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. All advertising materials mentioning features or use of this software
  18  *    must display the following acknowledgement:
  19  *      This product includes software developed by the University of
  20  *      California, Berkeley and its contributors.
  21  * 4. Neither the name of the University nor the names of its contributors
  22  *    may be used to endorse or promote products derived from this software
  23  *    without specific prior written permission.
  24  *
  25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  35  * SUCH DAMAGE.
  36  *
  37  *      from: @(#)bdes.c        5.5 (Berkeley) 6/27/91
  38  *
  39  * @(#)cbc.c,v 1.2 1994/02/01 00:34:36 alm Exp
  40  * $FreeBSD: src/bin/ed/cbc.c,v 1.12.2.1 2001/07/04 22:32:18 kris Exp $
  41  * $DragonFly: src/bin/ed/cbc.c,v 1.8 2005/02/02 18:46:01 joerg Exp $
  42  */
  43
  44 #include <sys/types.h>
  45 #include <errno.h>
  46 #include <pwd.h>
  47 #ifdef DES
  48 #include <time.h>
  49 #endif
  50
  51 #include "ed.h"
  52
  53
  54 /*
  55  * BSD and System V systems offer special library calls that do
  56  * block move_liness and fills, so if possible we take advantage of them
  57  */
  58 #define MEMCPY(dest,src,len)    memcpy((dest),(src),(len))
  59 #define MEMZERO(dest,len)       memset((dest), 0, (len))
  60
  61 /* Hide the calls to the primitive encryption routines. */
  62 #define DES_KEY(buf) \
  63         if (des_setkey(buf)) \
  64                 des_error("des_setkey");
  65 #define DES_XFORM(buf) \
  66         if (des_cipher(buf, buf, 0L, (inverse ? -1 : 1))) \
  67                 des_error("des_cipher");
  68
  69 /*
  70  * read/write - no error checking
  71  */
  72 #define READ(buf, n, fp)        fread(buf, sizeof(char), n, fp)
  73 #define WRITE(buf, n, fp)       fwrite(buf, sizeof(char), n, fp)
  74
  75 /*
  76  * some things to make references easier
  77  */
  78 typedef char Desbuf[8];
  79 #define CHAR(x,i)       (x[i])
  80 #define UCHAR(x,i)      (x[i])
  81 #define BUFFER(x)       (x)
  82 #define UBUFFER(x)      (x)
  83
  84 /*
  85  * global variables and related macros
  86  */
  87
  88 enum {                                  /* encrypt, decrypt, authenticate */
  89         MODE_ENCRYPT, MODE_DECRYPT, MODE_AUTHENTICATE
  90 } mode = MODE_ENCRYPT;
  91
  92 Desbuf ivec;                            /* initialization vector */
  93 Desbuf pvec;                            /* padding vector */
  94 char bits[] = {                         /* used to extract bits from a char */
  95         '\200', '\100', '\040', '\020', '\010', '\004', '\002', '\001'
  96 };
  97 int pflag;                              /* 1 to preserve parity bits */
  98
  99 char des_buf[8];                /* shared buffer for get_des_char/put_des_char */
 100 int des_ct = 0;                 /* count for get_des_char/put_des_char */
 101 int des_n = 0;                  /* index for put_des_char/get_des_char */
 102
 103
 104 /* init_des_cipher: initialize DES */
 105 void
 106 init_des_cipher(void)
 107 {
 108 #ifdef DES
 109         int i;
 110
 111         des_ct = des_n = 0;
 112
 113         /* initialize the initialization vector */
 114         MEMZERO(ivec, 8);
 115
 116         /* initialize the padding vector */
 117         for (i = 0; i < 8; i++)
 118                 CHAR(pvec, i) = (char) (arc4random() % 256);
 119 #endif
 120 }
 121
 122
 123 /* get_des_char: return next char in an encrypted file */
 124 int
 125 get_des_char(FILE *fp)
 126 {
 127 #ifdef DES
 128         if (des_n >= des_ct) {
 129                 des_n = 0;
 130                 des_ct = cbc_decode(des_buf, fp);
 131         }
 132         return (des_ct > 0) ? (unsigned char)des_buf[des_n++] : EOF;
 133 #else
 134         return (getc(fp));
 135 #endif
 136 }
 137
 138
 139 /* put_des_char: write a char to an encrypted file; return char written */
 140 int
 141 put_des_char(int c, FILE *fp)
 142 {
 143 #ifdef DES
 144         if (des_n == sizeof des_buf) {
 145                 des_ct = cbc_encode(des_buf, des_n, fp);
 146                 des_n = 0;
 147         }
 148         return (des_ct >= 0) ? (des_buf[des_n++] = (char)c) : EOF;
 149 #else
 150         return (fputc(c, fp));
 151 #endif
 152 }
 153
 154
 155 /* flush_des_file: flush an encrypted file's output; return status */
 156 int
 157 flush_des_file(FILE *fp)
 158 {
 159 #ifdef DES
 160         if (des_n == sizeof des_buf) {
 161                 des_ct = cbc_encode(des_buf, des_n, fp);
 162                 des_n = 0;
 163         }
 164         return (des_ct >= 0 && cbc_encode(des_buf, des_n, fp) >= 0) ? 0 : EOF;
 165 #else
 166         return (fflush(fp));
 167 #endif
 168 }
 169
 170 #ifdef DES
 171 /*
 172  * get keyword from tty or stdin
 173  */
 174 int
 175 get_keyword(void)
 176 {
 177         char *p;                /* used to obtain the key */
 178         Desbuf msgbuf;                  /* I/O buffer */
