cbc.c revision 1.13
1 /* $NetBSD: cbc.c,v 1.13 1998/07/28 05:46:20 mycroft Exp $ */ 2 3 /* cbc.c: This file contains the encryption routines for the ed line editor */ 4 /*- 5 * Copyright (c) 1993 The Regents of the University of California. 6 * All rights reserved. 7 * 8 * Copyright (c) 1993 Andrew Moore, Talke Studio. 9 * All rights reserved. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. All advertising materials mentioning features or use of this software 20 * must display the following acknowledgement: 21 * This product includes software developed by the University of 22 * California, Berkeley and its contributors. 23 * 4. Neither the name of the University nor the names of its contributors 24 * may be used to endorse or promote products derived from this software 25 * without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 37 * SUCH DAMAGE. 38 * 39 * from: @(#)bdes.c 5.5 (Berkeley) 6/27/91 40 */ 41 42 #include <sys/cdefs.h> 43 #ifndef lint 44 #if 0 45 static char *rcsid = "@(#)cbc.c,v 1.2 1994/02/01 00:34:36 alm Exp"; 46 #else 47 __RCSID("$NetBSD: cbc.c,v 1.13 1998/07/28 05:46:20 mycroft Exp $"); 48 #endif 49 #endif /* not lint */ 50 51 #include <sys/types.h> 52 #include <ctype.h> 53 #include <errno.h> 54 #include <pwd.h> 55 #ifdef DES 56 #include <time.h> 57 #endif 58 59 #include "ed.h" 60 61 62 /* 63 * Define a divisor for rand() that yields a uniform distribution in the 64 * range 0-255. 65 */ 66 #define RAND_DIV (((unsigned) RAND_MAX + 1) >> 8) 67 68 /* 69 * BSD and System V systems offer special library calls that do 70 * block move_liness and fills, so if possible we take advantage of them 71 */ 72 #define MEMCPY(dest,src,len) memcpy((dest),(src),(len)) 73 #define MEMZERO(dest,len) memset((dest), 0, (len)) 74 75 /* Hide the calls to the primitive encryption routines. */ 76 #define DES_KEY(buf) \ 77 if (des_setkey(buf)) \ 78 des_error("des_setkey"); 79 #define DES_XFORM(buf) \ 80 if (des_cipher(buf, buf, 0L, (inverse ? -1 : 1))) \ 81 des_error("des_cipher"); 82 83 /* 84 * read/write - no error checking 85 */ 86 #define READ(buf, n, fp) fread(buf, sizeof(char), n, fp) 87 #define WRITE(buf, n, fp) fwrite(buf, sizeof(char), n, fp) 88 89 /* 90 * some things to make references easier 91 */ 92 typedef char Desbuf[8]; 93 #define CHAR(x,i) (x[i]) 94 #define UCHAR(x,i) (x[i]) 95 #define BUFFER(x) (x) 96 #define UBUFFER(x) (x) 97 98 #ifdef DES 99 /* 100 * global variables and related macros 101 */ 102 103 enum { /* encrypt, decrypt, authenticate */ 104 MODE_ENCRYPT, MODE_DECRYPT, MODE_AUTHENTICATE 105 } mode = MODE_ENCRYPT; 106 107 Desbuf ivec; /* initialization vector */ 108 Desbuf pvec; /* padding vector */ 109 char bits[] = { /* used to extract bits from a char */ 110 '\200', '\100', '\040', '\020', '\010', '\004', '\002', '\001' 111 }; 112 int pflag; /* 1 to preserve parity bits */ 113 114 unsigned char des_buf[8]; /* shared buffer for get_des_char/put_des_char */ 115 int des_ct = 0; /* count for get_des_char/put_des_char */ 116 int des_n = 0; /* index for put_des_char/get_des_char */ 117 #endif 118 119 120 /* init_des_cipher: initialize DES */ 121 void 122 init_des_cipher() 123 { 124 #ifdef DES 125 int i; 126 127 des_ct = des_n = 0; 128 129 /* initialize the initialization vctor */ 130 MEMZERO(ivec, 8); 131 132 /* intialize the padding vector */ 133 srand((unsigned) time((time_t *) 0)); 134 for (i = 0; i < 8; i++) 135 CHAR(pvec, i) = (char) (rand()/RAND_DIV); 136 #endif 137 } 138 139 140 /* get_des_char: return next char in an encrypted file */ 141 int 142 get_des_char(fp) 143 FILE *fp; 144 { 145 #ifdef DES 146 if (des_n >= des_ct) { 147 des_n = 0; 148 des_ct = cbc_decode(des_buf, fp); 