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 1.20 2004/04/06 20:06:47 markm Exp $
  41  * $DragonFly: src/bin/ed/cbc.c,v 1.10 2007/04/06 23:36:54 pavalos Exp $
  42  */
  43
  44 #include <sys/types.h>
  45 #include <errno.h>
  46 #include <pwd.h>
  47 #ifdef DES
  48 #include <time.h>
  49 #include <openssl/des.h>
  50 #define ED_DES_INCLUDES
  51 #endif
  52
  53 #include "ed.h"
  54
  55
  56 /*
  57  * BSD and System V systems offer special library calls that do
  58  * block move_liness and fills, so if possible we take advantage of them
  59  */
  60 #define MEMCPY(dest,src,len)    memcpy((dest),(src),(len))
  61 #define MEMZERO(dest,len)       memset((dest), 0, (len))
  62
  63 /* Hide the calls to the primitive encryption routines. */
  64 #define DES_XFORM(buf) \
  65                 DES_ecb_encrypt(buf, buf, &schedule,    \
  66                     inverse ? DES_DECRYPT : DES_ENCRYPT);
  67 /*
  68  * read/write - no error checking
  69  */
  70 #define READ(buf, n, fp)        fread(buf, sizeof(char), n, fp)
  71 #define WRITE(buf, n, fp)       fwrite(buf, sizeof(char), n, fp)
  72
  73 /*
  74  * global variables and related macros
  75  */
  76
  77 enum {                                  /* encrypt, decrypt, authenticate */
  78         MODE_ENCRYPT, MODE_DECRYPT, MODE_AUTHENTICATE
  79 } mode = MODE_ENCRYPT;
  80
  81 #ifdef DES
  82 DES_cblock ivec;                                /* initialization vector */
  83 DES_cblock pvec;                                /* padding vector */
  84 #endif
  85
  86 char bits[] = {                         /* used to extract bits from a char */
  87         '\200', '\100', '\040', '\020', '\010', '\004', '\002', '\001'
  88 };
  89
  90 int pflag;                              /* 1 to preserve parity bits */
  91
  92 #ifdef DES
  93 DES_key_schedule schedule;              /* expanded DES key */
  94 #endif
  95
  96 char des_buf[8];                /* shared buffer for get_des_char/put_des_char */
  97 int des_ct = 0;                 /* count for get_des_char/put_des_char */
  98 int des_n = 0;                  /* index for put_des_char/get_des_char */
  99
 100
 101 /* init_des_cipher: initialize DES */
 102 void
 103 init_des_cipher(void)
 104 {
 105 #ifdef DES
 106         int i;
 107
 108         des_ct = des_n = 0;
 109
 110         /* initialize the initialization vector */
 111         MEMZERO(ivec, 8);
 112
 113         /* initialize the padding vector */
 114         for (i = 0; i < 8; i++)
 115                 pvec[i] = (char) (arc4random() % 256);
 116 #endif
 117 }
 118
 119
 120 /* get_des_char: return next char in an encrypted file */
 121 int
 122 get_des_char(FILE *fp)
 123 {
 124 #ifdef DES
 125         if (des_n >= des_ct) {
 126                 des_n = 0;
 127                 des_ct = cbc_decode(des_buf, fp);
 128         }
 129         return (des_ct > 0) ? (unsigned char)des_buf[des_n++] : EOF;
 130 #else
 131         return (getc(fp));
 132 #endif
 133 }
 134
 135
 136 /* put_des_char: write a char to an encrypted file; return char written */
 137 int
 138 put_des_char(int c, FILE *fp)
 139 {
 140 #ifdef DES
 141         if (des_n == sizeof des_buf) {
 142                 des_ct = cbc_encode(des_buf, des_n, fp);
 143                 des_n = 0;
 144         }
 145         return (des_ct >= 0) ? (des_buf[des_n++] = (char)c) : EOF;
 146 #else
 147         return (fputc(c, fp));
 148 #endif
 149 }
 150
 151
 152 /* flush_des_file: flush an encrypted file's output; return status */
 153 int
 154 flush_des_file(FILE *fp)
 155 {
 156 #ifdef DES
 157         if (des_n == sizeof des_buf) {
 158                 des_ct = cbc_encode(des_buf, des_n, fp);
 159                 des_n = 0;
 160         }
 161         return (des_ct >= 0 && cbc_encode(des_buf, des_n, fp) >= 0) ? 0 : EOF;
 162 #else
 163         return (fflush(fp));
 164 #endif
 165 }
 166
 167 #ifdef DES
 168 /*
 169  * get keyword from tty or stdin
 170  */
 171 int
 172 get_keyword(void)
 173 {
 174         char *p;                /* used to obtain the key */
 175         DES_cblock msgbuf;      /* I/O buffer */
 176
 177         /*
 178          * get the key
 179          */
 180         if (*(p = getpass("Enter key: "))) {
 181
 182                 /*
 183                  * copy it, nul-padded, into the key area
 184                  */
 185                 expand_des_key(msgbuf, p);
 186                 MEMZERO(p, _PASSWORD_LEN);
 187                 set_des_key(&msgbuf);
 188                 MEMZERO(msgbuf, sizeof msgbuf);
