bin/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  * 3. 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  *      from: @(#)bdes.c        5.5 (Berkeley) 6/27/91
  34  *
  35  * @(#)cbc.c,v 1.2 1994/02/01 00:34:36 alm Exp
  36  * $FreeBSD: head/bin/ed/cbc.c 300340 2016-05-21 00:45:42Z pfg $
  37  */
  38
  39 #include <sys/types.h>
  40 #include <errno.h>
  41 #include <pwd.h>
  42 #ifdef DES
  43 #include <time.h>
  44 #include <openssl/des.h>
  45 #define ED_DES_INCLUDES
  46 #endif
  47
  48 #include "ed.h"
  49
  50
  51 /*
  52  * BSD and System V systems offer special library calls that do
  53  * block move_liness and fills, so if possible we take advantage of them
  54  */
  55 #define MEMCPY(dest,src,len)    memcpy((dest),(src),(len))
  56 #define MEMZERO(dest,len)       memset((dest), 0, (len))
  57
  58 /* Hide the calls to the primitive encryption routines. */
  59 #define DES_XFORM(buf)                                                  \
  60                 DES_ecb_encrypt(buf, buf, &schedule,                    \
  61                     inverse ? DES_DECRYPT : DES_ENCRYPT);
  62
  63 /*
  64  * read/write - no error checking
  65  */
  66 #define READ(buf, n, fp)        fread(buf, sizeof(char), n, fp)
  67 #define WRITE(buf, n, fp)       fwrite(buf, sizeof(char), n, fp)
  68
  69 /*
  70  * global variables and related macros
  71  */
  72
  73 #ifdef DES
  74 static DES_cblock ivec;                 /* initialization vector */
  75 static DES_cblock pvec;                 /* padding vector */
  76
  77 static char bits[] = {                  /* used to extract bits from a char */
  78         '\200', '\100', '\040', '\020', '\010', '\004', '\002', '\001'
  79 };
  80
  81 static int pflag;                       /* 1 to preserve parity bits */
  82
  83 static DES_key_schedule schedule;       /* expanded DES key */
  84
  85 static unsigned char des_buf[8];/* shared buffer for get_des_char/put_des_char */
  86 static int des_ct = 0;          /* count for get_des_char/put_des_char */
  87 static int des_n = 0;           /* index for put_des_char/get_des_char */
  88 #endif
  89
  90 /* init_des_cipher: initialize DES */
  91 void
  92 init_des_cipher(void)
  93 {
  94 #ifdef DES
  95         des_ct = des_n = 0;
  96
  97         /* initialize the initialization vector */
  98         MEMZERO(ivec, 8);
  99
 100         /* initialize the padding vector */
 101         arc4random_buf(pvec, sizeof(pvec));
 102 #endif
 103 }
 104
 105
 106 /* get_des_char: return next char in an encrypted file */
 107 int
 108 get_des_char(FILE *fp)
 109 {
 110 #ifdef DES
 111         if (des_n >= des_ct) {
 112                 des_n = 0;
 113                 des_ct = cbc_decode(des_buf, fp);
 114         }
 115         return (des_ct > 0) ? des_buf[des_n++] : EOF;
 116 #else
 117         return (getc(fp));
 118 #endif
 119 }
 120
 121
 122 /* put_des_char: write a char to an encrypted file; return char written */
 123 int
 124 put_des_char(int c, FILE *fp)
 125 {
 126 #ifdef DES
 127         if (des_n == sizeof des_buf) {
 128                 des_ct = cbc_encode(des_buf, des_n, fp);
 129                 des_n = 0;
 130         }
 131         return (des_ct >= 0) ? (des_buf[des_n++] = c) : EOF;
 132 #else
 133         return (fputc(c, fp));
 134 #endif
 135 }
 136
 137
 138 /* flush_des_file: flush an encrypted file's output; return status */
 139 int
 140 flush_des_file(FILE *fp)
 141 {
 142 #ifdef DES
 143         if (des_n == sizeof des_buf) {
 144                 des_ct = cbc_encode(des_buf, des_n, fp);
 145                 des_n = 0;
 146         }
 147         return (des_ct >= 0 && cbc_encode(des_buf, des_n, fp) >= 0) ? 0 : EOF;
 148 #else
 149         return (fflush(fp));
 150 #endif
 151 }
 152
 153 #ifdef DES
 154 /*
 155  * get keyword from tty or stdin
 156  */
 157 int
 158 get_keyword(void)
 159 {
 160         char *p;                        /* used to obtain the key */
 161         DES_cblock msgbuf;              /* I/O buffer */
 162
 163         /*
 164          * get the key
 165          */
 166         if ((p = getpass("Enter key: ")) != NULL && *p != '\0') {
 167
 168                 /*
 169                  * copy it, nul-padded, into the key area
 170                  */
 171                 expand_des_key(msgbuf, p);
 172                 MEMZERO(p, _PASSWORD_LEN);
 173                 set_des_key(&msgbuf);
 174                 MEMZERO(msgbuf, sizeof msgbuf);
 175                 return 1;
 176         }
