/*
 * The contents of this file are subject to the AOLserver Public License
 * Version 1.1 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * http://aolserver.com/.
 *
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 * the License for the specific language governing rights and limitations
 * under the License.
 *
 * The Original Code is AOLserver Code and related documentation
 * distributed by AOL.
 * 
 * The Initial Developer of the Original Code is America Online,
 * Inc. Portions created by AOL are Copyright (C) 1999 America Online,
 * Inc. All Rights Reserved.
 *
 * Alternatively, the contents of this file may be used under the terms
 * of the GNU General Public License (the "GPL"), in which case the
 * provisions of GPL are applicable instead of those above.  If you wish
 * to allow use of your version of this file only under the terms of the
 * GPL and not to allow others to use your version of this file under the
 * License, indicate your decision by deleting the provisions above and
 * replace them with the notice and other provisions required by the GPL.
 * If you do not delete the provisions above, a recipient may use your
 * version of this file under either the License or the GPL.
 */


static const char *RCSID = "@(#) $Header: /cvsroot/aolserver/aolserver/nsd/crypt.c,v 1.4 2001/03/27 00:14:44 jgdavidson Exp $, compiled: " __DATE__ " " __TIME__;

#include "nsd.h"

/*
 * This program implements the Proposed Federal Information Processing Data
 * Encryption Standard. See Federal Register, March 17, 1975 (40FR12134)
 */

/*
 * Initial permutation,
 */
static const char     IP[] = {
    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,
};

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

/*
 * Permuted-choice 1 from the key bits to yield C and D. Note that bits
 * 8,16... are left out: They are intended for a parity check.
 */
static const char    PC1_C[] = {
    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,
};

static const char     PC1_D[] = {
    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,
};

/*
 * Sequence of shifts used for the key schedule.
 */
static const char     shifts[] = {
    1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1,
};

/*
 * Permuted-choice 2, to pick out the bits from the CD array that generate
 * the key schedule.
 */
static const char     PC2_C[] = {
    14, 17, 11, 24, 1, 5,
    3, 28, 15, 6, 21, 10,
    23, 19, 12, 4, 26, 8,
    16, 7, 27, 20, 13, 2,
};

static const char     PC2_D[] = {
    41, 52, 31, 37, 47, 55,
    30, 40, 51, 45, 33, 48,
    44, 49, 39, 56, 34, 53,
    46, 42, 50, 36, 29, 32,
};

/*
 * The following structure maitains the key schedule.
 */

struct sched {
    /*
     * The C and D arrays used to calculate the key schedule.
     */

    char     C[28];
    char     D[28];

    /*
     * The key schedule. Generated from the key.
     */
    char     KS[16][48];

    /*
     * The E bit-selection table.
     */
    char     E[48];
};

static const char     e[] = {
    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,
};

/*
 * Set up the key schedule from the key.
 */

static void
setkey_private(struct sched *sp, const char *key)
{
    register int    i, j, k;
    int             t;

    /*
     * First, generate C and D by permuting the key.  The low order bit of
     * each 8-bit char is not used, so C and D are only 28 bits apiece.
     */
    for (i = 0; i < 28; i++) {
        sp->C[i] = key[PC1_C[i] - 1];
        sp->D[i] = key[PC1_D[i] - 1];
    }

    /*
     * To generate Ki, rotate C and D according to schedule and pick up a
     * permutation using PC2.
     */
    for (i = 0; i < 16; i++) {

        /*
         * rotate.
         */
        for (k = 0; k < shifts[i]; k++) {
            t = sp->C[0];
            for (j = 0; j < 28 - 1; j++)
                sp->C[j] = sp->C[j + 1];
            sp->C[27] = t;
            t = sp->D[0];
            for (j = 0; j < 28 - 1; j++)
                sp->D[j] = sp->D[j + 1];
            sp->D[27] = t;
        }

        /*
         * get Ki. Note C and D are concatenated.
         */
        for (j = 0; j < 24; j++) {
            sp->KS[i][j] = sp->C[PC2_C[j] - 1];
            sp->KS[i][j + 24] = sp->D[PC2_D[j] - 28 - 1];
        }
    }

    for (i = 0; i < 48; i++)
        sp->E[i] = e[i];
}

/*
 * The 8 selection functions. For some reason, they give a 0-origin index,
 * unlike everything else.
 */
static const char     S[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 },
};

