cbc.c revision 1057
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 41static char *rcsid = "@(#)$Id: cbc.c,v 1.3 1993/12/14 18:01:10 alm Exp $"; 42#endif /* not lint */ 43 44#include <sys/types.h> 45#include <ctype.h> 46#include <errno.h> 47#include <pwd.h> 48 49#include "ed.h" 50 51 52/* 53 * Define a divisor for rand() that yields a uniform distribution in the 54 * range 0-255. 55 */ 56#define RAND_DIV (((unsigned) RAND_MAX + 1) >> 8) 57 58/* 59 * BSD and System V systems offer special library calls that do 60 * block move_liness and fills, so if possible we take advantage of them 61 */ 62#define MEMCPY(dest,src,len) memcpy((dest),(src),(len)) 63#define MEMZERO(dest,len) memset((dest), 0, (len)) 64 65/* Hide the calls to the primitive encryption routines. */ 66#define DES_KEY(buf) \ 67 if (des_setkey(buf)) \ 68 des_error("des_setkey"); 69#define DES_XFORM(buf) \ 70 if (des_cipher(buf, buf, 0L, (inverse ? -1 : 1))) \ 71 des_error("des_cipher"); 72 73/* 74 * read/write - no error checking 75 */ 76#define READ(buf, n, fp) fread(buf, sizeof(char), n, fp) 77#define WRITE(buf, n, fp) fwrite(buf, sizeof(char), n, fp) 78 79/* 80 * some things to make references easier 81 */ 82typedef char Desbuf[8]; 83#define CHAR(x,i) (x[i]) 84#define UCHAR(x,i) (x[i]) 85#define BUFFER(x) (x) 86#define UBUFFER(x) (x) 87 88/* 89 * global variables and related macros 90 */ 91 92enum { /* encrypt, decrypt, authenticate */ 93 MODE_ENCRYPT, MODE_DECRYPT, MODE_AUTHENTICATE 94} mode = MODE_ENCRYPT; 95 96Desbuf ivec; /* initialization vector */ 97Desbuf pvec; /* padding vector */ 98char bits[] = { /* used to extract bits from a char */ 99 '\200', '\100', '\040', '\020', '\010', '\004', '\002', '\001' 100}; 101int pflag; /* 1 to preserve parity bits */ 102 103unsigned char des_buf[8]; /* shared buffer for get_des_char/put_des_char */ 104int des_ct = 0; /* count for get_des_char/put_des_char */ 105int des_n = 0; /* index for put_des_char/get_des_char */ 106 107 108/* init_des_cipher: initialize DES */ 109void 110init_des_cipher() 111{ 112#ifdef DES 113 int i; 114 115 des_ct = des_n = 0; 116 117 /* initialize the initialization vctor */ 118 MEMZERO(ivec, 8); 119 120 /* intialize the padding vector */ 121 srand((unsigned) time((time_t *) 0)); 122 for (i = 0; i < 8; i++) 123 CHAR(pvec, i) = (char) (rand()/RAND_DIV); 124#endif 125} 126 127 128/* get_des_char: return next char in an encrypted file */ 129int 130get_des_char(fp) 131 FILE *fp; 132{ 133#ifdef DES 134 if (des_n >= des_ct) { 135 des_n = 0; 136 des_ct = cbc_decode(des_buf, fp); 137 } 138 return (des_ct > 0) ? des_buf[des_n++] : EOF; 139#endif 140} 141 142 143/* put_des_char: write a char to an encrypted file; return char written */ 144int 145put_des_char(c, fp) 146 int c; 147 FILE *fp; 148{ 149#ifdef DES 150 if (des_n == sizeof des_buf) { 151 des_ct = cbc_encode(des_buf, des_n, fp); 152 des_n = 0; 153 } 154 return (des_ct >= 0) ? (des_buf[des_n++] = c) : EOF; 155#endif 156} 157 158 159/* flush_des_file: flush an encrypted file's output; return status */ 160int 161flush_des_file(fp) 162 FILE *fp; 163{ 164#ifdef DES 165 if (des_n == sizeof des_buf) { 166 des_ct = cbc_encode(des_buf, des_n, fp); 167 des_n = 0; 168 } 169 return (des_ct >= 0 && cbc_encode(des_buf, des_n, fp) >= 0) ? 