/*-
 * Copyright (c) 1991, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Matt Bishop of Dartmouth College.
 *
 * The United States Government has rights in this work pursuant
 * to contract no. NAG 2-680 between the National Aeronautics and
 * Space Administration and Dartmouth College.
 *
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. 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.
 *
 * @(#) Copyright (c) 1991, 1993 The Regents of the University of California.  All rights reserved.
 * @(#)bdes.c   8.1 (Berkeley) 6/6/93
 * $FreeBSD: src/secure/usr.bin/bdes/bdes.c,v 1.11 2009/11/03 18:40:42 jhb Exp $
 */

/*
 * BDES -- DES encryption package for Berkeley Software Distribution 4.4
 * options:
 *      -a      key is in ASCII
 *      -b      use ECB (electronic code book) mode
 *      -d      invert (decrypt) input
 *      -f b    use b-bit CFB (cipher feedback) mode
 *      -F b    use b-bit CFB (cipher feedback) alternative mode
 *      -k key  use key as the cryptographic key
 *      -m b    generate a MAC of length b
 *      -o b    use b-bit OFB (output feedback) mode
 *      -p      don't reset the parity bit
 *      -v v    use v as the initialization vector (ignored for ECB)
 * note: the last character of the last block is the integer indicating
 * how many characters of that block are to be output
 *
 * Author: Matt Bishop
 *         Department of Mathematics and Computer Science
 *         Dartmouth College
 *         Hanover, NH  03755
 * Email:  Matt.Bishop@dartmouth.edu
 *         ...!decvax!dartvax!Matt.Bishop
 *
 * See Technical Report PCS-TR91-158, Department of Mathematics and Computer
 * Science, Dartmouth College, for a detailed description of the implemen-
 * tation and differences between it and Sun's.  The DES is described in
 * FIPS PUB 46, and the modes in FIPS PUB 81 (see either the manual page
 * or the technical report for a complete reference).
 */

#include <sys/types.h>

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <openssl/des.h>

/*
 * BSD and System V systems offer special library calls that do
 * block moves and fills, so if possible we take advantage of them
 */
#define MEMCPY(dest,src,len)    bcopy((src),(dest),(len))
#define MEMZERO(dest,len)       bzero((dest),(len))

#define DES_XFORM(buf)                                                  \
                DES_ecb_encrypt(buf, buf, &schedule,                    \
                    mode == MODE_ENCRYPT ? DES_ENCRYPT : DES_DECRYPT);

/*
 * this does an error-checking write
 */
#define READ(buf, n)    fread(buf, sizeof(char), n, stdin)
#define WRITE(buf,n)                                            \
                if (fwrite(buf, sizeof(char), n, stdout) != n)  \
                        warnx("fwrite error at %d", n);

/*
 * global variables and related macros
 */
#define KEY_DEFAULT             0       /* interpret radix of key from key */
#define KEY_ASCII               1       /* key is in ASCII characters */
int keybase = KEY_DEFAULT;              /* how to interpret the key */

enum {                                  /* encrypt, decrypt, authenticate */
        MODE_ENCRYPT, MODE_DECRYPT, MODE_AUTHENTICATE
} mode = MODE_ENCRYPT;

enum {                                  /* ecb, cbc, cfb, cfba, ofb? */
        ALG_ECB, ALG_CBC, ALG_CFB, ALG_OFB, ALG_CFBA
} alg = ALG_CBC;

DES_cblock ivec;                                /* initialization vector */

char bits[] = {                         /* used to extract bits from a char */
        '\200', '\100', '\040', '\020', '\010', '\004', '\002', '\001'
};

int inverse;                            /* 0 to encrypt, 1 to decrypt */
int macbits = -1;                       /* number of bits in authentication */
int fbbits = -1;                        /* number of feedback bits */
int pflag;                              /* 1 to preserve parity bits */