 179
 180         /*
 181          * get the key
 182          */
 183         if (*(p = getpass("Enter key: "))) {
 184
 185                 /*
 186                  * copy it, nul-padded, into the key area
 187                  */
 188                 expand_des_key(BUFFER(msgbuf), p);
 189                 MEMZERO(p, _PASSWORD_LEN);
 190                 set_des_key(msgbuf);
 191                 MEMZERO(msgbuf, sizeof msgbuf);
 192                 return 1;
 193         }
 194         return 0;
 195 }
 196
 197
 198 /*
 199  * print a warning message and, possibly, terminate
 200  */
 201 void
 202 des_error(const char *s)
 203 {
 204         sprintf(errmsg, "%s", s ? s : strerror(errno));
 205 }
 206
 207 /*
 208  * map a hex character to an integer
 209  */
 210 int
 211 hex_to_binary(int c, int radix)
 212 {
 213         switch(c) {
 214         case '0':               return(0x0);
 215         case '1':               return(0x1);
 216         case '2':               return(radix > 2 ? 0x2 : -1);
 217         case '3':               return(radix > 3 ? 0x3 : -1);
 218         case '4':               return(radix > 4 ? 0x4 : -1);
 219         case '5':               return(radix > 5 ? 0x5 : -1);
 220         case '6':               return(radix > 6 ? 0x6 : -1);
 221         case '7':               return(radix > 7 ? 0x7 : -1);
 222         case '8':               return(radix > 8 ? 0x8 : -1);
 223         case '9':               return(radix > 9 ? 0x9 : -1);
 224         case 'A': case 'a':     return(radix > 10 ? 0xa : -1);
 225         case 'B': case 'b':     return(radix > 11 ? 0xb : -1);
 226         case 'C': case 'c':     return(radix > 12 ? 0xc : -1);
 227         case 'D': case 'd':     return(radix > 13 ? 0xd : -1);
 228         case 'E': case 'e':     return(radix > 14 ? 0xe : -1);
 229         case 'F': case 'f':     return(radix > 15 ? 0xf : -1);
 230         }
 231         /*
 232          * invalid character
 233          */
 234         return(-1);
 235 }
 236
 237 /*
 238  * convert the key to a bit pattern
 239  */
 240 void
 241 expand_des_key(char *obuf, char *inbuf)
 242 {
 243         int i, j;               /* counter in a for loop */
 244         int nbuf[64];                   /* used for hex/key translation */
 245
 246         /*
 247          * leading '0x' or '0X' == hex key
 248          */
 249         if (inbuf[0] == '0' && (inbuf[1] == 'x' || inbuf[1] == 'X')) {
 250                 inbuf = &inbuf[2];
 251                 /*
 252                  * now translate it, bombing on any illegal hex digit
 253                  */
 254                 for (i = 0; inbuf[i] && i < 16; i++)
 255                         if ((nbuf[i] = hex_to_binary((int) inbuf[i], 16)) == -1)
 256                                 des_error("bad hex digit in key");
 257                 while (i < 16)
 258                         nbuf[i++] = 0;
 259                 for (i = 0; i < 8; i++)
 260                         obuf[i] =
 261                             ((nbuf[2*i]&0xf)<<4) | (nbuf[2*i+1]&0xf);
 262                 /* preserve parity bits */
 263                 pflag = 1;
 264                 return;
 265         }
 266         /*
 267          * leading '0b' or '0B' == binary key
 268          */
 269         if (inbuf[0] == '0' && (inbuf[1] == 'b' || inbuf[1] == 'B')) {
 270                 inbuf = &inbuf[2];
 271                 /*
 272                  * now translate it, bombing on any illegal binary digit
 273                  */
 274                 for (i = 0; inbuf[i] && i < 16; i++)
 275                         if ((nbuf[i] = hex_to_binary((int) inbuf[i], 2)) == -1)
 276                                 des_error("bad binary digit in key");
 277                 while (i < 64)
 278                         nbuf[i++] = 0;
 279                 for (i = 0; i < 8; i++)
 280                         for (j = 0; j < 8; j++)
 281                                 obuf[i] = (obuf[i]<<1)|nbuf[8*i+j];
 282                 /* preserve parity bits */
 283                 pflag = 1;
 284                 return;
 285         }
 286         /*
 287          * no special leader -- ASCII
 288          */
 289         strncpy(obuf, inbuf, 8);
 290 }
 291
 292 /*****************
 293  * DES FUNCTIONS *
 294  *****************/
 295 /*
 296  * This sets the DES key and (if you're using the deszip version)
 297  * the direction of the transformation.  This uses the Sun
 298  * to map the 64-bit key onto the 56 bits that the key schedule
 299  * generation routines use: the old way, which just uses the user-
 300  * supplied 64 bits as is, and the new way, which resets the parity
 301  * bit to be the same as the low-order bit in each character.  The
 302  * new way generates a greater variety of key schedules, since many
 303  * systems set the parity (high) bit of each character to 0, and the
 304  * DES ignores the low order bit of each character.
