crypt-des.c

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/*
 * FreeSec: libcrypt for NetBSD
 *
 * contrib/pgcrypto/crypt-des.c
 *
 * 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.
 *
 * $FreeBSD: src/secure/lib/libcrypt/crypt-des.c,v 1.12 1999/09/20 12:39:20 markm Exp $
 *
 * This is an original implementation of the DES and the crypt(3) interfaces
 * by David Burren <[email protected]>.
 *
 * 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 uint32's (ie. the CPU is not picky about
 *  alignment).
 */

#include "postgres.h"

#include "px-crypt.h"

/* for ntohl/htonl */
#include <netinet/in.h>
#include <arpa/inet.h>

#define _PASSWORD_EFMT1 '_'

static const char _crypt_a64[] =
"./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";

static uint8 IP[64] = {
    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
};

static uint8 inv_key_perm[64];
static uint8 u_key_perm[56];
static uint8 key_perm[56] = {
    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 uint8 key_shifts[16] = {
    1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1
};

static uint8 inv_comp_perm[56];
static uint8 comp_perm[48] = {
    14, 17, 11, 24, 1, 5, 3, 28, 15, 6, 21, 10,
    23, 19, 12, 4, 26, 8, 16, 7, 27, 20, 13, 2,
    41, 52, 31, 37, 47, 55, 30, 40, 51, 45, 33, 48,
    44, 49, 39, 56, 34, 53, 46, 42, 50, 36, 29, 32
};

/*
 *  No E box is used, as it's replaced by some ANDs, shifts, and ORs.
 */

static uint8 u_sbox[8][64];
static uint8 sbox[8][64] = {
    {
        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
    },
    {
        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
    },
    {
        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
    },
    {
        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
    },
    {
        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
    },
    {
        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
    },
    {
        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
    },
    {
        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 uint8 un_pbox[32];
static uint8 pbox[32] = {
    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 uint32 _crypt_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 uint8 _crypt_bits8[8] = {0x80, 0x40, 0x20, 0x10, 0x08, 0x04, 0x02, 0x01};

static uint32 saltbits;
static long old_salt;
static uint32 *bits28,
           *bits24;
static uint8 init_perm[64],
            final_perm[64];
static uint32 en_keysl[16],
            en_keysr[16];
static uint32 de_keysl[16],
            de_keysr[16];
static int  des_initialised = 0;
static uint8 m_sbox[4][4096];
static uint32 psbox[4][256];
static uint32 ip_maskl[8][256],
            ip_maskr[8][256];
static uint32 fp_maskl[8][256],
            fp_maskr[8][256];
static uint32 key_perm_maskl[8][128],
            key_perm_maskr[8][128];
static uint32 comp_maskl[8][128],
            comp_maskr[8][128];
static uint32 old_rawkey0,
            old_rawkey1;

static inline 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)
{
    int         i,
                j,
                b,
                k,
                inbit,
                obit;
    uint32     *p,
               *il,
               *ir,
               *fl,
               *fr;

    old_rawkey0 = old_rawkey1 = 0L;
    saltbits = 0L;
    old_salt = 0L;
    bits24 = (bits28 = _crypt_bits32 + 4) + 4;

    /*
     * Invert the S-boxes, reordering the input bits.
     */
    for (i = 0; i < 8; i++)
        for (j = 0; j < 64; j++)
        {
            b = (j & 0x20) | ((j & 1) << 4) | ((j >> 1) & 0xf);
            u_sbox[i][j] = sbox[i][b];
        }

    /*
     * Convert the inverted S-boxes into 4 arrays of 8 bits. Each will handle
     * 12 bits of the S-box input.
     */
    for (b = 0; b < 4; b++)
        for (i = 0; i < 64; i++)
            for (j = 0; j < 64; j++)
                m_sbox[b][(i << 6) | j] =
                    (u_sbox[(b << 1)][i] << 4) |
                    u_sbox[(b << 1) + 1][j];

    /*
     * Set up the initial & final permutations into a useful form, and
     * initialise the inverted key permutation.
     */
    for (i = 0; i < 64; i++)
    {
        init_perm[final_perm[i] = IP[i] - 1] = i;
        inv_key_perm[i] = 255;
    }

    /*
     * Invert the key permutation and initialise the inverted key compression
     * permutation.
     */
    for (i = 0; i < 56; i++)
    {
        u_key_perm[i] = key_perm[i] - 1;
        inv_key_perm[key_perm[i] - 1] = i;
        inv_comp_perm[i] = 255;
    }

    /*
     * Invert the key compression permutation.
     */
    for (i = 0; i < 48; i++)
        inv_comp_perm[comp_perm[i] - 1] = i;

