cbc.c revision 50471
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#if 0 42static char * const rcsid = "@(#)cbc.c,v 1.2 1994/02/01 00:34:36 alm Exp"; 43#else 44static char * const rcsid = 45 "$FreeBSD: head/bin/ed/cbc.c 50471 1999-08-27 23:15:48Z peter $"; 46#endif 47#endif /* not lint */ 48 49#include <sys/types.h> 50#include <errno.h> 51#include <pwd.h> 52#ifdef DES 53#include <time.h> 54#endif 55 56#include "ed.h" 57 58 59/* 60 * Define a divisor for rand() that yields a uniform distribution in the 61 * range 0-255. 62 */ 63#define RAND_DIV (((unsigned) RAND_MAX + 1) >> 8) 64 65/* 66 * BSD and System V systems offer special library calls that do 67 * block move_liness and fills, so if possible we take advantage of them 68 */ 69#define MEMCPY(dest,src,len) memcpy((dest),(src),(len)) 70#define MEMZERO(dest,len) memset((dest), 0, (len)) 71 72/* Hide the calls to the primitive encryption routines. */ 73#define DES_KEY(buf) \ 74 if (des_setkey(buf)) \ 75 des_error("des_setkey"); 76#define DES_XFORM(buf) \ 77 if (des_cipher(buf, buf, 0L, (inverse ? -1 : 1))) \ 78 des_error("des_cipher"); 79 80/* 81 * read/write - no error checking 82 */ 83#define READ(buf, n, fp) fread(buf, sizeof(char), n, fp) 84#define WRITE(buf, n, fp) fwrite(buf, sizeof(char), n, fp) 85 86/* 87 * some things to make references easier 88 */ 89typedef char Desbuf[8]; 90#define CHAR(x,i) (x[i]) 91#define UCHAR(x,i) (x[i]) 92#define BUFFER(x) (x) 93#define UBUFFER(x) (x) 94 95/* 96 * global variables and related macros 97 */ 98 99enum { /* encrypt, decrypt, authenticate */ 100 MODE_ENCRYPT, MODE_DECRYPT, MODE_AUTHENTICATE 101} mode = MODE_ENCRYPT; 102 103Desbuf ivec; /* initialization vector */ 104Desbuf pvec; /* padding vector */ 105char bits[] = { /* used to extract bits from a char */ 106 '\200', '\100', '\040', '\020', '\010', '\004', '\002', '\001' 107}; 108int pflag; /* 1 to preserve parity bits */ 109 110unsigned char des_buf[8]; /* shared buffer for get_des_char/put_des_char */ 111int des_ct = 0; /* count for get_des_char/put_des_char */ 112int des_n = 0; /* index for put_des_char/get_des_char */ 113 114 115/* init_des_cipher: initialize DES */ 116void 117init_des_cipher() 118{ 119#ifdef DES 120 int i; 121 122 des_ct = des_n = 0; 123 124 /* initialize the initialization vector */ 125 MEMZERO(ivec, 8); 126 127 /* initialize the padding vector */ 128 srand((unsigned) time((time_t *) 0)); 129 for (i = 0; i < 8; i++) 130 CHAR(pvec, i) = (char) (rand()/RAND_DIV); 131#endif 132} 133 134 135/* get_des_char: return next char in an encrypted file */ 136int 137get_des_char(fp) 138 FILE *fp; 139{ 140#ifdef DES 141 if (des_n >= des_ct) { 142 des_n = 0; 143 des_ct = cbc_decode(des_buf, fp); 144 } 145 return (des_ct > 0) ? des_buf[des_n++] : EOF; 146#else 147 return (getc(fp)); 148#endif 149} 150 151 152/* put_des_char: write a char to an encrypted file; return char written */ 153int 154put_des_char(c, fp) 155 int c; 156 FILE *fp; 157{ 158#ifdef DES 159 if (des_n == sizeof des_buf) { 160 des_ct = cbc_encode(des_buf, des_n, fp); 161 des_n = 0; 162 } 163 return (des_ct >= 0) ? (des_buf[des_n++] = c) : EOF; 164#else 165 return (fputc(c, fp)); 166#endif 167} 168 169 170/* flush_des_file: flush an encrypted file's output; return status */ 171int 172flush_des_file(fp) 173 FILE *fp; 174{ 175#ifdef DES 176 if (des_n == sizeof des_buf) { 177 des_ct = cbc_encode(des_buf, des_n, fp); 178 des_n = 0; 179 } 180 return (des_ct >= 0 && cbc_encode(des_buf, des_n, fp) >= 0) ? 