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[] = "@(#)cbc.c 5.5 (Berkeley) 6/27/91"; 44 #endif /* not lint */ 45 46 /* Author: Matt Bishop 47 * Department of Mathematics and Computer Science 48 * Dartmouth College 49 * Hanover, NH 03755 50 * Email: Matt.Bishop@dartmouth.edu 51 * ...!decvax!dartvax!Matt.Bishop 52 * 53 * See Technical Report PCS-TR91-158, Department of Mathematics and Computer 54 * Science, Dartmouth College, for a detailed description of the implemen- 55 * tation and differences between it and Sun's. The DES is described in 56 * FIPS PUB 46, and the modes in FIPS PUB 81 (see either the manual page 57 * or the technical report for a complete reference). 58 */ 59 60 #include <errno.h> 61 #include <pwd.h> 62 #include <unistd.h> 63 #include <stdio.h> 64 #include <ctype.h> 65 #include <stdlib.h> 66 #include <string.h> 67 #include <sys/types.h> 68 69 #include "ed.h" 70 71 /* 72 * Define a divisor for rand() that yields a uniform distribution in the 73 * range 0-255. 74 */ 75 #define RAND_DIV (((unsigned) RAND_MAX + 1) >> 8) 76 77 /* 78 * BSD and System V systems offer special library calls that do 79 * block moves and fills, so if possible we take advantage of them 80 */ 81 #define MEMCPY(dest,src,len) memcpy((dest),(src),(len)) 82 #define MEMZERO(dest,len) memset((dest), 0, (len)) 83 84 /* Hide the calls to the primitive encryption routines. */ 85 #define DES_KEY(buf) \ 86 if (des_setkey(buf)) \ 87 err("des_setkey"); 88 #define DES_XFORM(buf) \ 89 if (des_cipher(buf, buf, 0L, (inverse ? -1 : 1))) \ 90 err("des_cipher"); 91 92 /* 93 * read/write - no error checking 94 */ 95 #define READ(buf, n, fp) fread(buf, sizeof(char), n, fp) 96 #define WRITE(buf, n, fp) fwrite(buf, sizeof(char), n, fp) 97 98 /* 99 * some things to make references easier 100 */ 101 typedef char Desbuf[8]; 102 #define CHAR(x,i) (x[i]) 103 #define UCHAR(x,i) (x[i]) 104 #define BUFFER(x) (x) 105 #define UBUFFER(x) (x) 106 107 /* 108 * global variables and related macros 109 */ 110 111 enum { /* encrypt, decrypt, authenticate */ 112 MODE_ENCRYPT, MODE_DECRYPT, MODE_AUTHENTICATE 113 } mode = MODE_ENCRYPT; 114 115 Desbuf ivec; /* initialization vector */ 116 Desbuf pvec; /* padding vector */ 117 char bits[] = { /* used to extract bits from a char */ 118 '\200', '\100', '\040', '\020', '\010', '\004', '\002', '\001' 119 }; 120 int pflag; /* 1 to preserve parity bits */ 121 122 char des_buf[8]; /* shared buffer for desgetc/desputc */ 123 int des_ct = 0; /* count for desgetc/desputc */ 124 int des_n = 0; /* index for desputc/desgetc */ 125 126 127 /* desinit: initialize DES */ 128 void 129 desinit() 130 { 131 #ifdef DES 132 int i; 133 134 des_ct = des_n = 0; 135 136 /* initialize the initialization vctor */ 137 MEMZERO(ivec, 8); 138 139 /* intialize the padding vector */ 140 srand((unsigned) time((time_t *) 0)); 141 for (i = 0; i < 8; i++) 142 CHAR(pvec, i) = (char) (rand()/RAND_DIV); 143 #endif 144 } 145 146 147 /* desgetc: return next char in an encrypted file */ 148 desgetc(fp) 149 FILE *fp; 150 { 151 #ifdef DES 152 if (des_n >= des_ct) { 153 des_n = 0; 154 des_ct = cbcdec(des_buf, fp); 155 } 156 return (des_ct > 0) ? des_buf[des_n++] : EOF; 157 #endif 158 } 159 160 161 /* desputc: write a char to an encrypted file; return char written */ 162 desputc(c, fp) 163 int c; 164 FILE *fp; 165 { 166 #ifdef DES 167 if (des_n == sizeof des_buf) { 168 des_ct = cbcenc(des_buf, des_n, fp); 169 des_n = 0; 170 } 171 return (des_ct >= 0) ? (des_buf[des_n++] = c) : EOF; 172 #endif 173 } 174 175 176 /* desflush: flush an encrypted file's output; return status */ 177 desflush(fp) 178 FILE *fp; 179 { 180 #ifdef DES 181 if (des_n == sizeof des_buf) { 182 des_ct = cbcenc(des_buf, des_n, fp); 183 des_n = 0; 184 } 185 return (des_ct >= 0 && cbcenc(des_buf, des_n, fp) >= 0) ? 