149 } 150 return (des_ct > 0) ? des_buf[des_n++] : EOF; 151 #else 152 return EOF; 153 #endif 154 } 155 156 157 /* put_des_char: write a char to an encrypted file; return char written */ 158 int 159 put_des_char(c, fp) 160 int c; 161 FILE *fp; 162 { 163 #ifdef DES 164 if (des_n == sizeof des_buf) { 165 des_ct = cbc_encode(des_buf, des_n, fp); 166 des_n = 0; 167 } 168 return (des_ct >= 0) ? (des_buf[des_n++] = c) : EOF; 169 #else 170 return EOF; 171 #endif 172 } 173 174 175 /* flush_des_file: flush an encrypted file's output; return status */ 176 int 177 flush_des_file(fp) 178 FILE *fp; 179 { 180 #ifdef DES 181 if (des_n == sizeof des_buf) { 182 des_ct = cbc_encode(des_buf, des_n, fp); 183 des_n = 0; 184 } 185 return (des_ct >= 0 && cbc_encode(des_buf, des_n, fp) >= 0) ? 0 : EOF; 186 #else 187 return EOF; 188 #endif 189 } 190 191 #ifdef DES 192 /* 193 * get keyword from tty or stdin 194 */ 195 int 196 get_keyword() 197 { 198 char *p; /* used to obtain the key */ 199 Desbuf msgbuf; /* I/O buffer */ 200 201 /* 202 * get the key 203 */ 204 if (*(p = getpass("Enter key: "))) { 205 206 /* 207 * copy it, nul-padded, into the key area 208 */ 209 expand_des_key(BUFFER(msgbuf), p); 210 MEMZERO(p, _PASSWORD_LEN); 211 set_des_key(msgbuf); 212 MEMZERO(msgbuf, sizeof msgbuf); 213 return 1; 214 } 215 return 0; 216 } 217 218 219 /* 220 * print a warning message and, possibly, terminate 221 */ 222 void 223 des_error(s) 224 char *s; /* the message */ 225 { 226 (void)sprintf(errmsg, "%s", s ? s : strerror(errno)); 227 } 228 229 /* 230 * map a hex character to an integer 231 */ 232 int 233 hex_to_binary(c, radix) 234 int c; /* char to be converted */ 235 int radix; /* base (2 to 16) */ 236 { 237 switch(c) { 238 case '0': return(0x0); 239 case '1': return(0x1); 240 case '2': return(radix > 2 ? 0x2 : -1); 241 case '3': return(radix > 3 ? 0x3 : -1); 242 case '4': return(radix > 4 ? 0x4 : -1); 243 case '5': return(radix > 5 ? 0x5 : -1); 244 case '6': return(radix > 6 ? 0x6 : -1); 245 case '7': return(radix > 7 ? 0x7 : -1); 246 case '8': return(radix > 8 ? 0x8 : -1); 247 case '9': return(radix > 9 ? 0x9 : -1); 248 case 'A': case 'a': return(radix > 10 ? 0xa : -1); 249 case 'B': case 'b': return(radix > 11 ? 0xb : -1); 250 case 'C': case 'c': return(radix > 12 ? 0xc : -1); 251 case 'D': case 'd': return(radix > 13 ? 0xd : -1); 252 case 'E': case 'e': return(radix > 14 ? 0xe : -1); 253 case 'F': case 'f': return(radix > 15 ? 0xf : -1); 254 } 255 /* 256 * invalid character 257 */ 258 return(-1); 259 } 260 261 /* 262 * convert the key to a bit pattern 263 */ 264 void 265 expand_des_key(obuf, ibuf) 266 char *obuf; /* bit pattern */ 267 char *ibuf; /* the key itself */ 268 { 269 int i, j; /* counter in a for loop */ 270 int nbuf[64]; /* used for hex/key translation */ 271 272 /* 273 * leading '0x' or '0X' == hex key 274 */ 275 if (ibuf[0] == '0' && (ibuf[1] == 'x' || ibuf[1] == 'X')) { 276 ibuf = &ibuf[2]; 277 /* 278 * now translate it, bombing on any illegal hex digit 279 */ 280 for (i = 0; ibuf[i] && i < 16; i++) 281 if ((nbuf[i] = hex_to_binary((int) ibuf[i], 16)) == -1) 282 des_error("bad hex digit in key"); 283 while (i < 16) 284 nbuf[i++] = 0; 285 for (i = 0; i < 8; i++) 286 obuf[i] = 287 ((nbuf[2*i]&0xf)<<4) | (nbuf[2*i+1]&0xf); 288 /* preserve parity bits */ 289 pflag = 1; 290 return; 291 } 292 /* 293 * leading '0b' or '0B' == binary key 294 */ 295 if (ibuf[0] == '0' && (ibuf[1] == 'b' || ibuf[1] == 'B')) { 296 ibuf = &ibuf[2]; 297 /* 298 * now translate it, bombing on any illegal binary digit 299 */ 300 for (i = 0; ibuf[i] && i < 16; i++) 301 if ((nbuf[i] = hex_to_binary((int) ibuf[i], 2)) == -1) 302 