DES_key_schedule schedule;              /* expanded DES key */

static void ecbenc(void);
static void ecbdec(void);
static void cbcenc(void);
static void cbcdec(void);
static void cfbenc(void);
static void cfbdec(void);
static void cfbaenc(void);
static void cfbadec(void);
static void ofbenc(void);
static void ofbdec(void);

static void cbcauth(void);
static void cfbauth(void);

static void cvtkey(DES_cblock, char *);
static int setbits(char *, int);
static void makekey(DES_cblock *);
static int tobinhex(char, int);

static void usage(void);

int
main(int argc, char *argv[])
{
        extern char *optarg;            /* argument to option if any */
        int i;                          /* counter in a for loop */
        char *p;                        /* used to obtain the key */
        DES_cblock msgbuf;              /* I/O buffer */
        int kflag;                      /* command-line encryption key */

        setproctitle("-");              /* Hide command-line arguments */

        /* initialize the initialization vector */
        MEMZERO(ivec, 8);

        /* process the argument list */
        kflag = 0;
        while ((i = getopt(argc, argv, "abdF:f:k:m:o:pv:")) != -1)
                switch(i) {
                case 'a':               /* key is ASCII */
                        keybase = KEY_ASCII;
                        break;
                case 'b':               /* use ECB mode */
                        alg = ALG_ECB;
                        break;
                case 'd':               /* decrypt */
                        mode = MODE_DECRYPT;
                        break;
                case 'F':               /* use alternative CFB mode */
                        alg = ALG_CFBA;
                        if ((fbbits = setbits(optarg, 7)) > 56 || fbbits == 0)
                                errx(1, "-F: number must be 1-56 inclusive");
                        else if (fbbits == -1)
                                errx(1, "-F: number must be a multiple of 7");
                        break;
                case 'f':               /* use CFB mode */
                        alg = ALG_CFB;
                        if ((fbbits = setbits(optarg, 8)) > 64 || fbbits == 0)
                                errx(1, "-f: number must be 1-64 inclusive");
                        else if (fbbits == -1)
                                errx(1, "-f: number must be a multiple of 8");
                        break;
                case 'k':               /* encryption key */
                        kflag = 1;
                        cvtkey(msgbuf, optarg);
                        break;
                case 'm':               /* number of bits for MACing */
                        mode = MODE_AUTHENTICATE;
                        if ((macbits = setbits(optarg, 1)) > 64)
                                errx(1, "-m: number must be 0-64 inclusive");
                        break;
                case 'o':               /* use OFB mode */
                        alg = ALG_OFB;
                        if ((fbbits = setbits(optarg, 8)) > 64 || fbbits == 0)
                                errx(1, "-o: number must be 1-64 inclusive");
                        else if (fbbits == -1)
                                errx(1, "-o: number must be a multiple of 8");
                        break;
                case 'p':               /* preserve parity bits */
                        pflag = 1;
                        break;
                case 'v':               /* set initialization vector */
                        cvtkey(ivec, optarg);
                        break;
                default:                /* error */
                        usage();
                }

        if (!kflag) {
                /*
                 * if the key's not ASCII, assume it is
                 */
                keybase = KEY_ASCII;
                /*
                 * get the key
                 */
                p = getpass("Enter key: ");
                /*
                 * copy it, nul-padded, into the key area
                 */
                cvtkey(msgbuf, p);
        }

        makekey(&msgbuf);
        inverse = (alg == ALG_CBC || alg == ALG_ECB) && mode == MODE_DECRYPT;

