xref: /src/lib/libcrypt/crypt.c

/*	$NetBSD: crypt.c,v 1.33 2011/12/28 03:13:09 christos Exp $	*/

/*
 * Copyright (c) 1989, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Tom Truscott.
 *
 * 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 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 REGENTS 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 REGENTS 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.
 */

#include <sys/cdefs.h>
#if !defined(lint)
#if 0
static char sccsid[] = "@(#)crypt.c	8.1.1.1 (Berkeley) 8/18/93";
#else
__RCSID("$NetBSD: crypt.c,v 1.33 2011/12/28 03:13:09 christos Exp $");
#endif
#endif /* not lint */

#include <limits.h>
#include <pwd.h>
#include <stdlib.h>
#include <unistd.h>
#if defined(DEBUG) || defined(MAIN) || defined(UNIT_TEST)
#include <stdio.h>
#endif

#include "crypt.h"

/*
 * UNIX password, and DES, encryption.
 * By Tom Truscott, trt (at) rti.rti.org,
 * from algorithms by Robert W. Baldwin and James Gillogly.
 *
 * References:
 * "Mathematical Cryptology for Computer Scientists and Mathematicians,"
 * by Wayne Patterson, 1987, ISBN 0-8476-7438-X.
 *
 * "Password Security: A Case History," R. Morris and Ken Thompson,
 * Communications of the ACM, vol. 22, pp. 594-597, Nov. 1979.
 *
 * "DES will be Totally Insecure within Ten Years," M.E. Hellman,
 * IEEE Spectrum, vol. 16, pp. 32-39, July 1979.
 */

/* =====  Configuration ==================== */

/*
 * define "MUST_ALIGN" if your compiler cannot load/store
 * long integers at arbitrary (e.g. odd) memory locations.
 * (Either that or never pass unaligned addresses to des_cipher!)
 */
#if !defined(__vax__) && !defined(__i386__)
#define	MUST_ALIGN
#endif

#ifdef CHAR_BITS
#if CHAR_BITS != 8
	#error C_block structure assumes 8 bit characters
#endif
#endif

/*
 * define "B64" to be the declaration for a 64 bit integer.
 * XXX this feature is currently unused, see "endian" comment below.
 */
#if defined(cray)
#define	B64	long
#endif
#if defined(convex)
#define	B64	long long
#endif

/*
 * define "LARGEDATA" to get faster permutations, by using about 72 kilobytes
 * of lookup tables.  This speeds up des_setkey() and des_cipher(), but has
 * little effect on crypt().
 */
#if defined(notdef)
#define	LARGEDATA
#endif

/* compile with "-DSTATIC=void" when profiling */
#ifndef STATIC
#define	STATIC	static void
#endif