    /*
     * Set up the OR-mask arrays for the initial and final permutations, and
     * for the key initial and compression permutations.
     */
    for (k = 0; k < 8; k++)
    {
        for (i = 0; i < 256; i++)
        {
            *(il = &ip_maskl[k][i]) = 0L;
            *(ir = &ip_maskr[k][i]) = 0L;
            *(fl = &fp_maskl[k][i]) = 0L;
            *(fr = &fp_maskr[k][i]) = 0L;
            for (j = 0; j < 8; j++)
            {
                inbit = 8 * k + j;
                if (i & _crypt_bits8[j])
                {
                    if ((obit = init_perm[inbit]) < 32)
                        *il |= _crypt_bits32[obit];
                    else
                        *ir |= _crypt_bits32[obit - 32];
                    if ((obit = final_perm[inbit]) < 32)
                        *fl |= _crypt_bits32[obit];
                    else
                        *fr |= _crypt_bits32[obit - 32];
                }
            }
        }
        for (i = 0; i < 128; i++)
        {
            *(il = &key_perm_maskl[k][i]) = 0L;
            *(ir = &key_perm_maskr[k][i]) = 0L;
            for (j = 0; j < 7; j++)
            {
                inbit = 8 * k + j;
                if (i & _crypt_bits8[j + 1])
                {
                    if ((obit = inv_key_perm[inbit]) == 255)
                        continue;
                    if (obit < 28)
                        *il |= bits28[obit];
                    else
                        *ir |= bits28[obit - 28];
                }
            }
            *(il = &comp_maskl[k][i]) = 0L;
            *(ir = &comp_maskr[k][i]) = 0L;
            for (j = 0; j < 7; j++)
            {
                inbit = 7 * k + j;
                if (i & _crypt_bits8[j + 1])
                {
                    if ((obit = inv_comp_perm[inbit]) == 255)
                        continue;
                    if (obit < 24)
                        *il |= bits24[obit];
                    else
                        *ir |= bits24[obit - 24];
                }
            }
        }
    }

    /*
     * Invert the P-box permutation, and convert into OR-masks for handling
     * the output of the S-box arrays setup above.
     */
    for (i = 0; i < 32; i++)
        un_pbox[pbox[i] - 1] = i;

    for (b = 0; b < 4; b++)
        for (i = 0; i < 256; i++)
        {
            *(p = &psbox[b][i]) = 0L;
            for (j = 0; j < 8; j++)
            {
                if (i & _crypt_bits8[j])
                    *p |= _crypt_bits32[un_pbox[8 * b + j]];
            }
        }

    des_initialised = 1;
}

static void
setup_salt(long salt)
{
    uint32      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 int
des_setkey(const char *key)
{
    uint32      k0,
                k1,
                rawkey0,
                rawkey1;
    int         shifts,
                round;

    if (!des_initialised)
        des_init();

    rawkey0 = ntohl(*(const uint32 *) key);
    rawkey1 = ntohl(*(const uint32 *) (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 (0);
    }
    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++)
    {
        uint32      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];
    }
    return (0);
}

static int
do_des(uint32 l_in, uint32 r_in, uint32 *l_out, uint32 *r_out, int count)
{
    /*
     * l_in, r_in, l_out, and r_out are in pseudo-"big-endian" format.
     */
    uint32      l,
                r,
               *kl,
               *kr,
               *kl1,
               *kr1;
    uint32      f,
                r48l,
                r48r;
    int         round;

    if (count == 0)
        return (1);
    else 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;
        while (round--)
        {
            /*
             * 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;
        }
        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);
}

static int
des_cipher(const char *in, char *out, long salt, int count)
{
    uint32      buffer[2];
    uint32      l_out,
                r_out,
                rawl,
                rawr;
    int         retval;

    if (!des_initialised)
        des_init();

    setup_salt(salt);

    /* copy data to avoid assuming input is word-aligned */
    memcpy(buffer, in, sizeof(buffer));

    rawl = ntohl(buffer[0]);
    rawr = ntohl(buffer[1]);

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

    buffer[0] = htonl(l_out);
    buffer[1] = htonl(r_out);

    /* copy data to avoid assuming output is word-aligned */
    memcpy(out, buffer, sizeof(buffer));

    return (retval);
}

char *
px_crypt_des(const char *key, const char *setting)
{
    int         i;
    uint32      count,
                salt,
                l,
                r0,
                r1,
                keybuf[2];
    char       *p;
    uint8      *q;
    static char output[21];

    if (!des_initialised)
        des_init();


    /*
     * Copy the key, shifting each character up by one bit and padding with
     * zeros.
     */
    q = (uint8 *) keybuf;
    while (q - (uint8 *) keybuf - 8)
    {
        *q++ = *key << 1;
        if (*key != '\0')
            key++;
    }
    if (des_setkey((char *) keybuf))
        return (NULL);

#ifndef DISABLE_XDES
    if (*setting == _PASSWORD_EFMT1)
    {
        /*
         * "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 = (uint8 *) keybuf;
            while (q - (uint8 *) keybuf - 8 && *key)
                *q++ ^= *key++ << 1;

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

        /*
         * Double check that we weren't given a short setting. If we were, the
         * above code will probably have created weird 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 = output + strlen(output);
    }
    else
#endif   /* !DISABLE_XDES */
    {
        /*
         * "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 = output + 2;
    }
    setup_salt(salt);

    /*
     * Do it.
     */
    if (do_des(0L, 0L, &r0, &r1, count))
        return (NULL);

    /*
     * Now encode the result...
     */
    l = (r0 >> 8);
    *p++ = _crypt_a64[(l >> 18) & 0x3f];
    *p++ = _crypt_a64[(l >> 12) & 0x3f];
    *p++ = _crypt_a64[(l >> 6) & 0x3f];
    *p++ = _crypt_a64[l & 0x3f];

    l = (r0 << 16) | ((r1 >> 16) & 0xffff);
    *p++ = _crypt_a64[(l >> 18) & 0x3f];
    *p++ = _crypt_a64[(l >> 12) & 0x3f];
    *p++ = _crypt_a64[(l >> 6) & 0x3f];
    *p++ = _crypt_a64[l & 0x3f];

    l = r1 << 2;
    *p++ = _crypt_a64[(l >> 12) & 0x3f];
    *p++ = _crypt_a64[(l >> 6) & 0x3f];
    *p++ = _crypt_a64[l & 0x3f];
    *p = 0;

    return (output);
}