        switch(alg) {
        case ALG_CBC:
                switch(mode) {
                case MODE_AUTHENTICATE: /* authenticate using CBC mode */
                        cbcauth();
                        break;
                case MODE_DECRYPT:      /* decrypt using CBC mode */
                        cbcdec();
                        break;
                case MODE_ENCRYPT:      /* encrypt using CBC mode */
                        cbcenc();
                        break;
                }
                break;
        case ALG_CFB:
                switch(mode) {
                case MODE_AUTHENTICATE: /* authenticate using CFB mode */
                        cfbauth();
                        break;
                case MODE_DECRYPT:      /* decrypt using CFB mode */
                        cfbdec();
                        break;
                case MODE_ENCRYPT:      /* encrypt using CFB mode */
                        cfbenc();
                        break;
                }
                break;
        case ALG_CFBA:
                switch(mode) {
                case MODE_AUTHENTICATE: /* authenticate using CFBA mode */
                        errx(1, "can't authenticate with CFBA mode");
                        break;
                case MODE_DECRYPT:      /* decrypt using CFBA mode */
                        cfbadec();
                        break;
                case MODE_ENCRYPT:      /* encrypt using CFBA mode */
                        cfbaenc();
                        break;
                }
                break;
        case ALG_ECB:
                switch(mode) {
                case MODE_AUTHENTICATE: /* authenticate using ECB mode */
                        errx(1, "can't authenticate with ECB mode");
                        break;
                case MODE_DECRYPT:      /* decrypt using ECB mode */
                        ecbdec();
                        break;
                case MODE_ENCRYPT:      /* encrypt using ECB mode */
                        ecbenc();
                        break;
                }
                break;
        case ALG_OFB:
                switch(mode) {
                case MODE_AUTHENTICATE: /* authenticate using OFB mode */
                        errx(1, "can't authenticate with OFB mode");
                        break;
                case MODE_DECRYPT:      /* decrypt using OFB mode */
                        ofbdec();
                        break;
                case MODE_ENCRYPT:      /* encrypt using OFB mode */
                        ofbenc();
                        break;
                }
                break;
        }
        return (0);
}

/*
 * map a hex character to an integer
 */
static int
tobinhex(char c, int radix)
{
        switch(c) {
        case '0':               return(0x0);
        case '1':               return(0x1);
        case '2':               return(radix > 2 ? 0x2 : -1);
        case '3':               return(radix > 3 ? 0x3 : -1);
        case '4':               return(radix > 4 ? 0x4 : -1);
        case '5':               return(radix > 5 ? 0x5 : -1);
        case '6':               return(radix > 6 ? 0x6 : -1);
        case '7':               return(radix > 7 ? 0x7 : -1);
        case '8':               return(radix > 8 ? 0x8 : -1);
        case '9':               return(radix > 9 ? 0x9 : -1);
        case 'A': case 'a':     return(radix > 10 ? 0xa : -1);
        case 'B': case 'b':     return(radix > 11 ? 0xb : -1);
        case 'C': case 'c':     return(radix > 12 ? 0xc : -1);
        case 'D': case 'd':     return(radix > 13 ? 0xd : -1);
        case 'E': case 'e':     return(radix > 14 ? 0xe : -1);
        case 'F': case 'f':     return(radix > 15 ? 0xf : -1);
        }
        /*
         * invalid character
         */
        return(-1);
}

/*
 * convert the key to a bit pattern
 */
static void
cvtkey(DES_cblock obuf, char *ibuf)
{
        int i, j;                       /* counter in a for loop */
        int nbuf[64];                   /* used for hex/key translation */

