cbc.c revision 1.5
1 /* cbc.c: This file contains the encryption routines for the ed line editor */ 2 /*- 3 * Copyright (c) 1991 The Regents of the University of California. 4 * All rights reserved. 5 * 6 * This code is derived from software contributed to Berkeley by 7 * Matt Bishop of Dartmouth College. 8 * 9 * The United States Government has rights in this work pursuant 10 * to contract no. NAG 2-680 between the National Aeronautics and 11 * Space Administration and Dartmouth College. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 3. All advertising materials mentioning features or use of this software 22 * must display the following acknowledgement: 23 * This product includes software developed by the University of 24 * California, Berkeley and its contributors. 25 * 4. Neither the name of the University nor the names of its contributors 26 * may be used to endorse or promote products derived from this software 27 * without specific prior written permission. 28 * 29 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 32 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 39 * SUCH DAMAGE. 40 */ 41 42 #ifndef lint 43 /*static char sccsid[] = "from: @(#)cbc.c 5.5 (Berkeley) 6/27/91";*/ 44 static char rcsid[] = "$Id: cbc.c,v 1.5 1993/08/01 18:59:49 mycroft Exp $"; 45 #endif /* not lint */ 46 47 /* Author: Matt Bishop 48 * Department of Mathematics and Computer Science 49 * Dartmouth College 50 * Hanover, NH 03755 51 * Email: Matt.Bishop (at) dartmouth.edu 52 * ...!decvax!dartvax!Matt.Bishop 53 * 54 * See Technical Report PCS-TR91-158, Department of Mathematics and Computer 55 * Science, Dartmouth College, for a detailed description of the implemen- 56 * tation and differences between it and Sun's. The DES is described in 57 * FIPS PUB 46, and the modes in FIPS PUB 81 (see either the manual page 58 * or the technical report for a complete reference). 59 */ 60 61 #include <errno.h> 62 #include <pwd.h> 63 #include <unistd.h> 64 #include <stdio.h> 65 #include <ctype.h> 66 #include <stdlib.h> 67 #include <string.h> 68 #include <sys/types.h> 69 70 #include "ed.h" 71 72 /* 73 * Define a divisor for rand() that yields a uniform distribution in the 74 * range 0-255. 75 */ 76 #define RAND_DIV (((unsigned) RAND_MAX + 1) >> 8) 77 78 /* 79 * BSD and System V systems offer special library calls that do 80 * block moves and fills, so if possible we take advantage of them 81 */ 82 #define MEMCPY(dest,src,len) memcpy((dest),(src),(len)) 83 #define MEMZERO(dest,len) memset((dest), 0, (len)) 84 85 /* Hide the calls to the primitive encryption routines. */ 86 #define DES_KEY(buf) \ 87 if (des_setkey(buf)) \ 88 err("des_setkey"); 89 #define DES_XFORM(buf) \ 90 if (des_cipher(buf, buf, 0L, (inverse ? -1 : 1))) \ 91 err("des_cipher"); 92 93 /* 94 * read/write - no error checking 95 */ 96 #define READ(buf, n, fp) fread(buf, sizeof(char), n, fp) 97 #define WRITE(buf, n, fp) fwrite(buf, sizeof(char), n, fp) 98 99 /* 100 * some things to make references easier 101 */ 102 typedef char Desbuf[8]; 103 #define CHAR(x,i) (x[i]) 104 #define UCHAR(x,i) (x[i]) 105 #define BUFFER(x) (x) 106 #define UBUFFER(x) (x) 107 108 /* 109 * global variables and related macros 110 */ 111 112 enum { /* encrypt, decrypt, authenticate */ 113 MODE_ENCRYPT, MODE_DECRYPT, MODE_AUTHENTICATE 114 } mode = MODE_ENCRYPT; 115 116 Desbuf ivec; /* initialization vector */ 117 Desbuf pvec; /* padding vector */ 118 char bits[] = { /* used to extract bits from a char */ 119 '\200', '\100', '\040', '\020', '\010', '\004', '\002', '\001' 120 }; 121 int pflag; /* 1 to preserve parity bits */ 122 123 char des_buf[8]; /* shared buffer for desgetc/desputc */ 124 int des_ct = 0; /* count for desgetc/desputc */ 125 int des_n = 0; /* index for desputc/desgetc */ 126 127 128 /* desinit: initialize DES */ 129 void 130 desinit() 131 { 132 #ifdef DES 133 int i; 134 135 des_ct = des_n = 0; 136 137 /* initialize the initialization vctor */ 138 MEMZERO(ivec, 8); 139 140 /* intialize the padding vector */ 141 srand((unsigned) time((time_t *) 0)); 142 for (i = 0; i < 8; i++) 143 CHAR(pvec, i) = (char) (rand()/RAND_DIV); 144 #endif 145 } 146 147 148 /* desgetc: return next char in an encrypted file */ 149 desgetc(fp) 150 FILE *fp; 151 { 152 #ifdef DES 153 if (des_n >= des_ct) { 154 des_n = 0; 155 des_ct = cbcdec(des_buf, fp); 156 } 157 return (des_ct > 0) ? des_buf[des_n++] : EOF; 158 #endif 159 } 160 161 162 /* desputc: write a char to an encrypted file; return char written */ 163 desputc(c, fp) 164 int c; 165 FILE *fp; 166 { 167 #ifdef DES 168 if (des_n == sizeof des_buf) { 169 des_ct = cbcenc(des_buf, des_n, fp); 170 des_n = 0; 171 } 172 return (des_ct >= 0) ? (des_buf[des_n++] = c) : EOF; 173 #endif 174 } 175 176 177 /* desflush: flush an encrypted file's output; return status */ 178 desflush(fp) 179 FILE *fp; 180 { 181 #ifdef DES 182 if (des_n == sizeof des_buf) { 183 des_ct = cbcenc(des_buf, des_n, fp); 184 des_n = 0; 185 } 186 return (des_ct >= 0 && cbcenc(des_buf, des_n, fp) >= 0) ? 0 : EOF; 187 #endif 188 } 189 190 #ifdef DES 191 /* 192 * get keyword from tty or stdin 193 */ 194 getkey() 195 { 196 register char *p; /* used to obtain the key */ 197 Desbuf msgbuf; /* I/O buffer */ 198 199 /* 200 * get the key 201 */ 202 if (*(p = getpass("Enter key: "))) { 203 204 /* 205 * copy it, nul-padded, into the key area 206 */ 207 cvtkey(BUFFER(msgbuf), p); 208 MEMZERO(p, _PASSWORD_LEN); 209 makekey(msgbuf); 210 MEMZERO(msgbuf, sizeof msgbuf); 211 return 1; 212 } 213 return 0; 214 } 215 216 217 extern char errmsg[]; 218 219 /* 220 * print a warning message and, possibly, terminate 221 */ 222 void 223 err(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 tobinhex(c, radix) 233 int c; /* char to be converted */ 234 int radix; /* base (2 to 16) */ 235 { 236 switch(c) { 237 case '0': return(0x0); 238 case '1': return(0x1); 239 case '2': return(radix > 2 ? 0x2 : -1); 240 case '3': return(radix > 3 ? 0x3 : -1); 241 case '4': return(radix > 4 ? 0x4 : -1); 242 case '5': return(radix > 5 ? 0x5 : -1); 243 case '6': return(radix > 6 ? 0x6 : -1); 244 case '7': return(radix > 7 ? 0x7 : -1); 245 case '8': return(radix > 8 ? 0x8 : -1); 246 case '9': return(radix > 9 ? 0x9 : -1); 247 case 'A': case 'a': return(radix > 10 ? 0xa : -1); 248 case 'B': case 'b': return(radix > 11 ? 0xb : -1); 249 case 'C': case 'c': return(radix > 12 ? 0xc : -1); 250 case 'D': case 'd': return(radix > 13 ? 0xd : -1); 251 case 'E': case 'e': return(radix > 14 ? 0xe : -1); 252 case 'F': case 'f': return(radix > 15 ? 0xf : -1); 253 } 254 /* 255 * invalid character 256 */ 257 return(-1); 258 } 259 260 /* 261 * convert the key to a bit pattern 262 */ 263 void 264 cvtkey(obuf, ibuf) 265 char *obuf; /* bit pattern */ 266 char *ibuf; /* the key itself */ 267 { 268 register int i, j; /* counter in a for loop */ 269 int nbuf[64]; /* used for hex/key translation */ 270 271 /* 272 * leading '0x' or '0X' == hex key 273 */ 274 if (ibuf[0] == '0' && (ibuf[1] == 'x' || ibuf[1] == 'X')) { 275 ibuf = &ibuf[2]; 276 /* 277 * now translate it, bombing on any illegal hex digit 278 */ 279 for (i = 0; ibuf[i] && i < 16; i++) 280 if ((nbuf[i] = tobinhex((int) ibuf[i], 16)) == -1) 281 err("bad hex digit in key"); 282 while (i < 16) 283 nbuf[i++] = 0; 284 for (i = 0; i < 8; i++) 285 obuf[i] = 286 ((nbuf[2*i]&0xf)<<4) | (nbuf[2*i+1]&0xf); 287 /* preserve parity bits */ 288 pflag = 1; 289 return; 290 } 291 /* 292 * leading '0b' or '0B' == binary key 293 */ 294 if (ibuf[0] == '0' && (ibuf[1] == 'b' || ibuf[1] == 'B')) { 295 ibuf = &ibuf[2]; 296 /* 297 * now translate