/* ==================================== */

/*
 * Cipher-block representation (Bob Baldwin):
 *
 * DES operates on groups of 64 bits, numbered 1..64 (sigh).  One
 * representation is to store one bit per byte in an array of bytes.  Bit N of
 * the NBS spec is stored as the LSB of the Nth byte (index N-1) in the array.
 * Another representation stores the 64 bits in 8 bytes, with bits 1..8 in the
 * first byte, 9..16 in the second, and so on.  The DES spec apparently has
 * bit 1 in the MSB of the first byte, but that is particularly noxious so we
 * bit-reverse each byte so that bit 1 is the LSB of the first byte, bit 8 is
 * the MSB of the first byte.  Specifically, the 64-bit input data and key are
 * converted to LSB format, and the output 64-bit block is converted back into
 * MSB format.
 *
 * DES operates internally on groups of 32 bits which are expanded to 48 bits
 * by permutation E and shrunk back to 32 bits by the S boxes.  To speed up
 * the computation, the expansion is applied only once, the expanded
 * representation is maintained during the encryption, and a compression
 * permutation is applied only at the end.  To speed up the S-box lookups,
 * the 48 bits are maintained as eight 6 bit groups, one per byte, which
 * directly feed the eight S-boxes.  Within each byte, the 6 bits are the
 * most significant ones.  The low two bits of each byte are zero.  (Thus,
 * bit 1 of the 48 bit E expansion is stored as the "4"-valued bit of the
 * first byte in the eight byte representation, bit 2 of the 48 bit value is
 * the "8"-valued bit, and so on.)  In fact, a combined "SPE"-box lookup is
 * used, in which the output is the 64 bit result of an S-box lookup which
 * has been permuted by P and expanded by E, and is ready for use in the next
 * iteration.  Two 32-bit wide tables, SPE[0] and SPE[1], are used for this
 * lookup.  Since each byte in the 48 bit path is a multiple of four, indexed
 * lookup of SPE[0] and SPE[1] is simple and fast.  The key schedule and
 * "salt" are also converted to this 8*(6+2) format.  The SPE table size is
 * 8*64*8 = 4K bytes.
 *
 * To speed up bit-parallel operations (such as XOR), the 8 byte
 * representation is "union"ed with 32 bit values "i0" and "i1", and, on
 * machines which support it, a 64 bit value "b64".  This data structure,
 * "C_block", has two problems.  First, alignment restrictions must be
 * honored.  Second, the byte-order (e.g. little-endian or big-endian) of
 * the architecture becomes visible.
 *
 * The byte-order problem is unfortunate, since on the one hand it is good
 * to have a machine-independent C_block representation (bits 1..8 in the
 * first byte, etc.), and on the other hand it is good for the LSB of the
 * first byte to be the LSB of i0.  We cannot have both these things, so we
 * currently use the "little-endian" representation and avoid any multi-byte
 * operations that depend on byte order.  This largely precludes use of the
 * 64-bit datatype since the relative order of i0 and i1 are unknown.  It
 * also inhibits grouping the SPE table to look up 12 bits at a time.  (The
 * 12 bits can be stored in a 16-bit field with 3 low-order zeroes and 1
 * high-order zero, providing fast indexing into a 64-bit wide SPE.)  On the
 * other hand, 64-bit datatypes are currently rare, and a 12-bit SPE lookup
 * requires a 128 kilobyte table, so perhaps this is not a big loss.
 *
 * Permutation representation (Jim Gillogly):
 *
 * A transformation is defined by its effect on each of the 8 bytes of the
 * 64-bit input.  For each byte we give a 64-bit output that has the bits in
 * the input distributed appropriately.  The transformation is then the OR
 * of the 8 sets of 64-bits.  This uses 8*256*8 = 16K bytes of storage for
 * each transformation.  Unless LARGEDATA is defined, however, a more compact
 * table is used which looks up 16 4-bit "chunks" rather than 8 8-bit chunks.
 * The smaller table uses 16*16*8 = 2K bytes for each transformation.  This
 * is slower but tolerable, particularly for password encryption in which
 * the SPE transformation is iterated many times.  The small tables total 9K
 * bytes, the large tables total 72K bytes.
 *
 * The transformations used are:
 * IE3264: MSB->LSB conversion, initial permutation, and expansion.
 *	This is done by collecting the 32 even-numbered bits and applying
 *	a 32->64 bit transformation, and then collecting the 32 odd-numbered
 *	bits and applying the same transformation.  Since there are only
 *	32 input bits, the IE3264 transformation table is half the size of
 *	the usual table.
 * CF6464: Compression, final permutation, and LSB->MSB conversion.
 *	This is done by two trivial 48->32 bit compressions to obtain
 *	a 64-bit block (the bit numbering is given in the "CIFP" table)
 *	followed by a 64->64 bit "cleanup" transformation.  (It would
 *	be possible to group the bits in the 64-bit block so that 2
 *	identical 32->32 bit transformations could be used instead,
 *	saving a factor of 4 in space and possibly 2 in time, but
 *	byte-ordering and other complications rear their ugly head.
 *	Similar opportunities/problems arise in the key schedule
 *	transforms.)
 * PC1ROT: MSB->LSB, PC1 permutation, rotate, and PC2 permutation.
 *	This admittedly baroque 64->64 bit transformation is used to
 *	produce the first code (in 8*(6+2) format) of the key schedule.
 * PC2ROT[0]: Inverse PC2 permutation, rotate, and PC2 permutation.
 *	It would be possible to define 15 more transformations, each
 *	with a different rotation, to generate the entire key schedule.
 *	To save space, however, we instead permute each code into the
 *	next by using a transformation that "undoes" the PC2 permutation,
 *	rotates the code, and then applies PC2.  Unfortunately, PC2
 *	transforms 56 bits into 48 bits, dropping 8 bits, so PC2 is not
 *	invertible.  We get around that problem by using a modified PC2
 *	which retains the 8 otherwise-lost bits in the unused low-order
 *	bits of each byte.  The low-order bits are cleared when the
 *	codes are stored into the key schedule.
 * PC2ROT[1]: Same as PC2ROT[0], but with two rotations.
 *	This is faster than applying PC2ROT[0] twice,
 *
 * The Bell Labs "salt" (Bob Baldwin):
 *
 * The salting is a simple permutation applied to the 48-bit result of E.
 * Specifically, if bit i (1 <= i <= 24) of the salt is set then bits i and
 * i+24 of the result are swapped.  The salt is thus a 24 bit number, with
 * 16777216 possible values.  (The original salt was 12 bits and could not
 * swap bits 13..24 with 36..48.)
 *
 * It is possible, but ugly, to warp the SPE table to account for the salt
 * permutation.  Fortunately, the conditional bit swapping requires only
 * about four machine instructions and can be done on-the-fly with about an
 * 8% performance penalty.
 */

typedef union {
	unsigned char b[8];
	struct {
		int32_t	i0;
		int32_t	i1;
	} b32;
#if defined(B64)
	B64	b64;
#endif
} C_block;

/*
 * Convert twenty-four-bit long in host-order
 * to six bits (and 2 low-order zeroes) per char little-endian format.
 */
#define	TO_SIX_BIT(rslt, src) {				\
		C_block cvt;				\
		cvt.b[0] = src; src >>= 6;		\
		cvt.b[1] = src; src >>= 6;		\
		cvt.b[2] = src; src >>= 6;		\
		cvt.b[3] = src;				\
		rslt = (cvt.b32.i0 & 0x3f3f3f3fL) << 2;	\
	}

