */
		count = -count;
		kl1 = de_keysl;
		kr1 = de_keysr;
	}

	/* Do initial permutation (IP). */
	l = ip_maskl[0][l_in >> 24]
	  | ip_maskl[1][(l_in >> 16) & 0xff]
	  | ip_maskl[2][(l_in >> 8) & 0xff]
	  | ip_maskl[3][l_in & 0xff]
	  | ip_maskl[4][r_in >> 24]
	  | ip_maskl[5][(r_in >> 16) & 0xff]
	  | ip_maskl[6][(r_in >> 8) & 0xff]
	  | ip_maskl[7][r_in & 0xff];
	r = ip_maskr[0][l_in >> 24]
	  | ip_maskr[1][(l_in >> 16) & 0xff]
	  | ip_maskr[2][(l_in >> 8) & 0xff]
	  | ip_maskr[3][l_in & 0xff]
	  | ip_maskr[4][r_in >> 24]
	  | ip_maskr[5][(r_in >> 16) & 0xff]
	  | ip_maskr[6][(r_in >> 8) & 0xff]
	  | ip_maskr[7][r_in & 0xff];

	while (count--) {
		/* Do each round. */
		kl = kl1;
		kr = kr1;
		round = 16;
		do {
			/* Expand R to 48 bits (simulate the E-box). */
			r48l	= ((r & 0x00000001) << 23)
				| ((r & 0xf8000000) >> 9)
				| ((r & 0x1f800000) >> 11)
				| ((r & 0x01f80000) >> 13)
				| ((r & 0x001f8000) >> 15);
			r48r	= ((r & 0x0001f800) << 7)
				| ((r & 0x00001f80) << 5)
				| ((r & 0x000001f8) << 3)
				| ((r & 0x0000001f) << 1)
				| ((r & 0x80000000) >> 31);
			/*
			 * Do salting for crypt() and friends, and
			 * XOR with the permuted key.
			 */
			f = (r48l ^ r48r) & saltbits;
			r48l ^= f ^ *kl++;
			r48r ^= f ^ *kr++;
			/*
			 * Do sbox lookups (which shrink it back to 32 bits)
			 * and do the pbox permutation at the same time.
			 */
			f = psbox[0][m_sbox[0][r48l >> 12]]
			  | psbox[1][m_sbox[1][r48l & 0xfff]]
			  | psbox[2][m_sbox[2][r48r >> 12]]
			  | psbox[3][m_sbox[3][r48r & 0xfff]];
			/* Now that we've permuted things, complete f(). */
			f ^= l;
			l = r;
			r = f;
		} while (--round);
		r = l;
		l = f;
	}
	/* Do final permutation (inverse of IP). */
	*l_out	= fp_maskl[0][l >> 24]
		| fp_maskl[1][(l >> 16) & 0xff]
		| fp_maskl[2][(l >> 8) & 0xff]
		| fp_maskl[3][l & 0xff]
		| fp_maskl[4][r >> 24]
		| fp_maskl[5][(r >> 16) & 0xff]
		| fp_maskl[6][(r >> 8) & 0xff]
		| fp_maskl[7][r & 0xff];
	*r_out	= fp_maskr[0][l >> 24]
		| fp_maskr[1][(l >> 16) & 0xff]
		| fp_maskr[2][(l >> 8) & 0xff]
		| fp_maskr[3][l & 0xff]
		| fp_maskr[4][r >> 24]
		| fp_maskr[5][(r >> 16) & 0xff]
		| fp_maskr[6][(r >> 8) & 0xff]
		| fp_maskr[7][r & 0xff];
	return(0);
}


#if 0
static int
des_cipher(const char *in, char *out, u_int32_t salt, int count)
{
	u_int32_t	l_out, r_out, rawl, rawr;
	int		retval;
	union {
		u_int32_t	*ui32;
		const char	*c;
	} trans;

	des_init();

	setup_salt(salt);

	trans.c = in;
	rawl = ntohl(*trans.ui32++);
	rawr = ntohl(*trans.ui32);

	retval = do_des(rawl, rawr, &l_out, &r_out, count);

	trans.c = out;
	*trans.ui32++ = htonl(l_out);
	*trans.ui32 = htonl(r_out);
	return(retval);
}
#endif


void
setkey(const char *key)
{
	int	i, j;
	u_int32_t	packed_keys[2];
	u_char	*p;

	p = (u_char *) packed_keys;