 189                 return 1;
 190         }
 191         return 0;
 192 }
 193
 194
 195 /*
 196  * print a warning message and, possibly, terminate
 197  */
 198 void
 199 des_error(const char *s)
 200 {
 201         errmsg = s ? s : strerror(errno);
 202 }
 203
 204 /*
 205  * map a hex character to an integer
 206  */
 207 int
 208 hex_to_binary(int c, int radix)
 209 {
 210         switch(c) {
 211         case '0':               return(0x0);
 212         case '1':               return(0x1);
 213         case '2':               return(radix > 2 ? 0x2 : -1);
 214         case '3':               return(radix > 3 ? 0x3 : -1);
 215         case '4':               return(radix > 4 ? 0x4 : -1);
 216         case '5':               return(radix > 5 ? 0x5 : -1);
 217         case '6':               return(radix > 6 ? 0x6 : -1);
 218         case '7':               return(radix > 7 ? 0x7 : -1);
 219         case '8':               return(radix > 8 ? 0x8 : -1);
 220         case '9':               return(radix > 9 ? 0x9 : -1);
 221         case 'A': case 'a':     return(radix > 10 ? 0xa : -1);
 222         case 'B': case 'b':     return(radix > 11 ? 0xb : -1);
 223         case 'C': case 'c':     return(radix > 12 ? 0xc : -1);
 224         case 'D': case 'd':     return(radix > 13 ? 0xd : -1);
 225         case 'E': case 'e':     return(radix > 14 ? 0xe : -1);
 226         case 'F': case 'f':     return(radix > 15 ? 0xf : -1);
 227         }
 228         /*
 229          * invalid character
 230          */
 231         return(-1);
 232 }
 233
 234 /*
 235  * convert the key to a bit pattern
 236  *      obuf            bit pattern
 237  *      inbuf           the key itself
 238  */
 239 void
 240 expand_des_key(char *obuf, char *inbuf)
 241 {
 242         int i, j;               /* counter in a for loop */
 243         int nbuf[64];                   /* used for hex/key translation */
 244
 245         /*
 246          * leading '0x' or '0X' == hex key
 247          */
 248         if (inbuf[0] == '0' && (inbuf[1] == 'x' || inbuf[1] == 'X')) {
 249                 inbuf = &inbuf[2];
 250                 /*
 251                  * now translate it, bombing on any illegal hex digit
 252                  */
 253                 for (i = 0; inbuf[i] && i < 16; i++)
 254                         if ((nbuf[i] = hex_to_binary((int) inbuf[i], 16)) == -1)
 255                                 des_error("bad hex digit in key");
 256                 while (i < 16)
 257                         nbuf[i++] = 0;
 258                 for (i = 0; i < 8; i++)
 259                         obuf[i] =
 260                             ((nbuf[2*i]&0xf)<<4) | (nbuf[2*i+1]&0xf);
 261                 /* preserve parity bits */
 262                 pflag = 1;
 263                 return;
 264         }
 265         /*
 266          * leading '0b' or '0B' == binary key
 267          */
 268         if (inbuf[0] == '0' && (inbuf[1] == 'b' || inbuf[1] == 'B')) {
 269                 inbuf = &inbuf[2];
 270                 /*
 271                  * now translate it, bombing on any illegal binary digit
 272                  */
 273                 for (i = 0; inbuf[i] && i < 16; i++)
 274                         if ((nbuf[i] = hex_to_binary((int) inbuf[i], 2)) == -1)
 275                                 des_error("bad binary digit in key");
 276                 while (i < 64)
 277                         nbuf[i++] = 0;
 278                 for (i = 0; i < 8; i++)
 279                         for (j = 0; j < 8; j++)
 280                                 obuf[i] = (obuf[i]<<1)|nbuf[8*i+j];
 281                 /* preserve parity bits */
 282                 pflag = 1;
 283                 return;
 284         }
 285         /*
 286          * no special leader -- ASCII
 287          */
 288         strncpy(obuf, inbuf, 8);
 289 }
 290
 291 /*****************
 292  * DES FUNCTIONS *
 293  *****************/
 294 /*
 295  * This sets the DES key and (if you're using the deszip version)
 296  * the direction of the transformation.  This uses the Sun
 297  * to map the 64-bit key onto the 56 bits that the key schedule
 298  * generation routines use: the old way, which just uses the user-
 299  * supplied 64 bits as is, and the new way, which resets the parity
 300  * bit to be the same as the low-order bit in each character.  The
 301  * new way generates a greater variety of key schedules, since many
 302  * systems set the parity (high) bit of each character to 0, and the
 303  * DES ignores the low order bit of each character.