/*
 * These macros may someday permit efficient use of 64-bit integers.
 */
#define	ZERO(d,d0,d1)			d0 = 0, d1 = 0
#define	LOAD(d,d0,d1,bl)		d0 = (bl).b32.i0, d1 = (bl).b32.i1
#define	LOADREG(d,d0,d1,s,s0,s1)	d0 = s0, d1 = s1
#define	OR(d,d0,d1,bl)			d0 |= (bl).b32.i0, d1 |= (bl).b32.i1
#define	STORE(s,s0,s1,bl)		(bl).b32.i0 = s0, (bl).b32.i1 = s1
#define	DCL_BLOCK(d,d0,d1)		int32_t d0, d1

#if defined(LARGEDATA)
	/* Waste memory like crazy.  Also, do permutations in line */
#define	LGCHUNKBITS	3
#define	CHUNKBITS	(1<<LGCHUNKBITS)
#define	PERM6464(d,d0,d1,cpp,p)				\
	LOAD(d,d0,d1,(p)[(0<<CHUNKBITS)+(cpp)[0]]);		\
	OR (d,d0,d1,(p)[(1<<CHUNKBITS)+(cpp)[1]]);		\
	OR (d,d0,d1,(p)[(2<<CHUNKBITS)+(cpp)[2]]);		\
	OR (d,d0,d1,(p)[(3<<CHUNKBITS)+(cpp)[3]]);		\
	OR (d,d0,d1,(p)[(4<<CHUNKBITS)+(cpp)[4]]);		\
	OR (d,d0,d1,(p)[(5<<CHUNKBITS)+(cpp)[5]]);		\
	OR (d,d0,d1,(p)[(6<<CHUNKBITS)+(cpp)[6]]);		\
	OR (d,d0,d1,(p)[(7<<CHUNKBITS)+(cpp)[7]]);
#define	PERM3264(d,d0,d1,cpp,p)				\
	LOAD(d,d0,d1,(p)[(0<<CHUNKBITS)+(cpp)[0]]);		\
	OR (d,d0,d1,(p)[(1<<CHUNKBITS)+(cpp)[1]]);		\
	OR (d,d0,d1,(p)[(2<<CHUNKBITS)+(cpp)[2]]);		\
	OR (d,d0,d1,(p)[(3<<CHUNKBITS)+(cpp)[3]]);
#else
	/* "small data" */
#define	LGCHUNKBITS	2
#define	CHUNKBITS	(1<<LGCHUNKBITS)
#define	PERM6464(d,d0,d1,cpp,p)				\
	{ C_block tblk; permute(cpp,&tblk,p,8); LOAD (d,d0,d1,tblk); }
#define	PERM3264(d,d0,d1,cpp,p)				\
	{ C_block tblk; permute(cpp,&tblk,p,4); LOAD (d,d0,d1,tblk); }
#endif /* LARGEDATA */

STATIC	init_des(void);
STATIC	init_perm(C_block [64/CHUNKBITS][1<<CHUNKBITS],
		       const unsigned char [64], int, int);
#ifndef LARGEDATA
STATIC	permute(const unsigned char *, C_block *, C_block *, int);
#endif
#ifdef DEBUG
STATIC	prtab(const char *, unsigned char *, int);
#endif


#ifndef LARGEDATA
STATIC
permute(const unsigned char *cp, C_block *out, C_block *p, int chars_in)
{
	DCL_BLOCK(D,D0,D1);
	C_block *tp;
	int t;

	ZERO(D,D0,D1);
	do {
		t = *cp++;
		tp = &p[t&0xf]; OR(D,D0,D1,*tp); p += (1<<CHUNKBITS);
		tp = &p[t>>4];  OR(D,D0,D1,*tp); p += (1<<CHUNKBITS);
	} while (--chars_in > 0);
	STORE(D,D0,D1,*out);
}
#endif /* LARGEDATA */


/* =====  (mostly) Standard DES Tables ==================== */

static const unsigned char IP[] = {	/* initial permutation */
	58, 50, 42, 34, 26, 18, 10,  2,
	60, 52, 44, 36, 28, 20, 12,  4,
	62, 54, 46, 38, 30, 22, 14,  6,
	64, 56, 48, 40, 32, 24, 16,  8,
	57, 49, 41, 33, 25, 17,  9,  1,
	59, 51, 43, 35, 27, 19, 11,  3,
	61, 53, 45, 37, 29, 21, 13,  5,
	63, 55, 47, 39, 31, 23, 15,  7,
};

/* The final permutation is the inverse of IP - no table is necessary */

static const unsigned char ExpandTr[] = {	/* expansion operation */
	32,  1,  2,  3,  4,  5,
	 4,  5,  6,  7,  8,  9,
	 8,  9, 10, 11, 12, 13,
	12, 13, 14, 15, 16, 17,
	16, 17, 18, 19, 20, 21,
	20, 21, 22, 23, 24, 25,
	24, 25, 26, 27, 28, 29,
	28, 29, 30, 31, 32,  1,
};

static const unsigned char PC1[] = {	/* permuted choice table 1 */
	57, 49, 41, 33, 25, 17,  9,
	 1, 58, 50, 42, 34, 26, 18,
	10,  2, 59, 51, 43, 35, 27,
	19, 11,  3, 60, 52, 44, 36,