it, bombing on any illegal binary digit 298 */ 299 for (i = 0; ibuf[i] && i < 16; i++) 300 if ((nbuf[i] = tobinhex((int) ibuf[i], 2)) == -1) 301 err("bad binary digit in key"); 302 while (i < 64) 303 nbuf[i++] = 0; 304 for (i = 0; i < 8; i++) 305 for (j = 0; j < 8; j++) 306 obuf[i] = (obuf[i]<<1)|nbuf[8*i+j]; 307 /* preserve parity bits */ 308 pflag = 1; 309 return; 310 } 311 /* 312 * no special leader -- ASCII 313 */ 314 (void)strncpy(obuf, ibuf, 8); 315 } 316 317 /***************** 318 * DES FUNCTIONS * 319 *****************/ 320 /* 321 * This sets the DES key and (if you're using the deszip version) 322 * the direction of the transformation. This uses the Sun 323 * to map the 64-bit key onto the 56 bits that the key schedule 324 * generation routines use: the old way, which just uses the user- 325 * supplied 64 bits as is, and the new way, which resets the parity 326 * bit to be the same as the low-order bit in each character. The 327 * new way generates a greater variety of key schedules, since many 328 * systems set the parity (high) bit of each character to 0, and the 329 * DES ignores the low order bit of each character. 330 */ 331 void 332 makekey(buf) 333 Desbuf buf; /* key block */ 334 { 335 register int i, j; /* counter in a for loop */ 336 register int par; /* parity counter */ 337 338 /* 339 * if the parity is not preserved, flip it 340 */ 341 if (!pflag) { 342 for (i = 0; i < 8; i++) { 343 par = 0; 344 for (j = 1; j < 8; j++) 345 if ((bits[j]&UCHAR(buf, i)) != 0) 346 par++; 347 if ((par&01) == 01) 348 UCHAR(buf, i) = UCHAR(buf, i)&0177; 349 else 350 UCHAR(buf, i) = (UCHAR(buf, i)&0177)|0200; 351 } 352 } 353 354 DES_KEY(UBUFFER(buf)); 355 } 356 357 358 /* 359 * This encrypts using the Cipher Block Chaining mode of DES 360 */ 361 cbcenc(msgbuf, n, fp) 362 char *msgbuf; 363 int n; 364 FILE *fp; 365 { 366 int inverse = 0; /* 0 to encrypt, 1 to decrypt */ 367 368 /* 369 * do the transformation 370 */ 371 if (n == 8) { 372 for (n = 0; n < 8; n++) 373 CHAR(msgbuf, n) ^= CHAR(ivec, n); 374 DES_XFORM(UBUFFER(msgbuf)); 375 MEMCPY(BUFFER(ivec), BUFFER(msgbuf), 8); 376 return WRITE(BUFFER(msgbuf), 8, fp); 377 } 378 /* 379 * at EOF or last block -- in either case, the last byte contains 380 * the character representation of the number of bytes in it 381 */ 382 /* 383 MEMZERO(msgbuf + n, 8 - n); 384 */ 385 /* 386 * Pad the last block randomly 387 */ 388 (void)MEMCPY(BUFFER(msgbuf + n), BUFFER(pvec), 8 - n); 389 CHAR(msgbuf, 7) = n; 390 for (n = 0; n < 8; n++) 391 CHAR(msgbuf, n) ^= CHAR(ivec, n); 392 DES_XFORM(UBUFFER(msgbuf)); 393 return WRITE(BUFFER(msgbuf), 8, fp); 394 } 395 396 /* 397 * This decrypts using the Cipher Block Chaining mode of DES 398 */ 399 cbcdec(msgbuf, fp) 400 char *msgbuf; /* I/O buffer */ 401 FILE *fp; /* input file descriptor */ 402 { 403 Desbuf ibuf; /* temp buffer for initialization vector */ 404 register int n; /* number of bytes actually read */ 405 register int c; /* used to test for EOF */ 406 int inverse = 1; /* 0 to encrypt, 1 to decrypt */ 407 408 if ((n = READ(BUFFER(msgbuf), 8, fp)) == 8) { 409 /* 410 * do the transformation 411 */ 412 MEMCPY(BUFFER(ibuf), BUFFER(msgbuf), 8); 413 DES_XFORM(UBUFFER(msgbuf)); 414 for (c = 0; c < 8; c++) 415 UCHAR(msgbuf, c) ^= UCHAR(ivec, c); 416 MEMCPY(BUFFER(ivec), BUFFER(ibuf), 8); 417 /* 418 * if the last one, handle it specially 419 */ 420 if ((c = fgetc(fp)) == EOF) { 421 n = CHAR(msgbuf, 7); 422 if (n < 0 || n > 7) { 423 err("decryption failed (block corrupted)"); 424 return EOF; 425 } 426 } else 427 (void)ungetc(c, fp); 428 return n; 429 } 430 if (n > 0) 431 err("decryption failed (incomplete block)"); 432 else if (n < 0) 433 err("cannot read file"); 434 return EOF; 435 } 436 #endif /* DES */ 437
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