        /*
         * just switch on the key base
         */
        switch(keybase) {
        case KEY_ASCII:                 /* ascii to integer */
                (void)strncpy(obuf, ibuf, 8);
                return;
        case KEY_DEFAULT:               /* tell from context */
                /*
                 * leading '0x' or '0X' == hex key
                 */
                if (ibuf[0] == '0' && (ibuf[1] == 'x' || ibuf[1] == 'X')) {
                        ibuf = &ibuf[2];
                        /*
                         * now translate it, bombing on any illegal hex digit
                         */
                        for (i = 0; i < 16 && ibuf[i]; i++)
                                if ((nbuf[i] = tobinhex(ibuf[i], 16)) == -1)
                                        warnx("bad hex digit in key");
                        while (i < 16)
                                nbuf[i++] = 0;
                        for (i = 0; i < 8; i++)
                                obuf[i] =
                                    ((nbuf[2*i]&0xf)<<4) | (nbuf[2*i+1]&0xf);
                        /* preserve parity bits */
                        pflag = 1;
                        return;
                }
                /*
                 * leading '0b' or '0B' == binary key
                 */
                if (ibuf[0] == '0' && (ibuf[1] == 'b' || ibuf[1] == 'B')) {
                        ibuf = &ibuf[2];
                        /*
                         * now translate it, bombing on any illegal binary digit
                         */
                        for (i = 0; i < 16 && ibuf[i]; i++)
                                if ((nbuf[i] = tobinhex(ibuf[i], 2)) == -1)
                                        warnx("bad binary digit in key");
                        while (i < 64)
                                nbuf[i++] = 0;
                        for (i = 0; i < 8; i++)
                                for (j = 0; j < 8; j++)
                                        obuf[i] = (obuf[i]<<1)|nbuf[8*i+j];
                        /* preserve parity bits */
                        pflag = 1;
                        return;
                }
                /*
                 * no special leader -- ASCII
                 */
                (void)strncpy(obuf, ibuf, 8);
        }
}

/*
 * convert an ASCII string into a decimal number:
 * 1. must be between 0 and 64 inclusive
 * 2. must be a valid decimal number
 * 3. must be a multiple of mult
 */
static int
setbits(char *s, int mult)
{
        char *p;                        /* pointer in a for loop */
        int n = 0;                      /* the integer collected */

        /*
         * skip white space
         */
        while (isspace(*s))
                s++;
        /*
         * get the integer
         */
        for (p = s; *p; p++) {
                if (isdigit(*p))
                        n = n * 10 + *p - '0';
                else {
                        warnx("bad decimal digit in MAC length");
                }
        }
        /*
         * be sure it's a multiple of mult
         */
        return((n % mult != 0) ? -1 : n);
}

/*****************
 * DES FUNCTIONS *
 *****************/
/*
 * This sets the DES key and (if you're using the deszip version)
 * the direction of the transformation.  This uses the Sun
 * to map the 64-bit key onto the 56 bits that the key schedule
 * generation routines use: the old way, which just uses the user-
 * supplied 64 bits as is, and the new way, which resets the parity
 * bit to be the same as the low-order bit in each character.  The
 * new way generates a greater variety of key schedules, since many
 * systems set the parity (high) bit of each character to 0, and the
 * DES ignores the low order bit of each character.
 */
static void
makekey(DES_cblock *buf)
{
        int i, j;                               /* counter in a for loop */
        int par;                                /* parity counter */

        /*
         * if the parity is not preserved, flip it
         */
        if (!pflag) {
                for (i = 0; i < 8; i++) {
                        par = 0;
                        for (j = 1; j < 8; j++)
                                if ((bits[j] & (*buf)[i]) != 0)
                                        par++;
                        if ((par & 0x01) == 0x01)
                                (*buf)[i] &= 0x7f;
                        else
                                (*buf)[i] = ((*buf)[i] & 0x7f) | 0x80;
                }
        }

        DES_set_odd_parity(buf);
        DES_set_key(buf, &schedule);
}

/*
 * This encrypts using the Electronic Code Book mode of DES
 */
static void
ecbenc(void)
{
        int n;                          /* number of bytes actually read */
        int bn;                         /* block number */
        DES_cblock msgbuf;              /* I/O buffer */

        for (bn = 0; (n = READ(msgbuf,  8)) == 8; bn++) {
                /*
                 * do the transformation
                 */
                DES_XFORM(&msgbuf);
                WRITE(&msgbuf, 8);
        }
        /*
         * at EOF or last block -- in either case, the last byte contains
         * the character representation of the number of bytes in it
         */
        bn++;
        MEMZERO(&msgbuf[n], 8 - n);
        msgbuf[7] = n;
        DES_XFORM(&msgbuf);
        WRITE(&msgbuf, 8);