	63, 55, 47, 39, 31, 23, 15,
	 7, 62, 54, 46, 38, 30, 22,
	14,  6, 61, 53, 45, 37, 29,
	21, 13,  5, 28, 20, 12,  4,
};

static const unsigned char Rotates[] = {/* PC1 rotation schedule */
	1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1,
};

/* note: each "row" of PC2 is left-padded with bits that make it invertible */
static const unsigned char PC2[] = {	/* permuted choice table 2 */
	 9, 18,    14, 17, 11, 24,  1,  5,
	22, 25,     3, 28, 15,  6, 21, 10,
	35, 38,    23, 19, 12,  4, 26,  8,
	43, 54,    16,  7, 27, 20, 13,  2,

	 0,  0,    41, 52, 31, 37, 47, 55,
	 0,  0,    30, 40, 51, 45, 33, 48,
	 0,  0,    44, 49, 39, 56, 34, 53,
	 0,  0,    46, 42, 50, 36, 29, 32,
};

static const unsigned char S[8][64] = {	/* 48->32 bit substitution tables */
					/* S[1]			*/
	{ 14,  4, 13,  1,  2, 15, 11,  8,  3, 10,  6, 12,  5,  9,  0,  7,
	   0, 15,  7,  4, 14,  2, 13,  1, 10,  6, 12, 11,  9,  5,  3,  8,
	   4,  1, 14,  8, 13,  6,  2, 11, 15, 12,  9,  7,  3, 10,  5,  0,
	  15, 12,  8,  2,  4,  9,  1,  7,  5, 11,  3, 14, 10,  0,  6, 13 },
					/* S[2]			*/
	{ 15,  1,  8, 14,  6, 11,  3,  4,  9,  7,  2, 13, 12,  0,  5, 10,
	   3, 13,  4,  7, 15,  2,  8, 14, 12,  0,  1, 10,  6,  9, 11,  5,
	   0, 14,  7, 11, 10,  4, 13,  1,  5,  8, 12,  6,  9,  3,  2, 15,
	  13,  8, 10,  1,  3, 15,  4,  2, 11,  6,  7, 12,  0,  5, 14,  9 },
					/* S[3]			*/
	{ 10,  0,  9, 14,  6,  3, 15,  5,  1, 13, 12,  7, 11,  4,  2,  8,
	  13,  7,  0,  9,  3,  4,  6, 10,  2,  8,  5, 14, 12, 11, 15,  1,
	  13,  6,  4,  9,  8, 15,  3,  0, 11,  1,  2, 12,  5, 10, 14,  7,
	   1, 10, 13,  0,  6,  9,  8,  7,  4, 15, 14,  3, 11,  5,  2, 12 },
					/* S[4]			*/
	{  7, 13, 14,  3,  0,  6,  9, 10,  1,  2,  8,  5, 11, 12,  4, 15,
	  13,  8, 11,  5,  6, 15,  0,  3,  4,  7,  2, 12,  1, 10, 14,  9,
	  10,  6,  9,  0, 12, 11,  7, 13, 15,  1,  3, 14,  5,  2,  8,  4,
	   3, 15,  0,  6, 10,  1, 13,  8,  9,  4,  5, 11, 12,  7,  2, 14 },
					/* S[5]			*/
	{  2, 12,  4,  1,  7, 10, 11,  6,  8,  5,  3, 15, 13,  0, 14,  9,
	  14, 11,  2, 12,  4,  7, 13,  1,  5,  0, 15, 10,  3,  9,  8,  6,
	   4,  2,  1, 11, 10, 13,  7,  8, 15,  9, 12,  5,  6,  3,  0, 14,
	  11,  8, 12,  7,  1, 14,  2, 13,  6, 15,  0,  9, 10,  4,  5,  3 },
					/* S[6]			*/
	{ 12,  1, 10, 15,  9,  2,  6,  8,  0, 13,  3,  4, 14,  7,  5, 11,
	  10, 15,  4,  2,  7, 12,  9,  5,  6,  1, 13, 14,  0, 11,  3,  8,
	   9, 14, 15,  5,  2,  8, 12,  3,  7,  0,  4, 10,  1, 13, 11,  6,
	   4,  3,  2, 12,  9,  5, 15, 10, 11, 14,  1,  7,  6,  0,  8, 13 },
					/* S[7]			*/
	{  4, 11,  2, 14, 15,  0,  8, 13,  3, 12,  9,  7,  5, 10,  6,  1,
	  13,  0, 11,  7,  4,  9,  1, 10, 14,  3,  5, 12,  2, 15,  8,  6,
	   1,  4, 11, 13, 12,  3,  7, 14, 10, 15,  6,  8,  0,  5,  9,  2,
	   6, 11, 13,  8,  1,  4, 10,  7,  9,  5,  0, 15, 14,  2,  3, 12 },
					/* S[8]			*/
	{ 13,  2,  8,  4,  6, 15, 11,  1, 10,  9,  3, 14,  5,  0, 12,  7,
	   1, 15, 13,  8, 10,  3,  7,  4, 12,  5,  6, 11,  0, 14,  9,  2,
	   7, 11,  4,  1,  9, 12, 14,  2,  0,  6, 10, 13, 15,  3,  5,  8,
	   2,  1, 14,  7,  4, 10,  8, 13, 15, 12,  9,  0,  3,  5,  6, 11 }
};