 305  */
 306 void
 307 set_des_key(Desbuf buf)
 308 {
 309         int i, j;                       /* counter in a for loop */
 310         int par;                        /* parity counter */
 311
 312         /*
 313          * if the parity is not preserved, flip it
 314          */
 315         if (!pflag) {
 316                 for (i = 0; i < 8; i++) {
 317                         par = 0;
 318                         for (j = 1; j < 8; j++)
 319                                 if ((bits[j]&UCHAR(buf, i)) != 0)
 320                                         par++;
 321                         if ((par&01) == 01)
 322                                 UCHAR(buf, i) = UCHAR(buf, i)&0177;
 323                         else
 324                                 UCHAR(buf, i) = (UCHAR(buf, i)&0177)|0200;
 325                 }
 326         }
 327
 328         DES_KEY(UBUFFER(buf));
 329 }
 330
 331
 332 /*
 333  * This encrypts using the Cipher Block Chaining mode of DES
 334  */
 335 int
 336 cbc_encode(char *msgbuf, int n, FILE *fp)
 337 {
 338         int inverse = 0;        /* 0 to encrypt, 1 to decrypt */
 339
 340         /*
 341          * do the transformation
 342          */
 343         if (n == 8) {
 344                 for (n = 0; n < 8; n++)
 345                         CHAR(msgbuf, n) ^= CHAR(ivec, n);
 346                 DES_XFORM(UBUFFER(msgbuf));
 347                 MEMCPY(BUFFER(ivec), BUFFER(msgbuf), 8);
 348                 return WRITE(BUFFER(msgbuf), 8, fp);
 349         }
 350         /*
 351          * at EOF or last block -- in either case, the last byte contains
 352          * the character representation of the number of bytes in it
 353          */
 354 /*
 355         MEMZERO(msgbuf +  n, 8 - n);
 356 */
 357         /*
 358          *  Pad the last block randomly
 359          */
 360         MEMCPY(BUFFER(msgbuf + n), BUFFER(pvec), 8 - n);
 361         CHAR(msgbuf, 7) = n;
 362         for (n = 0; n < 8; n++)
 363                 CHAR(msgbuf, n) ^= CHAR(ivec, n);
 364         DES_XFORM(UBUFFER(msgbuf));
 365         return WRITE(BUFFER(msgbuf), 8, fp);
 366 }
 367
 368 /*
 369  * This decrypts using the Cipher Block Chaining mode of DES
 370  */
 371 int
 372 cbc_decode(char *msgbuf, FILE *fp)
 373 {
 374         Desbuf inbuf;   /* temp buffer for initialization vector */
 375         int n;          /* number of bytes actually read */
 376         int c;          /* used to test for EOF */
 377         int inverse = 1;        /* 0 to encrypt, 1 to decrypt */
 378
 379         if ((n = READ(BUFFER(msgbuf), 8, fp)) == 8) {
 380                 /*
 381                  * do the transformation
 382                  */
 383                 MEMCPY(BUFFER(inbuf), BUFFER(msgbuf), 8);
 384                 DES_XFORM(UBUFFER(msgbuf));
 385                 for (c = 0; c < 8; c++)
 386                         UCHAR(msgbuf, c) ^= UCHAR(ivec, c);
 387                 MEMCPY(BUFFER(ivec), BUFFER(inbuf), 8);
 388                 /*
 389                  * if the last one, handle it specially
 390                  */
 391                 if ((c = fgetc(fp)) == EOF) {
 392                         n = CHAR(msgbuf, 7);
 393                         if (n < 0 || n > 7) {
 394                                 des_error("decryption failed (block corrupted)");
 395                                 return EOF;
 396                         }
 397                 } else
 398                         ungetc(c, fp);
 399                 return n;
 400         }
 401         if (n > 0)
 402                 des_error("decryption failed (incomplete block)");
 403         else if (n < 0)
 404                 des_error("cannot read file");
 405         return EOF;
 406 }
 407 #endif  /* DES */