text_cmds/ed/cbc.c

   1 /* cbc.c: This file contains the encryption routines for the ed line editor */
   2 /*-
   3  * Copyright (c) 1993 The Regents of the University of California.
   4  * All rights reserved.
   5  *
   6  * Copyright (c) 1993 Andrew Moore, Talke Studio.
   7  * All rights reserved.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #include <sys/cdefs.h>
  35 __FBSDID("$FreeBSD: src/bin/ed/cbc.c,v 1.20 2004/04/06 20:06:47 markm Exp $");
  36
  37 #include <sys/types.h>
  38 #include <errno.h>
  39 #include <pwd.h>
  40 #ifdef DES
  41 #include <time.h>
  42 #include <openssl/des.h>
  43 #define ED_DES_INCLUDES
  44 #endif
  45
  46 #include "ed.h"
  47
  48
  49 /*
  50  * BSD and System V systems offer special library calls that do
  51  * block move_liness and fills, so if possible we take advantage of them
  52  */
  53 #define MEMCPY(dest,src,len)    memcpy((dest),(src),(len))
  54 #define MEMZERO(dest,len)       memset((dest), 0, (len))
  55
  56 /* Hide the calls to the primitive encryption routines. */
  57 #define DES_XFORM(buf)                                                  \
  58                 DES_ecb_encrypt(buf, buf, &schedule,                    \
  59                     inverse ? DES_DECRYPT : DES_ENCRYPT);
  60
  61 /*
  62  * read/write - no error checking
  63  */
  64 #define READ(buf, n, fp)        fread(buf, sizeof(char), n, fp)
  65 #define WRITE(buf, n, fp)       fwrite(buf, sizeof(char), n, fp)
  66
  67 /*
  68  * global variables and related macros
  69  */
  70
  71 enum {                                  /* encrypt, decrypt, authenticate */
  72         MODE_ENCRYPT, MODE_DECRYPT, MODE_AUTHENTICATE
  73 } mode = MODE_ENCRYPT;
  74
  75 #ifdef DES
  76 DES_cblock ivec;                        /* initialization vector */
  77 DES_cblock pvec;                        /* padding vector */
  78 #endif
  79
  80 char bits[] = {                         /* used to extract bits from a char */
  81         '\200', '\100', '\040', '\020', '\010', '\004', '\002', '\001'
  82 };
  83
  84 int pflag;                              /* 1 to preserve parity bits */
  85
  86 #ifdef DES
  87 DES_key_schedule schedule;              /* expanded DES key */
  88 #endif
  89
  90 unsigned char des_buf[8];       /* shared buffer for get_des_char/put_des_char */
  91 int des_ct = 0;                 /* count for get_des_char/put_des_char */
  92 int des_n = 0;                  /* index for put_des_char/get_des_char */
  93
  94 /* init_des_cipher: initialize DES */
  95 void
  96 init_des_cipher(void)
  97 {
  98 #ifdef DES
  99         int i;
 100
 101         des_ct = des_n = 0;
 102
 103         /* initialize the initialization vector */
 104         MEMZERO(ivec, 8);
 105
 106         /* initialize the padding vector */
 107         for (i = 0; i < 8; i++)
 108                 pvec[i] = (char) (arc4random() % 256);
 109 #endif
 110 }
 111
 112
 113 /* get_des_char: return next char in an encrypted file */
 114 int
 115 get_des_char(FILE *fp)
 116 {
 117 #ifdef DES
 118         if (des_n >= des_ct) {
 119                 des_n = 0;
 120                 des_ct = cbc_decode(des_buf, fp);
 121         }
 122         return (des_ct > 0) ? des_buf[des_n++] : EOF;
 123 #else
 124         return (getc(fp));
 125 #endif
 126 }
 127
 128
 129 /* put_des_char: write a char to an encrypted file; return char written */
 130 int
 131 put_des_char(int c, FILE *fp)
 132 {
 133 #ifdef DES
 134         if (des_n == sizeof des_buf) {
 135                 des_ct = cbc_encode(des_buf, des_n, fp);
 136                 des_n = 0;
 137         }
 138         return (des_ct >= 0) ? (des_buf[des_n++] = c) : EOF;
 139 #else
 140         return (fputc(c, fp));
 141 #endif
 142 }
 143
 144
 145 /* flush_des_file: flush an encrypted file's output; return status */
 146 int
 147 flush_des_file(FILE *fp)
 148 {
 149 #ifdef DES
 150         if (des_n == sizeof des_buf) {
 151                 des_ct = cbc_encode(des_buf, des_n, fp);
 152                 des_n = 0;
 153         }
 154         return (des_ct >= 0 && cbc_encode(des_buf, des_n, fp) >= 0) ? 0 : EOF;
 155 #else
 156         return (fflush(fp));
 157 #endif
 158 }
 159
 160 #ifdef DES
 161 /*
 162  * get keyword from tty or stdin
 163  */
 164 int
 165 get_keyword(void)
 166 {
 167         char *p;                        /* used to obtain the key */
 168         DES_cblock msgbuf;              /* I/O buffer */
 169
 170         /*
 171          * get the key
 172          */
 173         if (*(p = getpass("Enter key: "))) {
 174
 175                 /*
 176                  * copy it, nul-padded, into the key area
 177                  */
 178                 expand_des_key(msgbuf, p);