static const unsigned char P32Tr[] = {	/* 32-bit permutation function */
	16,  7, 20, 21,
	29, 12, 28, 17,
	 1, 15, 23, 26,
	 5, 18, 31, 10,
	 2,  8, 24, 14,
	32, 27,  3,  9,
	19, 13, 30,  6,
	22, 11,  4, 25,
};

static const unsigned char CIFP[] = {	/* compressed/interleaved permutation */
	 1,  2,  3,  4,   17, 18, 19, 20,
	 5,  6,  7,  8,   21, 22, 23, 24,
	 9, 10, 11, 12,   25, 26, 27, 28,
	13, 14, 15, 16,   29, 30, 31, 32,

	33, 34, 35, 36,   49, 50, 51, 52,
	37, 38, 39, 40,   53, 54, 55, 56,
	41, 42, 43, 44,   57, 58, 59, 60,
	45, 46, 47, 48,   61, 62, 63, 64,
};

static const unsigned char itoa64[] =		/* 0..63 => ascii-64 */
	"./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";


/* =====  Tables that are initialized at run time  ==================== */


/* Initial key schedule permutation */
static C_block	PC1ROT[64/CHUNKBITS][1<<CHUNKBITS];

/* Subsequent key schedule rotation permutations */
static C_block	PC2ROT[2][64/CHUNKBITS][1<<CHUNKBITS];

/* Initial permutation/expansion table */
static C_block	IE3264[32/CHUNKBITS][1<<CHUNKBITS];

/* Table that combines the S, P, and E operations.  */
static int32_t SPE[2][8][64];

/* compressed/interleaved => final permutation table */
static C_block	CF6464[64/CHUNKBITS][1<<CHUNKBITS];


/* ==================================== */


static C_block	constdatablock;			/* encryption constant */
static char	cryptresult[1+4+4+11+1];	/* encrypted result */

/*
 * We match the behavior of UFC-crypt on systems where "char" is signed by
 * default (the majority), regardless of char's signedness on our system.
 */
static inline int
ascii_to_bin(char ch)
{
	signed char sch = ch;
	int retval;

	if (sch >= 'a')
		retval = sch - ('a' - 38);
	else if (sch >= 'A')
		retval = sch - ('A' - 12);
	else
		retval = sch - '.';

	return retval & 0x3f;
}

/*
 * When we choose to "support" invalid salts, nevertheless disallow those
 * containing characters that would violate the passwd file format.
 */
static inline int
ascii_is_unsafe(char ch)
{
	return !ch || ch == '\n' || ch == ':';
}

/*
 * Return a pointer to static data consisting of the "setting"
 * followed by an encryption produced by the "key" and "setting".
 */
static char *
__crypt(const char *key, const char *setting)
{
	char *encp;
	int32_t i;
	int t;
	int32_t salt;
	int num_iter, salt_size;
	C_block keyblock, rsltblock;

	/* Non-DES encryption schemes hook in here. */
	if (setting[0] == _PASSWORD_NONDES) {
		switch (setting[1]) {
		case '2':
			return (__bcrypt(key, setting));
		case 's':
			return (__crypt_sha1(key, setting));
		case '1':
		default:
			return (__md5crypt(key, setting));
		}
	}

	for (i = 0; i < 8; i++) {
		if ((t = 2*(unsigned char)(*key)) != 0)
			key++;
		keyblock.b[i] = t;
	}
	if (des_setkey((char *)keyblock.b))
		return (NULL);

	encp = &cryptresult[0];
	switch (*setting) {
	case _PASSWORD_EFMT1:
		/*
		 * Involve the rest of the password 8 characters at a time.
		 */
		while (*key) {
			if (des_cipher((char *)(void *)&keyblock,
			    (char *)(void *)&keyblock, 0L, 1))
				return (NULL);
			for (i = 0; i < 8; i++) {
				if ((t = 2*(unsigned char)(*key)) != 0)
					key++;
				keyblock.b[i] ^= t;
			}
			if (des_setkey((char *)keyblock.b))
				return (NULL);
		}

		*encp++ = *setting++;

		/* get iteration count */
		num_iter = 0;
		for (i = 4; --i >= 0; ) {
			int value = ascii_to_bin(setting[i]);
			if (itoa64[value] != setting[i])
				return NULL;
			encp[i] = setting[i];
			num_iter = (num_iter << 6) | value;
		}
		if (num_iter == 0)
			return NULL;
		setting += 4;
		encp += 4;
		salt_size = 4;
		break;
	default:
		num_iter = 25;
		salt_size = 2;
		if (ascii_is_unsafe(setting[0]) || ascii_is_unsafe(setting[1]))
			return NULL;
	}

	salt = 0;
	for (i = salt_size; --i >= 0; ) {
		int value = ascii_to_bin(setting[i]);
		if (salt_size > 2 && itoa64[value] != setting[i])
			return NULL;
		encp[i] = setting[i];
		salt = (salt << 6) | value;
	}
	encp += salt_size;
	if (des_cipher((char *)(void *)&constdatablock,
	    (char *)(void *)&rsltblock, salt, num_iter))
		return (NULL);

