cbc.c revision 1.6
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 40 #ifndef lint 41 static char sccsid[] = "@(#)cbc.c 5.5 (Talke Studio) 6/27/91"; 42 #endif /* not lint */ 43 44 #include <errno.h> 45 #include <pwd.h> 46 #include <unistd.h> 47 #include <stdio.h> 48 #include <ctype.h> 49 #include <stdlib.h> 50 #include <string.h> 51 #include <sys/types.h> 52 53 #include "ed.h" 54 55 /* 56 * Define a divisor for rand() that yields a uniform distribution in the 57 * range 0-255. 58 */ 59 #define RAND_DIV (((unsigned) RAND_MAX + 1) >> 8) 60 61 /* 62 * BSD and System V systems offer special library calls that do 63 * block moves and fills, so if possible we take advantage of them 64 */ 65 #define MEMCPY(dest,src,len) memcpy((dest),(src),(len)) 66 #define MEMZERO(dest,len) memset((dest), 0, (len)) 67 68 /* Hide the calls to the primitive encryption routines. */ 69 #define DES_KEY(buf) \ 70 if (des_setkey(buf)) \ 71 err("des_setkey"); 72 #define DES_XFORM(buf) \ 73 if (des_cipher(buf, buf, 0L, (inverse ? -1 : 1))) \ 74 err("des_cipher"); 75 76 /* 77 * read/write - no error checking 78 */ 79 #define READ(buf, n, fp) fread(buf, sizeof(char), n, fp) 80 #define WRITE(buf, n, fp) fwrite(buf, sizeof(char), n, fp) 81 82 /* 83 * some things to make references easier 84 */ 85 typedef char Desbuf[8]; 86 #define CHAR(x,i) (x[i]) 87 #define UCHAR(x,i) (x[i]) 88 #define BUFFER(x) (x) 89 #define UBUFFER(x) (x) 90 91 /* 92 * global variables and related macros 93 */ 94 95 enum { /* encrypt, decrypt, authenticate */ 96 MODE_ENCRYPT, MODE_DECRYPT, MODE_AUTHENTICATE 97 } mode = MODE_ENCRYPT; 98 99 Desbuf ivec; /* initialization vector */ 100 Desbuf pvec; /* padding vector */ 101 char bits[] = { /* used to extract bits from a char */ 102 '\200', '\100', '\040', '\020', '\010', '\004', '\002', '\001' 103 }; 104 int pflag; /* 1 to preserve parity bits */ 105 106 char des_buf[8]; /* shared buffer for desgetc/desputc */ 107 int des_ct = 0; /* count for desgetc/desputc */ 108 int des_n = 0; /* index for desputc/desgetc */ 109 110 111 /* desinit: initialize DES */ 112 void 113 desinit() 114 { 115 #ifdef DES 116 int i; 117 118 des_ct = des_n = 0; 119 120 /* initialize the initialization vctor */ 121 MEMZERO(ivec, 8); 122 123 /* intialize the padding vector */ 124 srand((unsigned) time((time_t *) 0)); 125 for (i = 0; i < 8; i++) 126 CHAR(pvec, i) = (char) (rand()/RAND_DIV); 127 #endif 128 } 129 130 131 /* desgetc: return next char in an encrypted file */ 132 desgetc(fp) 133 FILE *fp; 134 { 135 #ifdef DES 136 if (des_n >= des_ct) { 137 des_n = 0; 138 des_ct = cbcdec(des_buf, fp); 139 } 140 return (des_ct > 0) ? des_buf[des_n++] : EOF; 141 #endif 142 } 143 144 145 /* desputc: write a char to an encrypted file; return char written */ 146 desputc(c, fp) 147 int c; 148 FILE *fp; 149 { 150 #ifdef DES 151 if (des_n == sizeof des_buf) { 152 des_ct = cbcenc(des_buf, des_n, fp); 153 des_n = 0; 154 } 155 return (des_ct >= 0) ? (des_buf[des_n++] = c) : EOF; 156 #endif 157 } 158 159 160 /* desflush: flush an encrypted file's output; return status */ 161 desflush(fp) 162 FILE *fp; 163 { 164 #ifdef DES 165 if (des_n == sizeof des_buf) { 166 des_ct = cbcenc(des_buf, des_n, fp); 167 des_n = 0; 168 } 169 return (des_ct >= 0 && cbcenc(des_buf, des_n, fp) >= 0) ? 