 304  */
 305 void
 306 set_des_key(DES_cblock *buf)            /* key block */
 307 {
 308         int i, j;                       /* counter in a for loop */
 309         int par;                        /* parity counter */
 310
 311         /*
 312          * if the parity is not preserved, flip it
 313          */
 314         if (!pflag) {
 315                 for (i = 0; i < 8; i++) {
 316                         par = 0;
 317                         for (j = 1; j < 8; j++)
 318                                 if ((bits[j] & (*buf)[i]) != 0)
 319                                         par++;
 320                         if ((par & 0x01) == 0x01)
 321                                 (*buf)[i] &= 0x7f;
 322                         else
 323                                 (*buf)[i] = ((*buf)[i] & 0x7f) | 0x80;
 324                 }
 325         }
 326
 327         DES_set_odd_parity(buf);
 328         DES_set_key(buf, &schedule);
 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                         msgbuf[n] ^= ivec[n];
 346                 DES_XFORM((DES_cblock *)msgbuf);
 347                 MEMCPY(ivec, msgbuf, 8);
 348                 return WRITE(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(msgbuf + n, pvec, 8 - n);
 361         msgbuf[7] = n;
 362         for (n = 0; n < 8; n++)
 363                 msgbuf[n] ^= ivec[n];
 364         DES_XFORM((DES_cblock *)msgbuf);
 365         return WRITE(msgbuf, 8, fp);
 366 }
 367
 368 /*
 369  * This decrypts using the Cipher Block Chaining mode of DES
 370  *      msgbuf  I/O buffer
 371  *      fp      input file descriptor
 372  */
 373 int
 374 cbc_decode(char *msgbuf, FILE *fp)
 375 {
 376         DES_cblock inbuf;       /* temp buffer for initialization vector */
 377         int n;          /* number of bytes actually read */
 378         int c;          /* used to test for EOF */
 379         int inverse = 1;        /* 0 to encrypt, 1 to decrypt */
 380
 381         if ((n = READ(msgbuf, 8, fp)) == 8) {
 382                 /*
 383                  * do the transformation
 384                  */
 385                 MEMCPY(inbuf, msgbuf, 8);
 386                 DES_XFORM((DES_cblock *)msgbuf);
 387                 for (c = 0; c < 8; c++)
 388                         msgbuf[c] ^= ivec[c];
 389                 MEMCPY(ivec, inbuf, 8);
 390                 /*
 391                  * if the last one, handle it specially
 392                  */
 393                 if ((c = fgetc(fp)) == EOF) {
 394                         n = msgbuf[7];
 395                         if (n < 0 || n > 7) {
 396                                 des_error("decryption failed (block corrupted)");
 397                                 return EOF;
 398                         }
 399                 } else
 400                         ungetc(c, fp);
 401                 return n;
 402         }
 403         if (n > 0)
 404                 des_error("decryption failed (incomplete block)");
 405         else if (n < 0)
 406                 des_error("cannot read file");
 407         return EOF;
 408 }
 409 #endif  /* DES */