	/*
	 * Encode the 64 cipher bits as 11 ascii characters.
	 */
	i = ((int32_t)((rsltblock.b[0]<<8) | rsltblock.b[1])<<8) |
	    rsltblock.b[2];
	encp[3] = itoa64[i&0x3f];	i >>= 6;
	encp[2] = itoa64[i&0x3f];	i >>= 6;
	encp[1] = itoa64[i&0x3f];	i >>= 6;
	encp[0] = itoa64[i];		encp += 4;
	i = ((int32_t)((rsltblock.b[3]<<8) | rsltblock.b[4])<<8) |
	    rsltblock.b[5];
	encp[3] = itoa64[i&0x3f];	i >>= 6;
	encp[2] = itoa64[i&0x3f];	i >>= 6;
	encp[1] = itoa64[i&0x3f];	i >>= 6;
	encp[0] = itoa64[i];		encp += 4;
	i = ((int32_t)((rsltblock.b[6])<<8) | rsltblock.b[7])<<2;
	encp[2] = itoa64[i&0x3f];	i >>= 6;
	encp[1] = itoa64[i&0x3f];	i >>= 6;
	encp[0] = itoa64[i];

	encp[3] = 0;

	return (cryptresult);
}

char *
crypt(const char *key, const char *salt)
{
	char *res = __crypt(key, salt);
	if (res)
		return res;
	/* How do I handle errors ? Return "*0" or "*1" */
	return __UNCONST(salt[0] == '*' && salt[1] == '0' ? "*1" : "*0");
}

/*
 * The Key Schedule, filled in by des_setkey() or setkey().
 */
#define	KS_SIZE	16
static C_block	KS[KS_SIZE];

/*
 * Set up the key schedule from the key.
 */
int
des_setkey(const char *key)
{
	DCL_BLOCK(K, K0, K1);
	C_block *help, *ptabp;
	int i;
	static int des_ready = 0;

	if (!des_ready) {
		init_des();
		des_ready = 1;
	}

	PERM6464(K,K0,K1,(const unsigned char *)key,(C_block *)PC1ROT);
	help = &KS[0];
	STORE(K&~0x03030303L, K0&~0x03030303L, K1, *help);
	for (i = 1; i < 16; i++) {
		help++;
		STORE(K,K0,K1,*help);
		ptabp = (C_block *)PC2ROT[Rotates[i]-1];
		PERM6464(K,K0,K1,(const unsigned char *)help,ptabp);
		STORE(K&~0x03030303L, K0&~0x03030303L, K1, *help);
	}
	return (0);
}

/*
 * Encrypt (or decrypt if num_iter < 0) the 8 chars at "in" with abs(num_iter)
 * iterations of DES, using the given 24-bit salt and the pre-computed key
 * schedule, and store the resulting 8 chars at "out" (in == out is permitted).
 *
 * NOTE: the performance of this routine is critically dependent on your
 * compiler and machine architecture.
 */
int
des_cipher(const char *in, char *out, long salt, int num_iter)
{
	/* variables that we want in registers, most important first */
#if defined(pdp11)
	int j;
#endif
	int32_t L0, L1, R0, R1, k;
	C_block *kp;
	int ks_inc, loop_count;
	C_block B;

	L0 = salt;
	TO_SIX_BIT(salt, L0);	/* convert to 4*(6+2) format */

#if defined(__vax__) || defined(pdp11)
	salt = ~salt;	/* "x &~ y" is faster than "x & y". */
#define	SALT (~salt)
#else
#define	SALT salt
#endif

#if defined(MUST_ALIGN)
	B.b[0] = in[0]; B.b[1] = in[1]; B.b[2] = in[2]; B.b[3] = in[3];
	B.b[4] = in[4]; B.b[5] = in[5]; B.b[6] = in[6]; B.b[7] = in[7];
	LOAD(L,L0,L1,B);
#else
	LOAD(L,L0,L1,*(const C_block *)in);
#endif
	LOADREG(R,R0,R1,L,L0,L1);
	L0 &= 0x55555555L;
	L1 &= 0x55555555L;
	L0 = (L0 << 1) | L1;	/* L0 is the even-numbered input bits */
	R0 &= 0xaaaaaaaaL;
	R1 = (R1 >> 1) & 0x55555555L;
	L1 = R0 | R1;		/* L1 is the odd-numbered input bits */
	STORE(L,L0,L1,B);
	PERM3264(L,L0,L1,B.b,  (C_block *)IE3264);	/* even bits */
	PERM3264(R,R0,R1,B.b+4,(C_block *)IE3264);	/* odd bits */