des_error("bad binary digit in key"); 303 while (i < 64) 304 nbuf[i++] = 0; 305 for (i = 0; i < 8; i++) 306 for (j = 0; j < 8; j++) 307 obuf[i] = (obuf[i]<<1)|nbuf[8*i+j]; 308 /* preserve parity bits */ 309 pflag = 1; 310 return; 311 } 312 /* 313 * no special leader -- ASCII 314 */ 315 (void)strncpy(obuf, ibuf, 8); 316 } 317 318 /***************** 319 * DES FUNCTIONS * 320 *****************/ 321 /* 322 * This sets the DES key and (if you're using the deszip version) 323 * the direction of the transformation. This uses the Sun 324 * to map the 64-bit key onto the 56 bits that the key schedule 325 * generation routines use: the old way, which just uses the user- 326 * supplied 64 bits as is, and the new way, which resets the parity 327 * bit to be the same as the low-order bit in each character. The 328 * new way generates a greater variety of key schedules, since many 329 * systems set the parity (high) bit of each character to 0, and the 330 * DES ignores the low order bit of each character. 331 */ 332 void 333 set_des_key(buf) 334 Desbuf buf; /* key block */ 335 { 336 int i, j; /* counter in a for loop */ 337 int par; /* parity counter */ 338 339 /* 340 * if the parity is not preserved, flip it 341 */ 342 if (!pflag) { 343 for (i = 0; i < 8; i++) { 344 par = 0; 345 for (j = 1; j < 8; j++) 346 if ((bits[j]&UCHAR(buf, i)) != 0) 347 par++; 348 if ((par&01) == 01) 349 UCHAR(buf, i) = UCHAR(buf, i)&0177; 350 else 351 UCHAR(buf, i) = (UCHAR(buf, i)&0177)|0200; 352 } 353 } 354 355 DES_KEY(UBUFFER(buf)); 356 } 357 358 359 /* 360 * This encrypts using the Cipher Block Chaining mode of DES 361 */ 362 int 363 cbc_encode(msgbuf, n, fp) 364 char *msgbuf; 365 int n; 366 FILE *fp; 367 { 368 int inverse = 0; /* 0 to encrypt, 1 to decrypt */ 369 370 /* 371 * do the transformation 372 */ 373 if (n == 8) { 374 for (n = 0; n < 8; n++) 375 CHAR(msgbuf, n) ^= CHAR(ivec, n); 376 DES_XFORM(UBUFFER(msgbuf)); 377 MEMCPY(BUFFER(ivec), BUFFER(msgbuf), 8); 378 return WRITE(BUFFER(msgbuf), 8, fp); 379 } 380 /* 381 * at EOF or last block -- in either case, the last byte contains 382 * the character representation of the number of bytes in it 383 */ 384 /* 385 MEMZERO(msgbuf + n, 8 - n); 386 */ 387 /* 388 * Pad the last block randomly 389 */ 390 (void)MEMCPY(BUFFER(msgbuf + n), BUFFER(pvec), 8 - n); 391 CHAR(msgbuf, 7) = n; 392 for (n = 0; n < 8; n++) 393 CHAR(msgbuf, n) ^= CHAR(ivec, n); 394 DES_XFORM(UBUFFER(msgbuf)); 395 return WRITE(BUFFER(msgbuf), 8, fp); 396 } 397 398 /* 399 * This decrypts using the Cipher Block Chaining mode of DES 400 */ 401 int 402 cbc_decode(msgbuf, fp) 403 char *msgbuf; /* I/O buffer */ 404 FILE *fp; /* input file descriptor */ 405 { 406 Desbuf ibuf; /* temp buffer for initialization vector */ 407 int n; /* number of bytes actually read */ 408 int c; /* used to test for EOF */ 409 int inverse = 1; /* 0 to encrypt, 1 to decrypt */ 410 411 if ((n = READ(BUFFER(msgbuf), 8, fp)) == 8) { 412 /* 413 * do the transformation 414 */ 415 MEMCPY(BUFFER(ibuf), BUFFER(msgbuf), 8); 416 DES_XFORM(UBUFFER(msgbuf)); 417 for (c = 0; c < 8; c++) 418 UCHAR(msgbuf, c) ^= UCHAR(ivec, c); 419 MEMCPY(BUFFER(ivec), BUFFER(ibuf), 8); 420 /* 421 * if the last one, handle it specially 422 */ 423 if ((c = fgetc(fp)) == EOF) { 424 n = CHAR(msgbuf, 7); 425 if (n < 0 || n > 7) { 426 des_error("decryption failed (block corrupted)"); 427 return EOF; 428 } 429 } else 430 (void)ungetc(c, fp); 431 return n; 432 } 433 if (n > 0) 434 des_error("decryption failed (incomplete block)"); 435 else if (n < 0) 436 des_error("cannot read file"); 437 return EOF; 438 } 439 #endif /* DES */ 440
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