 177         return 0;
 178 }
 179
 180
 181 /*
 182  * print a warning message and, possibly, terminate
 183  */
 184 void
 185 des_error(const char *s)
 186 {
 187         errmsg = s ? s : strerror(errno);
 188 }
 189
 190 /*
 191  * map a hex character to an integer
 192  */
 193 int
 194 hex_to_binary(int c, int radix)
 195 {
 196         switch(c) {
 197         case '0':               return(0x0);
 198         case '1':               return(0x1);
 199         case '2':               return(radix > 2 ? 0x2 : -1);
 200         case '3':               return(radix > 3 ? 0x3 : -1);
 201         case '4':               return(radix > 4 ? 0x4 : -1);
 202         case '5':               return(radix > 5 ? 0x5 : -1);
 203         case '6':               return(radix > 6 ? 0x6 : -1);
 204         case '7':               return(radix > 7 ? 0x7 : -1);
 205         case '8':               return(radix > 8 ? 0x8 : -1);
 206         case '9':               return(radix > 9 ? 0x9 : -1);
 207         case 'A': case 'a':     return(radix > 10 ? 0xa : -1);
 208         case 'B': case 'b':     return(radix > 11 ? 0xb : -1);
 209         case 'C': case 'c':     return(radix > 12 ? 0xc : -1);
 210         case 'D': case 'd':     return(radix > 13 ? 0xd : -1);
 211         case 'E': case 'e':     return(radix > 14 ? 0xe : -1);
 212         case 'F': case 'f':     return(radix > 15 ? 0xf : -1);
 213         }
 214         /*
 215          * invalid character
 216          */
 217         return(-1);
 218 }
 219
 220 /*
 221  * convert the key to a bit pattern
 222  *      obuf            bit pattern
 223  *      kbuf            the key itself
 224  */
 225 void
 226 expand_des_key(char *obuf, char *kbuf)
 227 {
 228         int i, j;                       /* counter in a for loop */
 229         int nbuf[64];                   /* used for hex/key translation */
 230
 231         /*
 232          * leading '0x' or '0X' == hex key
 233          */
 234         if (kbuf[0] == '0' && (kbuf[1] == 'x' || kbuf[1] == 'X')) {
 235                 kbuf = &kbuf[2];
 236                 /*
 237                  * now translate it, bombing on any illegal hex digit
 238                  */
 239                 for (i = 0; i < 16 && kbuf[i]; i++)
 240                         if ((nbuf[i] = hex_to_binary((int) kbuf[i], 16)) == -1)
 241                                 des_error("bad hex digit in key");
 242                 while (i < 16)
 243                         nbuf[i++] = 0;
 244                 for (i = 0; i < 8; i++)
 245                         obuf[i] =
 246                             ((nbuf[2*i]&0xf)<<4) | (nbuf[2*i+1]&0xf);
 247                 /* preserve parity bits */
 248                 pflag = 1;
 249                 return;
 250         }
 251         /*
 252          * leading '0b' or '0B' == binary key
 253          */
 254         if (kbuf[0] == '0' && (kbuf[1] == 'b' || kbuf[1] == 'B')) {
 255                 kbuf = &kbuf[2];
 256                 /*
 257                  * now translate it, bombing on any illegal binary digit
 258                  */
 259                 for (i = 0; i < 16 && kbuf[i]; i++)
 260                         if ((nbuf[i] = hex_to_binary((int) kbuf[i], 2)) == -1)
 261                                 des_error("bad binary digit in key");
 262                 while (i < 64)
 263                         nbuf[i++] = 0;
 264                 for (i = 0; i < 8; i++)
 265                         for (j = 0; j < 8; j++)
 266                                 obuf[i] = (obuf[i]<<1)|nbuf[8*i+j];
 267                 /* preserve parity bits */
 268                 pflag = 1;
 269                 return;
 270         }
 271         /*
 272          * no special leader -- ASCII
 273          */
 274         strncpy(obuf, kbuf, 8);
 275 }
 276
 277 /*****************
 278  * DES FUNCTIONS *
 279  *****************/
 280 /*
 281  * This sets the DES key and (if you're using the deszip version)
 282  * the direction of the transformation.  This uses the Sun
 283  * to map the 64-bit key onto the 56 bits that the key schedule
 284  * generation routines use: the old way, which just uses the user-
 285  * supplied 64 bits as is, and the new way, which resets the parity
 286  * bit to be the same as the low-order bit in each character.  The
 287  * new way generates a greater variety of key schedules, since many
 288  * systems set the parity (high) bit of each character to 0, and the
 289  * DES ignores the low order bit of each character.