	if (num_iter >= 0)
	{		/* encryption */
		kp = &KS[0];
		ks_inc  = sizeof(*kp);
	}
	else
	{		/* decryption */
		num_iter = -num_iter;
		kp = &KS[KS_SIZE-1];
		ks_inc  = -(long)sizeof(*kp);
	}

	while (--num_iter >= 0) {
		loop_count = 8;
		do {

#define	SPTAB(t, i) \
	    (*(int32_t *)((unsigned char *)t + i*(sizeof(int32_t)/4)))
#if defined(gould)
			/* use this if B.b[i] is evaluated just once ... */
#define	DOXOR(x,y,i)	x^=SPTAB(SPE[0][i],B.b[i]); y^=SPTAB(SPE[1][i],B.b[i]);
#else
#if defined(pdp11)
			/* use this if your "long" int indexing is slow */
#define	DOXOR(x,y,i)	j=B.b[i]; x^=SPTAB(SPE[0][i],j); y^=SPTAB(SPE[1][i],j);
#else
			/* use this if "k" is allocated to a register ... */
#define	DOXOR(x,y,i)	k=B.b[i]; x^=SPTAB(SPE[0][i],k); y^=SPTAB(SPE[1][i],k);
#endif
#endif

#define	CRUNCH(p0, p1, q0, q1)	\
			k = (q0 ^ q1) & SALT;	\
			B.b32.i0 = k ^ q0 ^ kp->b32.i0;		\
			B.b32.i1 = k ^ q1 ^ kp->b32.i1;		\
			kp = (C_block *)((char *)kp+ks_inc);	\
							\
			DOXOR(p0, p1, 0);		\
			DOXOR(p0, p1, 1);		\
			DOXOR(p0, p1, 2);		\
			DOXOR(p0, p1, 3);		\
			DOXOR(p0, p1, 4);		\
			DOXOR(p0, p1, 5);		\
			DOXOR(p0, p1, 6);		\
			DOXOR(p0, p1, 7);

			CRUNCH(L0, L1, R0, R1);
			CRUNCH(R0, R1, L0, L1);
		} while (--loop_count != 0);
		kp = (C_block *)((char *)kp-(ks_inc*KS_SIZE));


		/* swap L and R */
		L0 ^= R0;  L1 ^= R1;
		R0 ^= L0;  R1 ^= L1;
		L0 ^= R0;  L1 ^= R1;
	}

	/* store the encrypted (or decrypted) result */
	L0 = ((L0 >> 3) & 0x0f0f0f0fL) | ((L1 << 1) & 0xf0f0f0f0L);
	L1 = ((R0 >> 3) & 0x0f0f0f0fL) | ((R1 << 1) & 0xf0f0f0f0L);
	STORE(L,L0,L1,B);
	PERM6464(L,L0,L1,B.b, (C_block *)CF6464);
#if defined(MUST_ALIGN)
	STORE(L,L0,L1,B);
	out[0] = B.b[0]; out[1] = B.b[1]; out[2] = B.b[2]; out[3] = B.b[3];
	out[4] = B.b[4]; out[5] = B.b[5]; out[6] = B.b[6]; out[7] = B.b[7];
#else
	STORE(L,L0,L1,*(C_block *)out);
#endif
	return (0);
}


/*
 * Initialize various tables.  This need only be done once.  It could even be
 * done at compile time, if the compiler were capable of that sort of thing.
 */
STATIC
init_des(void)
{
	int i, j;
	int32_t k;
	int tableno;
	static unsigned char perm[64], tmp32[32];	/* "static" for speed */

	/*
	 * PC1ROT - bit reverse, then PC1, then Rotate, then PC2.
	 */
	for (i = 0; i < 64; i++)
		perm[i] = 0;
	for (i = 0; i < 64; i++) {
		if ((k = PC2[i]) == 0)
			continue;
		k += Rotates[0]-1;
		if ((k%28) < Rotates[0]) k -= 28;
		k = PC1[k];
		if (k > 0) {
			k--;
			k = (k|07) - (k&07);
			k++;
		}
		perm[i] = k;
	}
#ifdef DEBUG
	prtab("pc1tab", perm, 8);
#endif
	init_perm(PC1ROT, perm, 8, 8);

	/*
	 * PC2ROT - PC2 inverse, then Rotate (once or twice), then PC2.
	 */
	for (j = 0; j < 2; j++) {
		unsigned char pc2inv[64];
		for (i = 0; i < 64; i++)
			perm[i] = pc2inv[i] = 0;
		for (i = 0; i < 64; i++) {
			if ((k = PC2[i]) == 0)
				continue;
			pc2inv[k-1] = i+1;
		}
		for (i = 0; i < 64; i++) {
			if ((k = PC2[i]) == 0)
				continue;
			k += j;
			if ((k%28) <= j) k -= 28;
			perm[i] = pc2inv[k];
		}
#ifdef DEBUG
		prtab("pc2tab", perm, 8);
#endif
		init_perm(PC2ROT[j], perm, 8, 8);
	}

