cbc.c revision 7165
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 * $Id: cbc.c,v 1.4 1994/09/24 02:55:24 davidg Exp $ 39 */ 40 41#ifndef lint 42static char *rcsid = "@(#)cbc.c,v 1.2 1994/02/01 00:34:36 alm Exp"; 43#endif /* not lint */ 44 45#include <sys/types.h> 46#include <ctype.h> 47#include <errno.h> 48#include <pwd.h> 49 50#include "ed.h" 51 52 53/* 54 * Define a divisor for rand() that yields a uniform distribution in the 55 * range 0-255. 56 */ 57#define RAND_DIV (((unsigned) RAND_MAX + 1) >> 8) 58 59/* 60 * BSD and System V systems offer special library calls that do 61 * block move_liness and fills, so if possible we take advantage of them 62 */ 63#define MEMCPY(dest,src,len) memcpy((dest),(src),(len)) 64#define MEMZERO(dest,len) memset((dest), 0, (len)) 65 66/* Hide the calls to the primitive encryption routines. */ 67#define DES_KEY(buf) \ 68 if (des_setkey(buf)) \ 69 des_error("des_setkey"); 70#define DES_XFORM(buf) \ 71 if (des_cipher(buf, buf, 0L, (inverse ? -1 : 1))) \ 72 des_error("des_cipher"); 73 74/* 75 * read/write - no error checking 76 */ 77#define READ(buf, n, fp) fread(buf, sizeof(char), n, fp) 78#define WRITE(buf, n, fp) fwrite(buf, sizeof(char), n, fp) 79 80/* 81 * some things to make references easier 82 */ 83typedef char Desbuf[8]; 84#define CHAR(x,i) (x[i]) 85#define UCHAR(x,i) (x[i]) 86#define BUFFER(x) (x) 87#define UBUFFER(x) (x) 88 89/* 90 * global variables and related macros 91 */ 92 93enum { /* encrypt, decrypt, authenticate */ 94 MODE_ENCRYPT, MODE_DECRYPT, MODE_AUTHENTICATE 95} mode = MODE_ENCRYPT; 96 97Desbuf ivec; /* initialization vector */ 98Desbuf pvec; /* padding vector */ 99char bits[] = { /* used to extract bits from a char */ 100 '\200', '\100', '\040', '\020', '\010', '\004', '\002', '\001' 101}; 102int pflag; /* 1 to preserve parity bits */ 103 104unsigned char des_buf[8]; /* shared buffer for get_des_char/put_des_char */ 105int des_ct = 0; /* count for get_des_char/put_des_char */ 106int des_n = 0; /* index for put_des_char/get_des_char */ 107 108 109/* init_des_cipher: initialize DES */ 110void 111init_des_cipher() 112{ 113#ifdef DES 114 int i; 115 116 des_ct = des_n = 0; 117 118 /* initialize the initialization vector */ 119 MEMZERO(ivec, 8); 120 121 /* intialize the padding vector */ 122 srand((unsigned) time((time_t *) 0)); 123 for (i = 0; i < 8; i++) 124 CHAR(pvec, i) = (char) (rand()/RAND_DIV); 125#endif 126} 127 128 129/* get_des_char: return next char in an encrypted file */ 130int 131get_des_char(fp) 132 FILE *fp; 133{ 134#ifdef DES 135 if (des_n >= des_ct) { 136 des_n = 0; 137 des_ct = cbc_decode(des_buf, fp); 138 } 139 return (des_ct > 0) ? des_buf[des_n++] : EOF; 140#else 141 return (getc(fp)); 142#endif 143} 144 145 146/* put_des_char: write a char to an encrypted file; return char written */ 147int 148put_des_char(c, fp) 149 int c; 150 FILE *fp; 151{ 152#ifdef DES 153 if (des_n == sizeof des_buf) { 154 des_ct = cbc_encode(des_buf, des_n, fp); 155 des_n = 0; 156 } 157 return (des_ct >= 0) ? (des_buf[des_n++] = c) : EOF; 158#else 159 return (fputc(c, fp)); 160#endif 161} 162 163 164/* flush_des_file: flush an encrypted file's output; return status */ 165int 166flush_des_file(fp) 167 FILE *fp; 168{ 169#ifdef DES 170 if (des_n == sizeof des_buf) { 171 des_ct = cbc_encode(des_buf, des_n, fp); 172 des_n = 0; 173 } 174 return (des_ct >= 0 && cbc_encode(des_buf, des_n, fp) >= 0) ? 