0 : EOF; 170#endif 171} 172 173#ifdef DES 174/* 175 * get keyword from tty or stdin 176 */ 177int 178get_keyword() 179{ 180 register char *p; /* used to obtain the key */ 181 Desbuf msgbuf; /* I/O buffer */ 182 183 /* 184 * get the key 185 */ 186 if (*(p = getpass("Enter key: "))) { 187 188 /* 189 * copy it, nul-padded, into the key area 190 */ 191 expand_des_key(BUFFER(msgbuf), p); 192 MEMZERO(p, _PASSWORD_LEN); 193 set_des_key(msgbuf); 194 MEMZERO(msgbuf, sizeof msgbuf); 195 return 1; 196 } 197 return 0; 198} 199 200 201/* 202 * print a warning message and, possibly, terminate 203 */ 204void 205des_error(s) 206 char *s; /* the message */ 207{ 208 (void)sprintf(errmsg, "%s", s ? s : strerror(errno)); 209} 210 211/* 212 * map a hex character to an integer 213 */ 214int 215hex_to_binary(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 */ 246void 247expand_des_key(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] = hex_to_binary((int) ibuf[i], 16)) == -1) 264 des_error("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] = hex_to_binary((int) ibuf[i], 2)) == -1) 284 des_error("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 */ 314void 315set_des_key(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 */ 344int 345cbc_encode(msgbuf, n, fp) 346 char *msgbuf; 347 int n; 348 FILE *fp; 349{ 350 int inverse = 0; /* 0 to encrypt, 1 to decrypt */ 351 352 /* 353 * do the transformation 354 */ 355 if (n == 8) { 356 for (n = 0; n < 8; n++) 357 CHAR(msgbuf, n) ^= CHAR(ivec, n); 358 DES_XFORM(UBUFFER(msgbuf)); 359 MEMCPY(BUFFER(ivec), BUFFER(msgbuf), 8); 360 return WRITE(BUFFER(msgbuf), 8, fp); 361 } 362 /* 363 * at EOF or last block -- in either case, the last byte contains 364 * the character representation of the number of bytes in it 365 */ 366/* 367 MEMZERO(msgbuf + n, 8 - n); 368*/ 369 /* 370 * Pad the last block randomly 371 */ 372 (void)MEMCPY(BUFFER(msgbuf + n), BUFFER(pvec), 8 - n); 373 CHAR(msgbuf, 7) = n; 374 for (n = 0; n < 8; n++) 375 CHAR(msgbuf, n) ^= CHAR(ivec, n); 376 DES_XFORM(UBUFFER(msgbuf)); 377 return WRITE(BUFFER(msgbuf), 8, fp); 378} 379 380/* 381 * This decrypts using the Cipher Block Chaining mode of DES 382 */ 383int 384cbc_decode(msgbuf, fp) 385 char *msgbuf; /* I/O buffer */ 386 FILE *fp; /* input file descriptor */ 387{ 388 Desbuf ibuf; /* temp buffer for initialization vector */ 389 register int n; /* number of bytes actually read */ 390 register int c; /* used to test for EOF */ 391 int inverse = 1; /* 0 to encrypt, 1 to decrypt */ 392 393 if ((n = READ(BUFFER(msgbuf), 8, fp)) == 8) { 394 /* 395 * do the transformation 396 */ 397 MEMCPY(BUFFER(ibuf), BUFFER(msgbuf), 8); 398 DES_XFORM(UBUFFER(msgbuf)); 399 for (c = 0; c < 8; c++) 400 UCHAR(msgbuf, c) ^= UCHAR(ivec, c); 401 MEMCPY(BUFFER(ivec), BUFFER(ibuf), 8); 402 /* 403 * if the last one, handle it specially 404 */ 405 if ((c = fgetc(fp)) == EOF) { 406 n = CHAR(msgbuf, 7); 407 if (n < 0 || n > 7) { 408 des_error("decryption failed (block corrupted)"); 409 return EOF; 410 } 411 } else 412 (void)ungetc(c, fp); 413 return n; 414 } 415 if (n > 0) 416 des_error("decryption failed (incomplete block)"); 417 else if (n < 0) 418 des_error("cannot read file"); 419 return EOF; 420} 421#endif /* DES */ 422