	/*
	 * Bit reverse, then initial permutation, then expansion.
	 */
	for (i = 0; i < 8; i++) {
		for (j = 0; j < 8; j++) {
			k = (j < 2)? 0: IP[ExpandTr[i*6+j-2]-1];
			if (k > 32)
				k -= 32;
			else if (k > 0)
				k--;
			if (k > 0) {
				k--;
				k = (k|07) - (k&07);
				k++;
			}
			perm[i*8+j] = k;
		}
	}
#ifdef DEBUG
	prtab("ietab", perm, 8);
#endif
	init_perm(IE3264, perm, 4, 8);

	/*
	 * Compression, then final permutation, then bit reverse.
	 */
	for (i = 0; i < 64; i++) {
		k = IP[CIFP[i]-1];
		if (k > 0) {
			k--;
			k = (k|07) - (k&07);
			k++;
		}
		perm[k-1] = i+1;
	}
#ifdef DEBUG
	prtab("cftab", perm, 8);
#endif
	init_perm(CF6464, perm, 8, 8);

	/*
	 * SPE table
	 */
	for (i = 0; i < 48; i++)
		perm[i] = P32Tr[ExpandTr[i]-1];
	for (tableno = 0; tableno < 8; tableno++) {
		for (j = 0; j < 64; j++)  {
			k = (((j >> 0) &01) << 5)|
			    (((j >> 1) &01) << 3)|
			    (((j >> 2) &01) << 2)|
			    (((j >> 3) &01) << 1)|
			    (((j >> 4) &01) << 0)|
			    (((j >> 5) &01) << 4);
			k = S[tableno][k];
			k = (((k >> 3)&01) << 0)|
			    (((k >> 2)&01) << 1)|
			    (((k >> 1)&01) << 2)|
			    (((k >> 0)&01) << 3);
			for (i = 0; i < 32; i++)
				tmp32[i] = 0;
			for (i = 0; i < 4; i++)
				tmp32[4 * tableno + i] = (k >> i) & 01;
			k = 0;
			for (i = 24; --i >= 0; )
				k = (k<<1) | tmp32[perm[i]-1];
			TO_SIX_BIT(SPE[0][tableno][j], k);
			k = 0;
			for (i = 24; --i >= 0; )
				k = (k<<1) | tmp32[perm[i+24]-1];
			TO_SIX_BIT(SPE[1][tableno][j], k);
		}
	}
}

/*
 * Initialize "perm" to represent transformation "p", which rearranges
 * (perhaps with expansion and/or contraction) one packed array of bits
 * (of size "chars_in" characters) into another array (of size "chars_out"
 * characters).
 *
 * "perm" must be all-zeroes on entry to this routine.
 */
STATIC
init_perm(C_block perm[64/CHUNKBITS][1<<CHUNKBITS], const unsigned char p[64],
    int chars_in, int chars_out)
{
	int i, j, k, l;

	for (k = 0; k < chars_out*8; k++) {	/* each output bit position */
		l = p[k] - 1;		/* where this bit comes from */
		if (l < 0)
			continue;	/* output bit is always 0 */
		i = l>>LGCHUNKBITS;	/* which chunk this bit comes from */
		l = 1<<(l&(CHUNKBITS-1));	/* mask for this bit */
		for (j = 0; j < (1<<CHUNKBITS); j++) {	/* each chunk value */
			if ((j & l) != 0)
				perm[i][j].b[k>>3] |= 1<<(k&07);
		}
	}
}

/*
 * "setkey" routine (for backwards compatibility)
 */
int
setkey(const char *key)
{
	int i, j, k;
	C_block keyblock;

	for (i = 0; i < 8; i++) {
		k = 0;
		for (j = 0; j < 8; j++) {
			k <<= 1;
			k |= (unsigned char)*key++;
		}
		keyblock.b[i] = k;
	}
	return (des_setkey((char *)keyblock.b));
}

/*
 * "encrypt" routine (for backwards compatibility)
 */
int
encrypt(char *block, int flag)
{
	int i, j, k;
	C_block cblock;

	for (i = 0; i < 8; i++) {
		k = 0;
		for (j = 0; j < 8; j++) {
			k <<= 1;
			k |= (unsigned char)*block++;
		}
		cblock.b[i] = k;
	}
	if (des_cipher((char *)&cblock, (char *)&cblock, 0L, (flag ? -1: 1)))
		return (1);
	for (i = 7; i >= 0; i--) {
		k = cblock.b[i];
		for (j = 7; j >= 0; j--) {
			*--block = k&01;
			k >>= 1;
		}
	}
	return (0);
}

#ifdef DEBUG
STATIC
prtab(const char *s, unsigned char *t, int num_rows)
{
	int i, j;

	(void)printf("%s:\n", s);
	for (i = 0; i < num_rows; i++) {
		for (j = 0; j < 8; j++) {
			 (void)printf("%3d", t[i*8+j]);
		}
		(void)printf("\n");
	}
	(void)printf("\n");
}
#endif

#if defined(MAIN) || defined(UNIT_TEST)
#include <err.h>

int
main(int argc, char *argv[])
{
    if (argc < 2)
	errx(1, "Usage: %s password [salt]\n", argv[0]);

    printf("%s\n", crypt(argv[1], (argc > 2) ? argv[2] : argv[1]));
    exit(0);
}
#endif