 179                 MEMZERO(p, _PASSWORD_LEN);
 180                 set_des_key(&msgbuf);
 181                 MEMZERO(msgbuf, sizeof msgbuf);
 182                 return 1;
 183         }
 184         return 0;
 185 }
 186
 187
 188 /*
 189  * print a warning message and, possibly, terminate
 190  */
 191 void
 192 des_error(const char *s)
 193 {
 194         errmsg = s ? s : strerror(errno);
 195 }
 196
 197 /*
 198  * map a hex character to an integer
 199  */
 200 int
 201 hex_to_binary(int c, int radix)
 202 {
 203         switch(c) {
 204         case '0':               return(0x0);
 205         case '1':               return(0x1);
 206         case '2':               return(radix > 2 ? 0x2 : -1);
 207         case '3':               return(radix > 3 ? 0x3 : -1);
 208         case '4':               return(radix > 4 ? 0x4 : -1);
 209         case '5':               return(radix > 5 ? 0x5 : -1);
 210         case '6':               return(radix > 6 ? 0x6 : -1);
 211         case '7':               return(radix > 7 ? 0x7 : -1);
 212         case '8':               return(radix > 8 ? 0x8 : -1);
 213         case '9':               return(radix > 9 ? 0x9 : -1);
 214         case 'A': case 'a':     return(radix > 10 ? 0xa : -1);
 215         case 'B': case 'b':     return(radix > 11 ? 0xb : -1);
 216         case 'C': case 'c':     return(radix > 12 ? 0xc : -1);
 217         case 'D': case 'd':     return(radix > 13 ? 0xd : -1);
 218         case 'E': case 'e':     return(radix > 14 ? 0xe : -1);
 219         case 'F': case 'f':     return(radix > 15 ? 0xf : -1);
 220         }
 221         /*
 222          * invalid character
 223          */
 224         return(-1);
 225 }
 226
 227 /*
 228  * convert the key to a bit pattern
 229  *      obuf            bit pattern
 230  *      kbuf            the key itself
 231  */
 232 void
 233 expand_des_key(char *obuf, char *kbuf)
 234 {
 235         int i, j;                       /* counter in a for loop */
 236         int nbuf[64];                   /* used for hex/key translation */
 237
 238         /*
 239          * leading '0x' or '0X' == hex key
 240          */
 241         if (kbuf[0] == '0' && (kbuf[1] == 'x' || kbuf[1] == 'X')) {
 242                 kbuf = &kbuf[2];
 243                 /*
 244                  * now translate it, bombing on any illegal hex digit
 245                  */
 246                 for (i = 0; kbuf[i] && i < 16; i++)
 247                         if ((nbuf[i] = hex_to_binary((int) kbuf[i], 16)) == -1)
 248                                 des_error("bad hex digit in key");
 249                 while (i < 16)
 250                         nbuf[i++] = 0;
 251                 for (i = 0; i < 8; i++)
 252                         obuf[i] =
 253                             ((nbuf[2*i]&0xf)<<4) | (nbuf[2*i+1]&0xf);
 254                 /* preserve parity bits */
 255                 pflag = 1;
 256                 return;
 257         }
 258         /*
 259          * leading '0b' or '0B' == binary key
 260          */
 261         if (kbuf[0] == '0' && (kbuf[1] == 'b' || kbuf[1] == 'B')) {
 262                 kbuf = &kbuf[2];
 263                 /*
 264                  * now translate it, bombing on any illegal binary digit
 265                  */
 266                 for (i = 0; kbuf[i] && i < 16; i++)
 267                         if ((nbuf[i] = hex_to_binary((int) kbuf[i], 2)) == -1)
 268                                 des_error("bad binary digit in key");
 269                 while (i < 64)
 270                         nbuf[i++] = 0;
 271                 for (i = 0; i < 8; i++)
 272                         for (j = 0; j < 8; j++)
 273                                 obuf[i] = (obuf[i]<<1)|nbuf[8*i+j];
 274                 /* preserve parity bits */
 275                 pflag = 1;
 276                 return;
 277         }
 278         /*
 279          * no special leader -- ASCII
 280          */
 281         (void)strncpy(obuf, kbuf, 8);
 282 }
 283
 284 /*****************
 285  * DES FUNCTIONS *
 286  *****************/
 287 /*
 288  * This sets the DES key and (if you're using the deszip version)
 289  * the direction of the transformation.  This uses the Sun
 290  * to map the 64-bit key onto the 56 bits that the key schedule
 291  * generation routines use: the old way, which just uses the user-
 292  * supplied 64 bits as is, and the new way, which resets the parity
 293  * bit to be the same as the low-order bit in each character.  The
 294  * new way generates a greater variety of key schedules, since many
 295  * systems set the parity (high) bit of each character to 0, and the
 296  * DES ignores the low order bit of each character.