0 : EOF; 170 #endif 171 } 172 173 #ifdef DES 174 /* 175 * get keyword from tty or stdin 176 */ 177 getkey() 178 { 179 register char *p; /* used to obtain the key */ 180 Desbuf msgbuf; /* I/O buffer */ 181 182 /* 183 * get the key 184 */ 185 if (*(p = getpass("Enter key: "))) { 186 187 /* 188 * copy it, nul-padded, into the key area 189 */ 190 cvtkey(BUFFER(msgbuf), p); 191 MEMZERO(p, _PASSWORD_LEN); 192 makekey(msgbuf); 193 MEMZERO(msgbuf, sizeof msgbuf); 194 return 1; 195 } 196 return 0; 197 } 198 199 200 extern char errmsg[]; 201 202 /* 203 * print a warning message and, possibly, terminate 204 */ 205 void 206 err(s) 207 char *s; /* the message */ 208 { 209 (void)sprintf(errmsg, "%s", s ? s : strerror(errno)); 210 } 211 212 /* 213 * map a hex character to an integer 214 */ 215 tobinhex(c, radix) 216 int c; /* char to be converted */ 217 int radix; /* base (2 to 16) */ 218 { 219 switch(c) { 220 case '0': return(0x0); 221 case '1': return(0x1); 222 case '2': return(radix > 2 ? 0x2 : -1); 223 case '3': return(radix > 3 ? 0x3 : -1); 224 case '4': return(radix > 4 ? 0x4 : -1); 225 case '5': return(radix > 5 ? 0x5 : -1); 226 case '6': return(radix > 6 ? 0x6 : -1); 227 case '7': return(radix > 7 ? 0x7 : -1); 228 case '8': return(radix > 8 ? 0x8 : -1); 229 case '9': return(radix > 9 ? 0x9 : -1); 230 case 'A': case 'a': return(radix > 10 ? 0xa : -1); 231 case 'B': case 'b': return(radix > 11 ? 0xb : -1); 232 case 'C': case 'c': return(radix > 12 ? 0xc : -1); 233 case 'D': case 'd': return(radix > 13 ? 0xd : -1); 234 case 'E': case 'e': return(radix > 14 ? 0xe : -1); 235 case 'F': case 'f': return(radix > 15 ? 0xf : -1); 236 } 237 /* 238 * invalid character 239 */ 240 return(-1); 241 } 242 243 /* 244 * convert the key to a bit pattern 245 */ 246 void 247 cvtkey(obuf, ibuf) 248 char *obuf; /* bit pattern */ 249 char *ibuf; /* the key itself */ 250 { 251 register int i, j; /* counter in a for loop */ 252 int nbuf[64]; /* used for hex/key translation */ 253 254 /* 255 * leading '0x' or '0X' == hex key 256 */ 257 if (ibuf[0] == '0' && (ibuf[1] == 'x' || ibuf[1] == 'X')) { 258 ibuf = &ibuf[2]; 259 /* 260 * now translate it, bombing on any illegal hex digit 261 */ 262 for (i = 0; ibuf[i] && i < 16; i++) 263 if ((nbuf[i] = tobinhex((int) ibuf[i], 16)) == -1) 264 err("bad hex digit in key"); 265 while (i < 16) 266 nbuf[i++] = 0; 267 for (i = 0; i < 8; i++) 268 obuf[i] = 269 ((nbuf[2*i]&0xf)<<4) | (nbuf[2*i+1]&0xf); 270 /* preserve parity bits */ 271 pflag = 1; 272 return; 273 } 274 /* 275 * leading '0b' or '0B' == binary key 276 */ 277 if (ibuf[0] == '0' && (ibuf[1] == 'b' || ibuf[1] == 'B')) { 278 ibuf = &ibuf[2]; 279 /* 280 * now translate it, bombing on any illegal binary digit 281 */ 282 for (i = 0; ibuf[i] && i < 16; i++) 283 if ((nbuf[i] = tobinhex((int) ibuf[i], 2)) == -1) 284 err("bad binary digit in key"); 285 while (i < 64) 286 nbuf[i++] = 0; 287 for (i = 0; i < 8; i++) 288 for (j = 0; j < 8; j++) 289 obuf[i] = (obuf[i]<<1)|nbuf[8*i+j]; 290 /* preserve parity bits */ 291 pflag = 1; 292 return; 293 } 294 /* 295 * no special leader -- ASCII 296 */ 297 (void)strncpy(obuf, ibuf, 8); 298 } 299 300 /***************** 301 * DES FUNCTIONS * 302 *****************/ 303 /* 304 * This sets the DES key and (if you're using the deszip version) 305 * the direction of the transformation. This uses the Sun 306 * to map the 64-bit key onto the 56 bits that the key schedule 307 * generation routines use: the old way, which just uses the user- 308 * supplied 64 bits as is, and the new way, which resets the parity 309 * bit to be the same as the low-order bit in each character. The 310 * new way generates a greater variety of key schedules, since many 311 * systems set the parity (high) bit of each character to 0, and the 312 * DES ignores the low order bit of each character. 313 */ 314 void 315 makekey(buf) 316 Desbuf buf; /* key block */ 317 { 318 register int i, j; /* counter in a for loop */ 319 register int par; /* parity counter */ 320 321 /* 322 * if the parity is not preserved, flip it 323 */ 324 if (!pflag) { 325 for (i = 0; i < 8; i++) { 326 par = 0; 327 for (j = 1; j < 8; j++) 328 if ((bits[j]&UCHAR(buf, i)) != 0) 329 par++; 330 if ((par&01) == 01) 331 UCHAR(buf, i) = UCHAR(buf, i)&0177; 332 else 333 UCHAR(buf, i) = (UCHAR(buf, i)&0177)|0200; 334 } 335 } 336 337 DES_KEY(UBUFFER(buf)); 338 } 339 340 341 /* 342 * This encrypts using the Cipher Block Chaining mode of DES 343 */ 344 cbcenc(msgbuf, n, fp) 345 char *msgbuf; 346 int n; 347 FILE *fp; 348 { 349 int inverse = 0; /* 0 to encrypt, 1 to decrypt */ 350 351 /* 352 * do the transformation 353 */ 354 if (n == 8) { 355 for (n = 0; n < 8; n++) 356 CHAR(msgbuf, n) ^= CHAR(ivec, n); 357 DES_XFORM(UBUFFER(msgbuf)); 358 MEMCPY(BUFFER(ivec), BUFFER(msgbuf), 8); 359 return WRITE(BUFFER(msgbuf), 8, fp); 360 } 361 /* 362 * at EOF or last block -- in either case, the last byte contains 363 * the character representation of the number of bytes in it 364 */ 365 /* 366 MEMZERO(msgbuf + n, 8 - n); 367 */ 368 /* 369 * Pad the last block randomly 370 */ 371 (void)MEMCPY(BUFFER(msgbuf + n), BUFFER(pvec), 8 - n); 372 CHAR(msgbuf, 7) = n; 373 for (n = 0; n < 8; n++) 374 CHAR(msgbuf, n) ^= CHAR(ivec, n); 375 DES_XFORM(UBUFFER(msgbuf)); 376 return WRITE(BUFFER(msgbuf), 8, fp); 377 } 378 379 /* 380 * This decrypts using the Cipher Block Chaining mode of DES 381 */ 382 cbcdec(msgbuf, fp) 383 char *msgbuf; /* I/O buffer */ 384 FILE *fp; /* input file descriptor */ 385 { 386 Desbuf ibuf; /* temp buffer for initialization vector */ 387 register int n; /* number of bytes actually read */ 388 register int c; /* used to test for EOF */ 389 int inverse = 1; /* 0 to encrypt, 1 to decrypt */ 390 391 if ((n = READ(BUFFER(msgbuf), 8, fp)) == 8) { 392 /* 393 * do the transformation 394 */ 395 MEMCPY(BUFFER(ibuf), BUFFER(msgbuf), 8); 396 DES_XFORM(UBUFFER(msgbuf)); 397 for (c = 0; c < 8; c++) 398 UCHAR(msgbuf, c) ^= UCHAR(ivec, c); 399 MEMCPY(BUFFER(ivec), BUFFER(ibuf), 8); 400 /* 401 * if the last one, handle it specially 402 */ 403 if ((c = fgetc(fp)) == EOF) { 404 n = CHAR(msgbuf, 7); 405 if (n < 0 || n > 7) { 406 err("decryption failed (block corrupted)"); 407 return EOF; 408 } 409 } else 410 (void)ungetc(c, fp); 411 return n; 412 } 413 if (n > 0) 414 err("decryption failed (incomplete block)"); 415 else if (n < 0) 416 err("cannot read file"); 417 return EOF; 418 } 419 #endif /* DES */ 420
Indexes created Wed Oct 22 06:10:02 GMT 2025