/*
 * FreeSec: libcrypt
 *
 * Copyright (C) 1994 David Burren
 * 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. Neither the name(s) of the author(s) 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(S) 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(S) 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.
 *
 * NOTE:
 * This file has a static version of des_setkey() so that crypt.o exports
 * only the crypt() interface. This is required to make binaries linked
 * against crypt.o exportable or re-exportable from the USA.
 */

#include <sys/types.h>
#include <string.h>

#define _PASSWORD_EFMT1 '_'

unsigned long int md_htonl(unsigned long int x);
unsigned long int md_ntohl(unsigned long int x);

static unsigned char    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 unsigned char    inv_key_perm[64];
static unsigned char    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 unsigned char    key_shifts[16] = {
    1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1
};

static unsigned char    inv_comp_perm[56];
static unsigned char    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 unsigned char    u_sbox[8][64];
static unsigned char    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 unsigned char    un_pbox[32];
static unsigned char    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 unsigned int 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 unsigned char    bits8[8] = { 0x80, 0x40, 0x20, 0x10, 0x08, 0x04, 0x02, 0x01 };

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

static unsigned char    ascii64[] =
     "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
/*    0000000000111111111122222222223333333333444444444455555555556666 */
/*    0123456789012345678901234567890123456789012345678901234567890123 */

static __inline int
ascii_to_bin(ch)
    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()
{
    int i, j, b, k, inbit, obit;
    unsigned int    *p, *il, *ir, *fl, *fr;

    old_rawkey0 = old_rawkey1 = 0;
    saltbits = 0;
    old_salt = 0;
    bits24 = (bits28 = 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++) {
        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]) = 0;
            *(ir = &ip_maskr[k][i]) = 0;
            *(fl = &fp_maskl[k][i]) = 0;
            *(fr = &fp_maskr[k][i]) = 0;
            for (j = 0; j < 8; j++) {
                inbit = 8 * k + j;
                if (i & bits8[j]) {
                    if ((obit = init_perm[inbit]) < 32)
                        *il |= bits32[obit];
                    else
                        *ir |= bits32[obit-32];
                    if ((obit = final_perm[inbit]) < 32)
                        *fl |= bits32[obit];
                    else
                        *fr |= bits32[obit - 32];
                }
            }
        }
        for (i = 0; i < 128; i++) {
            *(il = &key_perm_maskl[k][i]) = 0;
            *(ir = &key_perm_maskr[k][i]) = 0;
            for (j = 0; j < 7; j++) {
                inbit = 8 * k + j;
                if (i & 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]) = 0;
            *(ir = &comp_maskr[k][i]) = 0;
            for (j = 0; j < 7; j++) {
                inbit = 7 * k + j;
                if (i & 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]) = 0;
            for (j = 0; j < 8; j++) {
                if (i & bits8[j])
                    *p |= bits32[un_pbox[8 * b + j]];
            }
        }

    des_initialised = 1;
}

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

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

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

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

    if (!des_initialised)
        des_init();

    rawkey0 = md_ntohl(*(unsigned int *) key);
    rawkey1 = md_ntohl(*(unsigned int *) (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++) {
        unsigned int    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(l_in, r_in, l_out, r_out, count)
    unsigned int l_in, r_in, *l_out, *r_out;
    int count;
{
    /*
     *  l_in, r_in, l_out, and r_out are in pseudo-"big-endian" format.
     */
    unsigned int    l, r, *kl, *kr, *kl1, *kr1;
    unsigned int    f = 0, 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(in, out, salt, count)
    const char *in;
    char *out;
    int salt;
    int count;
{
    unsigned int l_out, r_out, rawl, rawr;
    unsigned int x[2];
    int retval;

    if (!des_initialised)
        des_init();

    setup_salt(salt);

    memcpy(x, in, sizeof x);
    rawl = md_ntohl(x[0]);
    rawr = md_ntohl(x[1]);
    retval = do_des(rawl, rawr, &l_out, &r_out, count);

    x[0] = md_htonl(l_out);
    x[1] = md_htonl(r_out);
    memcpy(out, x, sizeof x);
    return(retval);
}

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

    if (!des_initialised)
        des_init();

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

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

        for (i = 5, salt = 0; 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, 0, 1))
                return(NULL);
            /*
             * And XOR with the next 8 characters of the key.
             */
            q = (unsigned char *) keybuf;
            while (((q - (unsigned char *) keybuf) < sizeof(keybuf)) &&
                    *key)
                *q++ ^= *key++ << 1;

            if (des_setkey((char *) keybuf))
                return(NULL);
        }
        strncpy((char *)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 = output + strlen((const char *)output);
    } else {
        /*
         * "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(0, 0, &r0, &r1, 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((char *)output);
}