0 : EOF; 175#else 176 return (fflush(fp)); 177#endif 178} 179 180#ifdef DES 181/* 182 * get keyword from tty or stdin 183 */ 184int 185get_keyword() 186{ 187 register char *p; /* used to obtain the key */ 188 Desbuf msgbuf; /* I/O buffer */ 189 190 /* 191 * get the key 192 */ 193 if (*(p = getpass("Enter key: "))) { 194 195 /* 196 * copy it, nul-padded, into the key area 197 */ 198 expand_des_key(BUFFER(msgbuf), p); 199 MEMZERO(p, _PASSWORD_LEN); 200 set_des_key(msgbuf); 201 MEMZERO(msgbuf, sizeof msgbuf); 202 return 1; 203 } 204 return 0; 205} 206 207 208/* 209 * print a warning message and, possibly, terminate 210 */ 211void 212des_error(s) 213 char *s; /* the message */ 214{ 215 (void)sprintf(errmsg, "%s", s ? s : strerror(errno)); 216} 217 218/* 219 * map a hex character to an integer 220 */ 221int 222hex_to_binary(c, radix) 223 int c; /* char to be converted */ 224 int radix; /* base (2 to 16) */ 225{ 226 switch(c) { 227 case '0': return(0x0); 228 case '1': return(0x1); 229 case '2': return(radix > 2 ? 0x2 : -1); 230 case '3': return(radix > 3 ? 0x3 : -1); 231 case '4': return(radix > 4 ? 0x4 : -1); 232 case '5': return(radix > 5 ? 0x5 : -1); 233 case '6': return(radix > 6 ? 0x6 : -1); 234 case '7': return(radix > 7 ? 0x7 : -1); 235 case '8': return(radix > 8 ? 0x8 : -1); 236 case '9': return(radix > 9 ? 0x9 : -1); 237 case 'A': case 'a': return(radix > 10 ? 0xa : -1); 238 case 'B': case 'b': return(radix > 11 ? 0xb : -1); 239 case 'C': case 'c': return(radix > 12 ? 0xc : -1); 240 case 'D': case 'd': return(radix > 13 ? 0xd : -1); 241 case 'E': case 'e': return(radix > 14 ? 0xe : -1); 242 case 'F': case 'f': return(radix > 15 ? 0xf : -1); 243 } 244 /* 245 * invalid character 246 */ 247 return(-1); 248} 249 250/* 251 * convert the key to a bit pattern 252 */ 253void 254expand_des_key(obuf, ibuf) 255 char *obuf; /* bit pattern */ 256 char *ibuf; /* the key itself */ 257{ 258 register int i, j; /* counter in a for loop */ 259 int nbuf[64]; /* used for hex/key translation */ 260 261 /* 262 * leading '0x' or '0X' == hex key 263 */ 264 if (ibuf[0] == '0' && (ibuf[1] == 'x' || ibuf[1] == 'X')) { 265 ibuf = &ibuf[2]; 266 /* 267 * now translate it, bombing on any illegal hex digit 268 */ 269 for (i = 0; ibuf[i] && i < 16; i++) 270 if ((nbuf[i] = hex_to_binary((int) ibuf[i], 16)) == -1) 271 des_error("bad hex digit in key"); 272 while (i < 16) 273 nbuf[i++] = 0; 274 for (i = 0; i < 8; i++) 275 obuf[i] = 276 ((nbuf[2*i]&0xf)<<4) | (nbuf[2*i+1]&0xf); 277 /* preserve parity bits */ 278 pflag = 1; 279 return; 280 } 281 /* 282 * leading '0b' or '0B' == binary key 283 */ 284 if (ibuf[0] == '0' && (ibuf[1] == 'b' || ibuf[1] == 'B')) { 285 ibuf = &ibuf[2]; 286 /* 287 * now translate it, bombing on any illegal binary digit 288 */ 289 for (i = 0; ibuf[i] && i < 16; i++) 290 if ((nbuf[i] = hex_to_binary((int) ibuf[i], 2)) == -1) 291 des_error("bad binary digit in key"); 292 while (i < 64) 293 nbuf[i++] = 0; 294 for (i = 0; i < 8; i++) 295 for (j = 0; j < 8; j++) 296 obuf[i] = (obuf[i]<<1)|nbuf[8*i+j]; 297 /* preserve parity bits */ 298 pflag = 1; 299 return; 300 } 301 /* 302 * no special leader -- ASCII 303 */ 304 (void)strncpy(obuf, ibuf, 8); 305} 306 