0 : EOF; 186 #endif 187 } 188 189 #ifdef DES 190 /* 191 * get keyword from tty or stdin 192 */ 193 getkey() 194 { 195 register char *p; /* used to obtain the key */ 196 Desbuf msgbuf; /* I/O buffer */ 197 198 /* 199 * get the key 200 */ 201 if (*(p = getpass("Enter key: "))) { 202 203 /* 204 * copy it, nul-padded, into the key area 205 */ 206 cvtkey(BUFFER(msgbuf), p); 207 MEMZERO(p, _PASSWORD_LEN); 208 makekey(msgbuf); 209 MEMZERO(msgbuf, sizeof msgbuf); 210 return 1; 211 } 212 return 0; 213 } 214 215 216 extern char errmsg[]; 217 218 /* 219 * print a warning message and, possibly, terminate 220 */ 221 void 222 err(s) 223 char *s; /* the message */ 224 { 225 (void)sprintf(errmsg, "%s", s ? s : strerror(errno)); 226 } 227 228 /* 229 * map a hex character to an integer 230 */ 231 tobinhex(c, radix) 232 int c; /* char to be converted */ 233 int radix; /* base (2 to 16) */ 234 { 235 switch(c) { 236 case '0': return(0x0); 237 case '1': return(0x1); 238 case '2': return(radix > 2 ? 0x2 : -1); 239 case '3': return(radix > 3 ? 0x3 : -1); 240 case '4': return(radix > 4 ? 0x4 : -1); 241 case '5': return(radix > 5 ? 0x5 : -1); 242 case '6': return(radix > 6 ? 0x6 : -1); 243 case '7': return(radix > 7 ? 0x7 : -1); 244 case '8': return(radix > 8 ? 0x8 : -1); 245 case '9': return(radix > 9 ? 0x9 : -1); 246 case 'A': case 'a': return(radix > 10 ? 0xa : -1); 247 case 'B': case 'b': return(radix > 11 ? 0xb : -1); 248 case 'C': case 'c': return(radix > 12 ? 0xc : -1); 249 case 'D': case 'd': return(radix > 13 ? 0xd : -1); 250 case 'E': case 'e': return(radix > 14 ? 0xe : -1); 251 case 'F': case 'f': return(radix > 15 ? 0xf : -1); 252 } 253 /* 254 * invalid character 255 */ 256 return(-1); 257 } 258 259 /* 260 * convert the key to a bit pattern 261 */ 262 void 263 cvtkey(obuf, ibuf) 264 char *obuf; /* bit pattern */ 265 char *ibuf; /* the key itself */ 266 { 267 register int i, j; /* counter in a for loop */ 268 int nbuf[64]; /* used for hex/key translation */ 269 270 /* 271 * leading '0x' or '0X' == hex key 272 */ 273 if (ibuf[0] == '0' && (ibuf[1] == 'x' || ibuf[1] == 'X')) { 274 ibuf = &ibuf[2]; 275 /* 276 * now translate it, bombing on any illegal hex digit 277 */ 278 for (i = 0; ibuf[i] && i < 16; i++) 279 if ((nbuf[i] = tobinhex((int) ibuf[i], 16)) == -1) 280 err("bad hex digit in key"); 281 while (i < 16) 282 nbuf[i++] = 0; 283 for (i = 0; i < 8; i++) 284 obuf[i] = 285 ((nbuf[2*i]&0xf)<<4) | (nbuf[2*i+1]&0xf); 286 /* preserve parity bits */ 287 pflag = 1; 288 return; 289 } 290 /* 291 * leading '0b' or '0B' == binary key 292 */ 293 if (ibuf[0] == '0' && (ibuf[1] == 'b' || ibuf[1] == 'B')) { 294 ibuf = &ibuf[2]; 295 /* 296 * now translate it, bombing on any illegal binary digit 297 */ 298 for (i = 0; ibuf[i] && i < 16; i++) 299 if ((nbuf[i] = tobinhex((int) ibuf[i], 2)) == -1) 300 err("bad binary digit in key"); 301 while (i < 64) 302 nbuf[i++] = 0; 303 for (i = 0; i < 8; i++) 304 for (j = 0; j < 8; j++) 305 obuf[i] = (obuf[i]<<1)|nbuf[8*i+j]; 306 /* preserve parity