/*
 * P is a permutation on the selected combination of the current L and key.
 */
static const char     P[] = {
    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,
};

/*
 * The payoff: encrypt a block.
 */

static void
encrypt_private(struct sched *sp, char *block, int edflag)
{
    /*
     * The current block, divided into 2 halves.
     */
    char     L[64], *R = L + 32;
    char     tempL[32];
    char     f[32];

    /*
     * The combination of the key and the input, before selection.
     */
    char     preS[48];

    int             i, ii;
    register int    t, j, k;

    /*
     * First, permute the bits in the input
     */
    for (j = 0; j < 64; j++)
        L[j] = block[IP[j] - 1];

    /*
     * Perform an encryption operation 16 times.
     */
    for (ii = 0; ii < 16; ii++) {

        /*
         * Set direction
         */
        if (edflag)
            i = 15 - ii;
        else
            i = ii;

        /*
         * Save the R array, which will be the new L.
         */
        for (j = 0; j < 32; j++)
            tempL[j] = R[j];

        /*
         * Expand R to 48 bits using the E selector; exclusive-or with the
         * current key bits.
         */
        for (j = 0; j < 48; j++)
            preS[j] = R[sp->E[j] - 1] ^ sp->KS[i][j];

        /*
         * The pre-select bits are now considered in 8 groups of 6 bits each.
         * The 8 selection functions map these 6-bit quantities into 4-bit
         * quantities and the results permuted to make an f(R, K). The
         * indexing into the selection functions is peculiar; it could be
         * simplified by rewriting the tables.
         */
        for (j = 0; j < 8; j++) {
            t = 6 * j;
            k = S[j][(preS[t + 0] << 5) +
                (preS[t + 1] << 3) +
                (preS[t + 2] << 2) +
                (preS[t + 3] << 1) +
                (preS[t + 4] << 0) +
                (preS[t + 5] << 4)];
            t = 4 * j;
            f[t + 0] = (k >> 3) & 01;
            f[t + 1] = (k >> 2) & 01;
            f[t + 2] = (k >> 1) & 01;
            f[t + 3] = (k >> 0) & 01;
        }

        /*
         * The new R is L ^ f(R, K). The f here has to be permuted first,
         * though.
         */
        for (j = 0; j < 32; j++)
            R[j] = L[j] ^ f[P[j] - 1];

        /*
         * Finally, the new L (the original R) is copied back.
         */
        for (j = 0; j < 32; j++)
            L[j] = tempL[j];
    }

    /*
     * The output L and R are reversed.
     */
    for (j = 0; j < 32; j++) {
        t = L[j];
        L[j] = R[j];
        R[j] = t;
    }

    /*
     * The final output gets the inverse permutation of the very original.
     */
    for (j = 0; j < 64; j++)
        block[j] = L[FP[j] - 1];
}


char           *
Ns_Encrypt(pw, salt, iobuf)
    char           *pw;
    char           *salt;
    char            iobuf[];
{
    register int    i, j, c;
    int             temp;
    char            block[66];
    struct sched    s;

    for (i = 0; i < 66; i++)
        block[i] = 0;
    for (i = 0; (c = *pw) && i < 64; pw++) {
        for (j = 0; j < 7; j++, i++)
            block[i] = (c >> (6 - j)) & 01;
        i++;
    }

    setkey_private(&s, block);

    for (i = 0; i < 66; i++)
        block[i] = 0;

    for (i = 0; i < 2; i++) {
        c = *salt++;
        iobuf[i] = c;
        if (c > 'Z')
            c -= 6;
        if (c > '9')
            c -= 7;
        c -= '.';
        for (j = 0; j < 6; j++) {
            if ((c >> j) & 01) {
                temp = s.E[6 * i + j];
                s.E[6 * i + j] = s.E[6 * i + j + 24];
                s.E[6 * i + j + 24] = temp;
            }
        }
    }

    for (i = 0; i < 25; i++)
        encrypt_private(&s, block, 0);

    for (i = 0; i < 11; i++) {
        c = 0;
        for (j = 0; j < 6; j++) {
            c <<= 1;
            c |= block[6 * i + j];
        }
        c += '.';
        if (c > '9')
            c += 7;
        if (c > 'Z')
            c += 6;
        iobuf[i + 2] = c;
    }
    iobuf[i + 2] = 0;
    if (iobuf[1] == 0)
        iobuf[1] = iobuf[0];

    return (iobuf);
}