307/***************** 308 * DES FUNCTIONS * 309 *****************/ 310/* 311 * This sets the DES key and (if you're using the deszip version) 312 * the direction of the transformation. This uses the Sun 313 * to map the 64-bit key onto the 56 bits that the key schedule 314 * generation routines use: the old way, which just uses the user- 315 * supplied 64 bits as is, and the new way, which resets the parity 316 * bit to be the same as the low-order bit in each character. The 317 * new way generates a greater variety of key schedules, since many 318 * systems set the parity (high) bit of each character to 0, and the 319 * DES ignores the low order bit of each character. 320 */ 321void 322set_des_key(buf) 323 Desbuf buf; /* key block */ 324{ 325 register int i, j; /* counter in a for loop */ 326 register int par; /* parity counter */ 327 328 /* 329 * if the parity is not preserved, flip it 330 */ 331 if (!pflag) { 332 for (i = 0; i < 8; i++) { 333 par = 0; 334 for (j = 1; j < 8; j++) 335 if ((bits[j]&UCHAR(buf, i)) != 0) 336 par++; 337 if ((par&01) == 01) 338 UCHAR(buf, i) = UCHAR(buf, i)&0177; 339 else 340 UCHAR(buf, i) = (UCHAR(buf, i)&0177)|0200; 341 } 342 } 343 344 DES_KEY(UBUFFER(buf)); 345} 346 347 348/* 349 * This encrypts using the Cipher Block Chaining mode of DES 350 */ 351int 352cbc_encode(msgbuf, n, fp) 353 char *msgbuf; 354 int n; 355 FILE *fp; 356{ 357 int inverse = 0; /* 0 to encrypt, 1 to decrypt */ 358 359 /* 360 * do the transformation 361 */ 362 if (n == 8) { 363 for (n = 0; n < 8; n++) 364 CHAR(msgbuf, n) ^= CHAR(ivec, n); 365 DES_XFORM(UBUFFER(msgbuf)); 366 MEMCPY(BUFFER(ivec), BUFFER(msgbuf), 8); 367 return WRITE(BUFFER(msgbuf), 8, fp); 368 } 369 /* 370 * at EOF or last block -- in either case, the last byte contains 371 * the character representation of the number of bytes in it 372 */ 373/* 374 MEMZERO(msgbuf + n, 8 - n); 375*/ 376 /* 377 * Pad the last block randomly 378 */ 379 (void)MEMCPY(BUFFER(msgbuf + n), BUFFER(pvec), 8 - n); 380 CHAR(msgbuf, 7) = n; 381 for (n = 0; n < 8; n++) 382 CHAR(msgbuf, n) ^= CHAR(ivec, n); 383 DES_XFORM(UBUFFER(msgbuf)); 384 return WRITE(BUFFER(msgbuf), 8, fp); 385} 386 387/* 388 * This decrypts using the Cipher Block Chaining mode of DES 389 */ 390int 391cbc_decode(msgbuf, fp) 392 char *msgbuf; /* I/O buffer */ 393 FILE *fp; /* input file descriptor */ 394{ 395 Desbuf ibuf; /* temp buffer for initialization vector */ 396 register int n; /* number of bytes actually read */ 397 register int c; /* used to test for EOF */ 398 int inverse = 1; /* 0 to encrypt, 1 to decrypt */ 399 400 if ((n = READ(BUFFER(msgbuf), 8, fp)) == 8) { 401 /* 402 * do the transformation 403 */ 404 MEMCPY(BUFFER(ibuf), BUFFER(msgbuf), 8); 405 DES_XFORM(UBUFFER(msgbuf)); 406 for (c = 0; c < 8; c++) 407 UCHAR(msgbuf, c) ^= UCHAR(ivec, c); 408 MEMCPY(BUFFER(ivec), BUFFER(ibuf), 8); 409 /* 410 * if the last one, handle it specially 411 */ 412 if ((c = fgetc(fp)) == EOF) { 413 n = CHAR(msgbuf, 7); 414 if (n < 0 || n > 7) { 415 des_error("decryption failed (block corrupted)"); 416 return EOF; 417 } 418 } else 419 (void)ungetc(c, fp); 420 return n; 421 } 422 if (n > 0) 423 des_error("decryption failed (incomplete block)"); 424 else if (n < 0) 425 des_error("cannot read file"); 426 return EOF; 427} 428#endif /* DES */ 429