bits */ 307 pflag = 1; 308 return; 309 } 310 /* 311 * no special leader -- ASCII 312 */ 313 (void)strncpy(obuf, ibuf, 8); 314 } 315 316 /***************** 317 * DES FUNCTIONS * 318 *****************/ 319 /* 320 * This sets the DES key and (if you're using the deszip version) 321 * the direction of the transformation. This uses the Sun 322 * to map the 64-bit key onto the 56 bits that the key schedule 323 * generation routines use: the old way, which just uses the user- 324 * supplied 64 bits as is, and the new way, which resets the parity 325 * bit to be the same as the low-order bit in each character. The 326 * new way generates a greater variety of key schedules, since many 327 * systems set the parity (high) bit of each character to 0, and the 328 * DES ignores the low order bit of each character. 329 */ 330 void 331 makekey(buf) 332 Desbuf buf; /* key block */ 333 { 334 register int i, j; /* counter in a for loop */ 335 register int par; /* parity counter */ 336 337 /* 338 * if the parity is not preserved, flip it 339 */ 340 if (!pflag) { 341 for (i = 0; i < 8; i++) { 342 par = 0; 343 for (j = 1; j < 8; j++) 344 if ((bits[j]&UCHAR(buf, i)) != 0) 345 par++; 346 if ((par&01) == 01) 347 UCHAR(buf, i) = UCHAR(buf, i)&0177; 348 else 349 UCHAR(buf, i) = (UCHAR(buf, i)&0177)|0200; 350 } 351 } 352 353 DES_KEY(UBUFFER(buf)); 354 } 355 356 357 /* 358 * This encrypts using the Cipher Block Chaining mode of DES 359 */ 360 cbcenc(msgbuf, n, fp) 361 char *msgbuf; 362 int n; 363 FILE *fp; 364 { 365 int inverse = 0; /* 0 to encrypt, 1 to decrypt */ 366 367 /* 368 * do the transformation 369 */ 370 if (n == 8) { 371 for (n = 0; n < 8; n++) 372 CHAR(msgbuf, n) ^= CHAR(ivec, n); 373 DES_XFORM(UBUFFER(msgbuf)); 374 MEMCPY(BUFFER(ivec), BUFFER(msgbuf), 8); 375 return WRITE(BUFFER(msgbuf), 8, fp); 376 } 377 /* 378 * at EOF or last block -- in either case, the last byte contains 379 * the character representation of the number of bytes in it 380 */ 381 /* 382 MEMZERO(msgbuf + n, 8 - n); 383 */ 384 /* 385 * Pad the last block randomly 386 */ 387 (void)MEMCPY(BUFFER(msgbuf + n), BUFFER(pvec), 8 - n); 388 CHAR(msgbuf, 7) = n; 389 for (n = 0; n < 8; n++) 390 CHAR(msgbuf, n) ^= CHAR(ivec, n); 391 DES_XFORM(UBUFFER(msgbuf)); 392 return WRITE(BUFFER(msgbuf), 8, fp); 393 } 394 395 /* 396 * This decrypts using the Cipher Block Chaining mode of DES 397 */ 398 cbcdec(msgbuf, fp) 399 char *msgbuf; /* I/O buffer */ 400 FILE *fp; /* input file descriptor */ 401 { 402 Desbuf ibuf; /* temp buffer for initialization vector */ 403 register int n; /* number of bytes actually read */ 404 register int c; /* used to test for EOF */ 405 int inverse = 1; /* 0 to encrypt, 1 to decrypt */ 406 407 if ((n = READ(BUFFER(msgbuf), 8, fp)) == 8) { 408 /* 409 * do the transformation 410 */ 411 MEMCPY(BUFFER(ibuf), BUFFER(msgbuf), 8); 412 DES_XFORM(UBUFFER(msgbuf)); 413 for (c = 0; c < 8; c++) 414 UCHAR(msgbuf, c) ^= UCHAR(ivec, c); 415 MEMCPY(BUFFER(ivec), BUFFER(ibuf), 8); 416 /* 417 * if the last one, handle it specially 418 */ 419 if ((c = fgetc(fp)) == EOF) { 420 n = CHAR(msgbuf, 7); 421 if (n < 0 || n > 7) { 422 err("decryption failed (block corrupted)"); 423 return EOF; 424 } 425 } else 426 (void)ungetc(c, fp); 427 return n; 428 } 429 if (n > 0) 430 err("decryption failed (incomplete block)"); 431 else if (n < 0) 432 err("cannot read file"); 433 return EOF; 434 } 435 #endif /* DES */ 436