}

/*
 * This decrypts using the Electronic Code Book mode of DES
 */
static void
ecbdec(void)
{
        int n;                  /* number of bytes actually read */
        int c;                  /* used to test for EOF */
        int bn;                 /* block number */
        DES_cblock msgbuf;              /* I/O buffer */

        for (bn = 1; (n = READ(msgbuf, 8)) == 8; bn++) {
                /*
                 * do the transformation
                 */
                DES_XFORM(&msgbuf);
                /*
                 * if the last one, handle it specially
                 */
                if ((c = getchar()) == EOF) {
                        n = msgbuf[7];
                        if (n < 0 || n > 7)
                                warnx("decryption failed (block corrupt) at %d",
                                    bn);
                }
                else
                        (void)ungetc(c, stdin);
                WRITE(msgbuf, n);
        }
        if (n > 0)
                warnx("decryption failed (incomplete block) at %d", bn);
}

/*
 * This encrypts using the Cipher Block Chaining mode of DES
 */
static void
cbcenc(void)
{
        int n;                  /* number of bytes actually read */
        int bn;                 /* block number */
        DES_cblock msgbuf;      /* I/O buffer */

        /*
         * do the transformation
         */
        for (bn = 1; (n = READ(msgbuf, 8)) == 8; bn++) {
                for (n = 0; n < 8; n++)
                        msgbuf[n] ^= ivec[n];
                DES_XFORM(&msgbuf);
                MEMCPY(ivec, msgbuf, 8);
                WRITE(msgbuf, 8);
        }
        /*
         * at EOF or last block -- in either case, the last byte contains
         * the character representation of the number of bytes in it
         */
        bn++;
        MEMZERO(&msgbuf[n], 8 - n);
        msgbuf[7] = n;
        for (n = 0; n < 8; n++)
                msgbuf[n] ^= ivec[n];
        DES_XFORM(&msgbuf);
        WRITE(msgbuf, 8);

}

/*
 * This decrypts using the Cipher Block Chaining mode of DES
 */
static void
cbcdec(void)
{
        int n;                  /* number of bytes actually read */
        DES_cblock msgbuf;      /* I/O buffer */
        DES_cblock ibuf;        /* temp buffer for initialization vector */
        int c;                  /* used to test for EOF */
        int bn;                 /* block number */

        for (bn = 0; (n = READ(msgbuf, 8)) == 8; bn++) {
                /*
                 * do the transformation
                 */
                MEMCPY(ibuf, msgbuf, 8);
                DES_XFORM(&msgbuf);
                for (c = 0; c < 8; c++)
                        msgbuf[c] ^= ivec[c];
                MEMCPY(ivec, ibuf, 8);
                /*
                 * if the last one, handle it specially
                 */
                if ((c = getchar()) == EOF) {
                        n = msgbuf[7];
                        if (n < 0 || n > 7)
                                warnx("decryption failed (block corrupt) at %d",
                                    bn);
                }
                else
                        (void)ungetc(c, stdin);
                WRITE(msgbuf, n);
        }
        if (n > 0)
                warnx("decryption failed (incomplete block) at %d", bn);
}

/*
 * This authenticates using the Cipher Block Chaining mode of DES
 */
static void
cbcauth(void)
{
        int n, j;               /* number of bytes actually read */
        DES_cblock msgbuf;              /* I/O buffer */
        DES_cblock encbuf;              /* encryption buffer */

        /*
         * do the transformation
         * note we DISCARD the encrypted block;
         * we only care about the last one
         */
        while ((n = READ(msgbuf, 8)) == 8) {
                for (n = 0; n < 8; n++)
                        encbuf[n] = msgbuf[n] ^ ivec[n];
                DES_XFORM(&encbuf);
                MEMCPY(ivec, encbuf, 8);
        }
        /*
         * now compute the last one, right padding with '\0' if need be
         */
        if (n > 0) {
                MEMZERO(&msgbuf[n], 8 - n);
                for (n = 0; n < 8; n++)
                        encbuf[n] = msgbuf[n] ^ ivec[n];
                DES_XFORM(&encbuf);
        }
        /*
         * drop the bits
         * we write chars until fewer than 7 bits,
         * and then pad the last one with 0 bits
         */
        for (n = 0; macbits > 7; n++, macbits -= 8)
                (void)putchar(encbuf[n]);
        if (macbits > 0) {
                msgbuf[0] = 0x00;
                for (j = 0; j < macbits; j++)
                        msgbuf[0] |= encbuf[n] & bits[j];
                (void)putchar(msgbuf[0]);
        }
}