 297  */
 298 void
 299 set_des_key(DES_cblock *buf)                    /* key block */
 300 {
 301         int i, j;                               /* counter in a for loop */
 302         int par;                                /* parity counter */
 303
 304         /*
 305          * if the parity is not preserved, flip it
 306          */
 307         if (!pflag) {
 308                 for (i = 0; i < 8; i++) {
 309                         par = 0;
 310                         for (j = 1; j < 8; j++)
 311                                 if ((bits[j] & (*buf)[i]) != 0)
 312                                         par++;
 313                         if ((par & 0x01) == 0x01)
 314                                 (*buf)[i] &= 0x7f;
 315                         else
 316                                 (*buf)[i] = ((*buf)[i] & 0x7f) | 0x80;
 317                 }
 318         }
 319
 320         DES_set_odd_parity(buf);
 321         DES_set_key(buf, &schedule);
 322 }
 323
 324
 325 /*
 326  * This encrypts using the Cipher Block Chaining mode of DES
 327  */
 328 int
 329 cbc_encode(unsigned char *msgbuf, int n, FILE *fp)
 330 {
 331         int inverse = 0;        /* 0 to encrypt, 1 to decrypt */
 332
 333         /*
 334          * do the transformation
 335          */
 336         if (n == 8) {
 337                 for (n = 0; n < 8; n++)
 338                         msgbuf[n] ^= ivec[n];
 339                 DES_XFORM((DES_cblock *)msgbuf);
 340                 MEMCPY(ivec, msgbuf, 8);
 341                 return WRITE(msgbuf, 8, fp);
 342         }
 343         /*
 344          * at EOF or last block -- in either case, the last byte contains
 345          * the character representation of the number of bytes in it
 346          */
 347 /*
 348         MEMZERO(msgbuf +  n, 8 - n);
 349 */
 350         /*
 351          *  Pad the last block randomly
 352          */
 353         (void)MEMCPY(msgbuf + n, pvec, 8 - n);
 354         msgbuf[7] = n;
 355         for (n = 0; n < 8; n++)
 356                 msgbuf[n] ^= ivec[n];
 357         DES_XFORM((DES_cblock *)msgbuf);
 358         return WRITE(msgbuf, 8, fp);
 359 }
 360
 361 /*
 362  * This decrypts using the Cipher Block Chaining mode of DES
 363  *      msgbuf  I/O buffer
 364  *      fp      input file descriptor
 365  */
 366 int
 367 cbc_decode(unsigned char *msgbuf, FILE *fp)
 368 {
 369         DES_cblock tbuf;        /* temp buffer for initialization vector */
 370         int n;                  /* number of bytes actually read */
 371         int c;                  /* used to test for EOF */
 372         int inverse = 1;        /* 0 to encrypt, 1 to decrypt */
 373
 374         if ((n = READ(msgbuf, 8, fp)) == 8) {
 375                 /*
 376                  * do the transformation
 377                  */
 378                 MEMCPY(tbuf, msgbuf, 8);
 379                 DES_XFORM((DES_cblock *)msgbuf);
 380                 for (c = 0; c < 8; c++)
 381                         msgbuf[c] ^= ivec[c];
 382                 MEMCPY(ivec, tbuf, 8);
 383                 /*
 384                  * if the last one, handle it specially
 385                  */
 386                 if ((c = fgetc(fp)) == EOF) {
 387                         n = msgbuf[7];
 388                         if (n < 0 || n > 7) {
 389                                 des_error("decryption failed (block corrupted)");
 390                                 return EOF;
 391                         }
 392                 } else
 393                         (void)ungetc(c, fp);
 394                 return n;
 395         }
 396         if (n > 0)
 397                 des_error("decryption failed (incomplete block)");
 398         else if (n < 0)
 399                 des_error("cannot read file");
 400         return EOF;
 401 }
 402 #endif  /* DES */