	for (i = 0; i < 8; i++) {
		p[i] = 0;
		for (j = 0; j < 8; j++)
			if (*key++ & 1)
				p[i] |= bits8[j];
	}
	des_setkey((char *)p);
}


void
encrypt(char *block, int flag)
{
	u_int32_t	io[2];
	u_char	*p;
	int	i, j;

	des_init();

	setup_salt(0L);
	p = (u_char*)block;
	for (i = 0; i < 2; i++) {
		io[i] = 0L;
		for (j = 0; j < 32; j++)
			if (*p++ & 1)
				io[i] |= bits32[j];
	}
	do_des(io[0], io[1], io, io + 1, flag ? -1 : 1);
	for (i = 0; i < 2; i++)
		for (j = 0; j < 32; j++)
			block[(i << 5) | j] = (io[i] & bits32[j]) ? 1 : 0;
}

char *__des_crypt(const unsigned char *key, const unsigned char *setting)
{
	u_int32_t	count, salt, l, r0, r1, keybuf[2];
	u_char		*p, *q;
	static char	output[21];

	des_init();

	/*
	 * Copy the key, shifting each character up by one bit
	 * and padding with zeros.
	 */
	q = (u_char *)keybuf;
	while (q - (u_char *)keybuf - 8) {
		*q++ = *key << 1;
		if (*(q - 1))
			key++;
	}
	des_setkey((char *)keybuf);

#if 0
	if (*setting == _PASSWORD_EFMT1) {
		int		i;
		/*
		 * "new"-style:
		 *	setting - underscore, 4 bytes of count, 4 bytes of salt
		 *	key - unlimited characters
		 */
		for (i = 1, count = 0L; i < 5; i++)
			count |= ascii_to_bin(setting[i]) << ((i - 1) * 6);

		for (i = 5, salt = 0L; i < 9; i++)
			salt |= ascii_to_bin(setting[i]) << ((i - 5) * 6);

		while (*key) {
			/*
			 * Encrypt the key with itself.
			 */
			if (des_cipher((char *)keybuf, (char *)keybuf, 0L, 1))
				return(NULL);
			/*
			 * And XOR with the next 8 characters of the key.
			 */
			q = (u_char *)keybuf;
			while (q - (u_char *)keybuf - 8 && *key)
				*q++ ^= *key++ << 1;

			des_setkey((char *)keybuf);
		}
		strncpy(output, setting, 9);

		/*
		 * Double check that we weren't given a short setting.
		 * If we were, the above code will probably have created
		 * wierd values for count and salt, but we don't really care.
		 * Just make sure the output string doesn't have an extra
		 * NUL in it.
		 */
		output[9] = '\0';
		p = (u_char *)output + strlen(output);
	} else
#endif
	{
		/*
		 * "old"-style:
		 *	setting - 2 bytes of salt
		 *	key - up to 8 characters
		 */
		count = 25;

		salt = (ascii_to_bin(setting[1]) << 6)
		     |  ascii_to_bin(setting[0]);

		output[0] = setting[0];
		/*
		 * If the encrypted password that the salt was extracted from
		 * is only 1 character long, the salt will be corrupted.  We
		 * need to ensure that the output string doesn't have an extra
		 * NUL in it!
		 */
		output[1] = setting[1] ? setting[1] : output[0];

		p = (u_char *)output + 2;
	}
	setup_salt(salt);
	/*
	 * Do it.
	 */
	if (do_des(0L, 0L, &r0, &r1, (int)count))
		return(NULL);
	/*
	 * Now encode the result...
	 */
	l = (r0 >> 8);
	*p++ = ascii64[(l >> 18) & 0x3f];
	*p++ = ascii64[(l >> 12) & 0x3f];
	*p++ = ascii64[(l >> 6) & 0x3f];
	*p++ = ascii64[l & 0x3f];

	l = (r0 << 16) | ((r1 >> 16) & 0xffff);
	*p++ = ascii64[(l >> 18) & 0x3f];
	*p++ = ascii64[(l >> 12) & 0x3f];
	*p++ = ascii64[(l >> 6) & 0x3f];
	*p++ = ascii64[l & 0x3f];

	l = r1 << 2;
	*p++ = ascii64[(l >> 12) & 0x3f];
	*p++ = ascii64[(l >> 6) & 0x3f];
	*p++ = ascii64[l & 0x3f];
	*p = 0;

	return(output);
}