/*
 * This encrypts using the Cipher FeedBack mode of DES
 */
static void
cfbenc(void)
{
        int n;                  /* number of bytes actually read */
        int nbytes;             /* number of bytes to read */
        int bn;                 /* block number */
        char ibuf[8];           /* input buffer */
        DES_cblock msgbuf;              /* encryption buffer */

        /*
         * do things in bytes, not bits
         */
        nbytes = fbbits / 8;
        /*
         * do the transformation
         */
        for (bn = 1; (n = READ(ibuf, nbytes)) == nbytes; bn++) {
                MEMCPY(msgbuf, ivec, 8);
                DES_XFORM(&msgbuf);
                for (n = 0; n < 8 - nbytes; n++)
                        ivec[n] = ivec[n+nbytes];
                for (n = 0; n < nbytes; n++)
                        ivec[8 - nbytes + n] = ibuf[n] ^ msgbuf[n];
                WRITE(&ivec[8 - nbytes], nbytes);
        }
        /*
         * at EOF or last block -- in either case, the last byte contains
         * the character representation of the number of bytes in it
         */
        bn++;
        MEMZERO(&ibuf[n], nbytes - n);
        ibuf[nbytes - 1] = n;
        MEMCPY(msgbuf, ivec, 8);
        DES_XFORM(&msgbuf);
        for (n = 0; n < nbytes; n++)
                ibuf[n] ^= msgbuf[n];
        WRITE(ibuf, nbytes);
}

/*
 * This decrypts using the Cipher Block Chaining mode of DES
 */
static void
cfbdec(void)
{
        int n;                  /* number of bytes actually read */
        int c;                  /* used to test for EOF */
        int nbytes;             /* number of bytes to read */
        int bn;                 /* block number */
        char ibuf[8];           /* input buffer */
        char obuf[8];           /* output buffer */
        DES_cblock msgbuf;              /* encryption buffer */

        /*
         * do things in bytes, not bits
         */
        nbytes = fbbits / 8;
        /*
         * do the transformation
         */
        for (bn = 1; (n = READ(ibuf, nbytes)) == nbytes; bn++) {
                MEMCPY(msgbuf, ivec, 8);
                DES_XFORM(&msgbuf);
                for (c = 0; c < 8 - nbytes; c++)
                        ivec[c] = ivec[c + nbytes];
                for (c = 0; c < nbytes; c++) {
                        ivec[8 - nbytes + c] = ibuf[c];
                        obuf[c] = ibuf[c] ^ msgbuf[c];
                }
                /*
                 * if the last one, handle it specially
                 */
                if ((c = getchar()) == EOF) {
                        n = obuf[nbytes-1];
                        if (n < 0 || n > nbytes-1)
                                warnx("decryption failed (block corrupt) at %d",
                                    bn);
                }
                else
                        (void)ungetc(c, stdin);
                WRITE(obuf, n);
        }
        if (n > 0)
                warnx("decryption failed (incomplete block) at %d", bn);
}

/*
 * This encrypts using the alternative Cipher FeedBack mode of DES
 */
static void
cfbaenc(void)
{
        int n;                  /* number of bytes actually read */
        int nbytes;             /* number of bytes to read */
        int bn;                 /* block number */
        char ibuf[8];           /* input buffer */
        char obuf[8];           /* output buffer */
        DES_cblock msgbuf;              /* encryption buffer */