0 : EOF; 181#else 182 return (fflush(fp)); 183#endif 184} 185 186#ifdef DES 187/* 188 * get keyword from tty or stdin 189 */ 190int 191get_keyword() 192{ 193 register char *p; /* used to obtain the key */ 194 Desbuf msgbuf; /* I/O buffer */ 195 196 /* 197 * get the key 198 */ 199 if (*(p = getpass("Enter key: "))) { 200 201 /* 202 * copy it, nul-padded, into the key area 203 */ 204 expand_des_key(BUFFER(msgbuf), p); 205 MEMZERO(p, _PASSWORD_LEN); 206 set_des_key(msgbuf); 207 MEMZERO(msgbuf, sizeof msgbuf); 208 return 1; 209 } 210 return 0; 211} 212 213 214/* 215 * print a warning message and, possibly, terminate 216 */ 217void 218des_error(s) 219 char *s; /* the message */ 220{ 221 (void)sprintf(errmsg, "%s", s ? s : strerror(errno)); 222} 223 224/* 225 * map a hex character to an integer 226 */ 227int 228hex_to_binary(c, radix) 229 int c; /* char to be converted */ 230 int radix; /* base (2 to 16) */ 231{ 232 switch(c) { 233 case '0': return(0x0); 234 case '1': return(0x1); 235 case '2': return(radix > 2 ? 0x2 : -1); 236 case '3': return(radix > 3 ? 0x3 : -1); 237 case '4': return(radix > 4 ? 0x4 : -1); 238 case '5': return(radix > 5 ? 0x5 : -1); 239 case '6': return(radix > 6 ? 0x6 : -1); 240 case '7': return(radix > 7 ? 0x7 : -1); 241 case '8': return(radix > 8 ? 0x8 : -1); 242 case '9': return(radix > 9 ? 0x9 : -1); 243 case 'A': case 'a': return(radix > 10 ? 0xa : -1); 244 case 'B': case 'b': return(radix > 11 ? 0xb : -1); 245 case 'C': case 'c': return(radix > 12 ? 0xc : -1); 246 case 'D': case 'd': return(radix > 13 ? 0xd : -1); 247 case 'E': case 'e': return(radix > 14 ? 0xe : -1); 248 case 'F': case 'f': return(radix > 15 ? 0xf : -1); 249 } 250 /* 251 * invalid character 252 */ 253 return(-1); 254} 255 256/* 257 * convert the key to a bit pattern 258 */ 259void 260expand_des_key(obuf, ibuf) 261 char *obuf; /* bit pattern */ 262 char *ibuf; /* the key itself */ 263{ 264 register int i, j; /* counter in a for loop */ 265 int nbuf[64]; /* used for hex/key translation */ 266 267 /* 268 * leading '0x' or '0X' == hex key 269 */ 270 if (ibuf[0] == '0' && (ibuf[1] == 'x' || ibuf[1] == 'X')) { 271 ibuf = &ibuf[2]; 272 /* 273 * now translate it, bombing on any illegal hex digit 274 */ 275 for (i = 0; ibuf[i] && i < 16; i++) 276 if ((nbuf[i] = hex_to_binary((int) ibuf[i], 16)) == -1) 277 des_error("bad hex digit in key"); 278 while (i < 16) 279 nbuf[i++] = 0; 280 for (i = 0; i < 8; i++) 281 obuf[i] = 282 ((nbuf[2*i]&0xf)<<4) | (nbuf[2*i+1]&0xf); 283 /* preserve parity bits */ 284 pflag = 1; 285 return; 286 } 287 /* 288 * leading '0b' or '0B' == binary key 289 */ 290 if (ibuf[0] == '0' && (ibuf[1] == 'b' || ibuf[1] == 'B')) { 291 ibuf = &ibuf[2]; 292 /* 293 * now translate it, bombing on any illegal binary digit 294 */ 295 for (i = 0; ibuf[i] && i < 16; i++) 296 if ((nbuf[i] = hex_to_binary((int) ibuf[i], 2)) == -1) 297 des_error("bad binary digit in key"); 298 while (i < 64) 299 nbuf[i++] = 0; 300 for (i = 0; i < 8; i++) 301 for (j = 0; j < 8; j++) 302 obuf[i] = (obuf[i]<<1)|nbuf[8*i+j]; 303 /* preserve parity bits */ 304 pflag = 1; 305 return; 306 } 307 /* 308 * no special leader -- ASCII 309 */ 310 (void)strncpy(obuf, ibuf, 8); 311} 312 313/***************** 314 * DES FUNCTIONS * 315 *****************/ 316/* 317 * This sets the DES key and (if you're using the deszip version) 318 * the direction of the transformation. This uses the Sun 319 * to map the 64-bit key onto the 56 bits that the key schedule 320 * generation routines use: the old way, which just uses the user- 321 * supplied 64 bits as is, and the new way, which resets the parity 322 * bit to be the same as the low-order bit in each character. The 323 * new way generates a greater variety of key schedules, since many 324 * systems set the parity (high) bit of each character to 0, and the 325 * DES ignores the low order bit of each character. 326 */ 327void 328set_des_key(buf) 329 Desbuf buf; /* key block */ 330{ 331 register int i, j; /* counter in a for loop */ 332 register int par; /* parity counter */ 333 334 /* 335 * if the parity is not preserved, flip it 336 */ 337 if (!pflag) { 338 for (i = 0; i < 8; i++) { 339 par = 0; 340 for (j = 1; j < 8; j++) 341 if ((bits[j]&UCHAR(buf, i)) != 0) 342 par++; 343 if ((par&01) == 01) 344 UCHAR(buf, i) = UCHAR(buf, i)&0177; 345 else 346 UCHAR(buf, i) = (UCHAR(buf, i)&0177)|0200; 347 } 348 } 349 350 DES_KEY(UBUFFER(buf)); 351} 352 353 354/* 355 * This encrypts using the Cipher Block Chaining mode of DES 356 */ 357int 358cbc_encode(msgbuf, n, fp) 359 char *msgbuf; 360 int n; 361 FILE *fp; 362{ 363 int inverse = 0; /* 0 to encrypt, 1 to decrypt */ 364 365 /* 366 * do the transformation 367 */ 368 if (n == 8) { 369 for (n = 0; n < 8; n++) 370 CHAR(msgbuf, n) ^= CHAR(ivec, n); 371 DES_XFORM(UBUFFER(msgbuf)); 372 MEMCPY(BUFFER(ivec), BUFFER(msgbuf), 8); 373 return WRITE(BUFFER(msgbuf), 8, fp); 374 } 375 /* 376 * at EOF or last block -- in either case, the last byte contains 377 * the character representation of the number of bytes in it 378 */ 379/* 380 MEMZERO(msgbuf + n, 8 - n); 381*/ 382 /* 383 * Pad the last block randomly 384 */ 385 (void)MEMCPY(BUFFER(msgbuf + n), BUFFER(pvec), 8 - n); 386 CHAR(msgbuf, 7) = n; 387 for (n = 0; n < 8; n++) 388 CHAR(msgbuf, n) ^= CHAR(ivec, n); 389 DES_XFORM(UBUFFER(msgbuf)); 390 return WRITE(BUFFER(msgbuf), 8, fp); 391} 392 393/* 394 * This decrypts using the Cipher Block Chaining mode of DES 395 */ 396int 397cbc_decode(msgbuf, fp) 398 char *msgbuf; /* I/O buffer */ 399 FILE *fp; /* input file descriptor */ 400{ 401 Desbuf ibuf; /* temp buffer for initialization vector */ 402 register int n; /* number of bytes actually read */ 403 register int c; /* used to test for EOF */ 404 int inverse = 1; /* 0 to encrypt, 1 to decrypt */ 405 406 if ((n = READ(BUFFER(msgbuf), 8, fp)) == 8) { 407 /* 408 * do the transformation 409 */ 410 MEMCPY(BUFFER(ibuf), BUFFER(msgbuf), 8); 411 DES_XFORM(UBUFFER(msgbuf)); 412 for (c = 0; c < 8; c++) 413 UCHAR(msgbuf, c) ^= UCHAR(ivec, c); 414 MEMCPY(BUFFER(ivec), BUFFER(ibuf), 8); 415 /* 416 * if the last one, handle it specially 417 */ 418 if ((c = fgetc(fp)) == EOF) { 419 n = CHAR(msgbuf, 7); 420 if (n < 0 || n > 7) { 421 des_error("decryption failed (block corrupted)"); 422 return EOF; 423 } 424 } else 425 (void)ungetc(c, fp); 426 return n; 427 } 428 if (n > 0) 429 des_error("decryption failed (incomplete block)"); 430 else if (n < 0) 431 des_error("cannot read file"); 432 return EOF; 433} 434#endif /* DES */ 435