 290  */
 291 void
 292 set_des_key(DES_cblock *buf)                    /* key block */
 293 {
 294         int i, j;                               /* counter in a for loop */
 295         int par;                                /* parity counter */
 296
 297         /*
 298          * if the parity is not preserved, flip it
 299          */
 300         if (!pflag) {
 301                 for (i = 0; i < 8; i++) {
 302                         par = 0;
 303                         for (j = 1; j < 8; j++)
 304                                 if ((bits[j] & (*buf)[i]) != 0)
 305                                         par++;
 306                         if ((par & 0x01) == 0x01)
 307                                 (*buf)[i] &= 0x7f;
 308                         else
 309                                 (*buf)[i] = ((*buf)[i] & 0x7f) | 0x80;
 310                 }
 311         }
 312
 313         DES_set_odd_parity(buf);
 314         DES_set_key(buf, &schedule);
 315 }
 316
 317
 318 /*
 319  * This encrypts using the Cipher Block Chaining mode of DES
 320  */
 321 int
 322 cbc_encode(unsigned char *msgbuf, int n, FILE *fp)
 323 {
 324         int inverse = 0;        /* 0 to encrypt, 1 to decrypt */
 325
 326         /*
 327          * do the transformation
 328          */
 329         if (n == 8) {
 330                 for (n = 0; n < 8; n++)
 331                         msgbuf[n] ^= ivec[n];
 332                 DES_XFORM((DES_cblock *)msgbuf);
 333                 MEMCPY(ivec, msgbuf, 8);
 334                 return WRITE(msgbuf, 8, fp);
 335         }
 336         /*
 337          * at EOF or last block -- in either case, the last byte contains
 338          * the character representation of the number of bytes in it
 339          */
 340 /*
 341         MEMZERO(msgbuf +  n, 8 - n);
 342 */
 343         /*
 344          *  Pad the last block randomly
 345          */
 346         MEMCPY(msgbuf + n, pvec, 8 - n);
 347         msgbuf[7] = n;
 348         for (n = 0; n < 8; n++)
 349                 msgbuf[n] ^= ivec[n];
 350         DES_XFORM((DES_cblock *)msgbuf);
 351         return WRITE(msgbuf, 8, fp);
 352 }
 353
 354 /*
 355  * This decrypts using the Cipher Block Chaining mode of DES
 356  *      msgbuf  I/O buffer
 357  *      fp      input file descriptor
 358  */
 359 int
 360 cbc_decode(unsigned char *msgbuf, FILE *fp)
 361 {
 362         DES_cblock tbuf;        /* temp buffer for initialization vector */
 363         int n;                  /* number of bytes actually read */
 364         int c;                  /* used to test for EOF */
 365         int inverse = 1;        /* 0 to encrypt, 1 to decrypt */
 366
 367         if ((n = READ(msgbuf, 8, fp)) == 8) {
 368                 /*
 369                  * do the transformation
 370                  */
 371                 MEMCPY(tbuf, msgbuf, 8);
 372                 DES_XFORM((DES_cblock *)msgbuf);
 373                 for (c = 0; c < 8; c++)
 374                         msgbuf[c] ^= ivec[c];
 375                 MEMCPY(ivec, tbuf, 8);
 376                 /*
 377                  * if the last one, handle it specially
 378                  */
 379                 if ((c = fgetc(fp)) == EOF) {
 380                         n = msgbuf[7];
 381                         if (n < 0 || n > 7) {
 382                                 des_error("decryption failed (block corrupted)");
 383                                 return EOF;
 384                         }
 385                 } else
 386                         ungetc(c, fp);
 387                 return n;
 388         }
 389         if (n > 0)
 390                 des_error("decryption failed (incomplete block)");
 391         else if (n < 0)
 392                 des_error("cannot read file");
 393         return EOF;
 394 }
 395 #endif  /* DES */