        /*
         * do things in bytes, not bits
         */
        nbytes = fbbits / 7;
        /*
         * do the transformation
         */
        for (bn = 1; (n = READ(ibuf, nbytes)) == nbytes; bn++) {
                MEMCPY(msgbuf, ivec, 8);
                DES_XFORM(&msgbuf);
                for (n = 0; n < 8 - nbytes; n++)
                        ivec[n] = ivec[n + nbytes];
                for (n = 0; n < nbytes; n++)
                        ivec[8 - nbytes + n] = (ibuf[n] ^ msgbuf[n]) | 0x80;
                for (n = 0; n < nbytes; n++)
                        obuf[n] = ivec[8 - nbytes + n] & 0x7f;
                WRITE(obuf, nbytes);
        }
        /*
         * at EOF or last block -- in either case, the last byte contains
         * the character representation of the number of bytes in it
         */
        bn++;
        MEMZERO(&ibuf[n], nbytes - n);
        ibuf[nbytes - 1] = ('0' + n)|0200;
        MEMCPY(msgbuf, ivec, 8);
        DES_XFORM(&msgbuf);
        for (n = 0; n < nbytes; n++)
                ibuf[n] ^= msgbuf[n];
        WRITE(ibuf, nbytes);
}

/*
 * This decrypts using the alternative Cipher Block Chaining mode of DES
 */
static void
cfbadec(void)
{
        int n;                  /* number of bytes actually read */
        int c;                  /* used to test for EOF */
        int nbytes;             /* number of bytes to read */
        int bn;                 /* block number */
        char ibuf[8];           /* input buffer */
        char obuf[8];           /* output buffer */
        DES_cblock msgbuf;              /* encryption buffer */

        /*
         * do things in bytes, not bits
         */
        nbytes = fbbits / 7;
        /*
         * do the transformation
         */
        for (bn = 1; (n = READ(ibuf, nbytes)) == nbytes; bn++) {
                MEMCPY(msgbuf, ivec, 8);
                DES_XFORM(&msgbuf);
                for (c = 0; c < 8 - nbytes; c++)
                        ivec[c] = ivec[c + nbytes];
                for (c = 0; c < nbytes; c++) {
                        ivec[8 - nbytes + c] = ibuf[c] | 0x80;
                        obuf[c] = (ibuf[c] ^ msgbuf[c]) & 0x7f;
                }
                /*
                 * if the last one, handle it specially
                 */
                if ((c = getchar()) == EOF) {
                        if ((n = (obuf[nbytes-1] - '0')) < 0
                                                || n > nbytes-1)
                                warnx("decryption failed (block corrupt) at %d",
                                    bn);
                }
                else
                        (void)ungetc(c, stdin);
                WRITE(obuf, n);
        }
        if (n > 0)
                warnx("decryption failed (incomplete block) at %d", bn);
}


/*
 * This encrypts using the Output FeedBack mode of DES
 */
static void
ofbenc(void)
{
        int n;                  /* number of bytes actually read */
        int c;                  /* used to test for EOF */
        int nbytes;             /* number of bytes to read */
        int bn;                 /* block number */
        char ibuf[8];           /* input buffer */
        char obuf[8];           /* output buffer */
        DES_cblock msgbuf;              /* encryption buffer */

        /*
         * do things in bytes, not bits
         */
        nbytes = fbbits / 8;
        /*
         * do the transformation
         */
        for (bn = 1; (n = READ(ibuf, nbytes)) == nbytes; bn++) {
                MEMCPY(msgbuf, ivec, 8);
                DES_XFORM(&msgbuf);
                for (n = 0; n < 8 - nbytes; n++)
                        ivec[n] = ivec[n + nbytes];
                for (n = 0; n < nbytes; n++) {
                        ivec[8 - nbytes + n] = msgbuf[n];
                        obuf[n] = ibuf[n] ^ msgbuf[n];
                }
                WRITE(obuf, nbytes);
        }
        /*
         * at EOF or last block -- in either case, the last byte contains
         * the character representation of the number of bytes in it
         */
        bn++;
        MEMZERO(&ibuf[n], nbytes - n);
        ibuf[nbytes - 1] = n;
        MEMCPY(msgbuf, ivec, 8);
        DES_XFORM(&msgbuf);
        for (c = 0; c < nbytes; c++)
                ibuf[c] ^= msgbuf[c];
        WRITE(ibuf, nbytes);
}

/*
 * This decrypts using the Output Block Chaining mode of DES
 */
static void
ofbdec(void)
{
        int n;                  /* number of bytes actually read */
        int c;                  /* used to test for EOF */
        int nbytes;             /* number of bytes to read */
        int bn;                 /* block number */
        char ibuf[8];           /* input buffer */
        char obuf[8];           /* output buffer */
        DES_cblock msgbuf;              /* encryption buffer */

        /*
         * do things in bytes, not bits
         */
        nbytes = fbbits / 8;
        /*
         * do the transformation
         */
        for (bn = 1; (n = READ(ibuf, nbytes)) == nbytes; bn++) {
                MEMCPY(msgbuf, ivec, 8);
                DES_XFORM(&msgbuf);
                for (c = 0; c < 8 - nbytes; c++)
                        ivec[c] = ivec[c + nbytes];
                for (c = 0; c < nbytes; c++) {
                        ivec[8 - nbytes + c] = msgbuf[c];
                        obuf[c] = ibuf[c] ^ msgbuf[c];
                }
                /*
                 * if the last one, handle it specially
                 */
                if ((c = getchar()) == EOF) {
                        n = obuf[nbytes-1];
                        if (n < 0 || n > nbytes-1)
                                warnx("decryption failed (block corrupt) at %d",
                                    bn);
                }
                else
                        (void)ungetc(c, stdin);
                /*
                 * dump it
                 */
                WRITE(obuf, n);
        }
        if (n > 0)
                warnx("decryption failed (incomplete block) at %d", bn);
}

/*
 * This authenticates using the Cipher FeedBack mode of DES
 */
static void
cfbauth(void)
{
        int n, j;               /* number of bytes actually read */
        int nbytes;             /* number of bytes to read */
        char ibuf[8];           /* input buffer */
        DES_cblock msgbuf;      /* encryption buffer */

        /*
         * do things in bytes, not bits
         */
        nbytes = fbbits / 8;
        /*
         * do the transformation
         */
        while ((n = READ(ibuf, nbytes)) == nbytes) {
                MEMCPY(msgbuf, ivec, 8);
                DES_XFORM(&msgbuf);
                for (n = 0; n < 8 - nbytes; n++)
                        ivec[n] = ivec[n + nbytes];
                for (n = 0; n < nbytes; n++)
                        ivec[8 - nbytes + n] = ibuf[n] ^ msgbuf[n];
        }
        /*
         * at EOF or last block -- in either case, the last byte contains
         * the character representation of the number of bytes in it
         */
        MEMZERO(&ibuf[n], nbytes - n);
        ibuf[nbytes - 1] = '0' + n;
        MEMCPY(msgbuf, ivec, 8);
        DES_XFORM(&msgbuf);
        for (n = 0; n < nbytes; n++)
                ibuf[n] ^= msgbuf[n];
        /*
         * drop the bits
         * we write chars until fewer than 7 bits,
         * and then pad the last one with 0 bits
         */
        for (n = 0; macbits > 7; n++, macbits -= 8)
                (void)putchar(msgbuf[n]);
        if (macbits > 0) {
                msgbuf[0] = 0x00;
                for (j = 0; j < macbits; j++)
                        msgbuf[0] |= msgbuf[n] & bits[j];
                (void)putchar(msgbuf[0]);
        }
}

/*
 * message about usage
 */
static void
usage(void)
{
        (void)fprintf(stderr, "%s\n",
"usage: bdes [-abdp] [-F N] [-f N] [-k key] [-m N] [-o N] [-v vector]");
        exit(1);
}