cbc.c revision 115777
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 38#include <sys/cdefs.h> 39__FBSDID("$FreeBSD: head/bin/ed/cbc.c 115777 2003-06-03 17:03:48Z jhay $"); 40 41#include <sys/types.h> 42#include <errno.h> 43#include <pwd.h> 44#ifdef DES 45#include <time.h> 46#include <openssl/des.h> 47#define ED_DES_INCLUDES 48#endif 49 50#include "ed.h" 51 52 53/* 54 * BSD and System V systems offer special library calls that do 55 * block move_liness and fills, so if possible we take advantage of them 56 */ 57#define MEMCPY(dest,src,len) memcpy((dest),(src),(len)) 58#define MEMZERO(dest,len) memset((dest), 0, (len)) 59 60/* Hide the calls to the primitive encryption routines. */ 61#define DES_XFORM(buf) \ 62 DES_ecb_encrypt(buf, buf, &schedule, \ 63 inverse ? DES_DECRYPT : DES_ENCRYPT); 64 65/* 66 * read/write - no error checking 67 */ 68#define READ(buf, n, fp) fread(buf, sizeof(char), n, fp) 69#define WRITE(buf, n, fp) fwrite(buf, sizeof(char), n, fp) 70 71/* 72 * global variables and related macros 73 */ 74 75enum { /* encrypt, decrypt, authenticate */ 76 MODE_ENCRYPT, MODE_DECRYPT, MODE_AUTHENTICATE 77} mode = MODE_ENCRYPT; 78 79#ifdef DES 80DES_cblock ivec; /* initialization vector */ 81DES_cblock pvec; /* padding vector */ 82#endif 83 84char bits[] = { /* used to extract bits from a char */ 85 '\200', '\100', '\040', '\020', '\010', '\004', '\002', '\001' 86}; 87 88int pflag; /* 1 to preserve parity bits */ 89 90#ifdef DES 91DES_key_schedule schedule; /* expanded DES key */ 92#endif 93 94unsigned char des_buf[8]; /* shared buffer for get_des_char/put_des_char */ 95int des_ct = 0; /* count for get_des_char/put_des_char */ 96int des_n = 0; /* index for put_des_char/get_des_char */ 97 98/* init_des_cipher: initialize DES */ 99void 100init_des_cipher(void) 101{ 102#ifdef DES 103 int i; 104 105 des_ct = des_n = 0; 106 107 /* initialize the initialization vector */ 108 MEMZERO(ivec, 8); 109 110 /* initialize the padding vector */ 111 for (i = 0; i < 8; i++) 112 pvec[i] = (char) (arc4random() % 256); 113#endif 114} 115 116 117/* get_des_char: return next char in an encrypted file */ 118int 119get_des_char(FILE *fp) 120{ 121#ifdef DES 122 if (des_n >= des_ct) { 123 des_n = 0; 124 des_ct = cbc_decode(des_buf, fp); 125 } 126 return (des_ct > 0) ? des_buf[des_n++] : EOF; 127#else 128 return (getc(fp)); 129#endif 130} 131 132 133/* put_des_char: write a char to an encrypted file; return char written */ 134int 135put_des_char(int c, FILE *fp) 136{ 137#ifdef DES 138 if (des_n == sizeof des_buf) { 139 des_ct = cbc_encode(des_buf, des_n, fp); 140 des_n = 0; 141 } 142 return (des_ct >= 0) ? (des_buf[des_n++] = c) : EOF; 143#else 144 return (fputc(c, fp)); 145#endif 146} 147 148 149/* flush_des_file: flush an encrypted file's output; return status */ 150int 151flush_des_file(FILE *fp) 152{ 153#ifdef DES 154 if (des_n == sizeof des_buf) { 155 des_ct = cbc_encode(des_buf, des_n, fp); 156 des_n = 0; 157 } 158 return (des_ct >= 0 && cbc_encode(des_buf, des_n, fp) >= 0) ? 0 : EOF; 159#else 160 return (fflush(fp)); 161#endif 162} 163 164#ifdef DES 165/* 166 * get keyword from tty or stdin 167 */ 168int 169get_keyword(void) 170{ 171 char *p; /* used to obtain the key */ 172 DES_cblock msgbuf; /* I/O buffer */ 173 174 /* 175 * get the key 176 */ 177 if (*(p = getpass("Enter key: "))) { 178 179 /* 180 * copy it, nul-padded, into the key area 181 */ 182 expand_des_key(msgbuf, p); 183 MEMZERO(p, _PASSWORD_LEN); 184 set_des_key(&msgbuf); 185 MEMZERO(msgbuf, sizeof msgbuf); 186 return 1; 187 } 188 return 0; 189} 190 191 192/* 193 * print a warning message and, possibly, terminate 194 */ 195void 196des_error(const char *s) 197{ 198 errmsg = s ? s : strerror(errno); 199} 200 201/* 202 * map a hex character to an integer 203 */ 204int 205hex_to_binary(int c, int radix) 206{ 207 switch(c) { 208 case '0': return(0x0); 209 case '1': return(0x1); 210 case '2': return(radix > 2 ? 0x2 : -1); 211 case '3': return(radix > 3 ? 0x3 : -1); 212 case '4': return(radix > 4 ? 0x4 : -1); 213 case '5': return(radix > 5 ? 0x5 : -1); 214 case '6': return(radix > 6 ? 0x6 : -1); 215 case '7': return(radix > 7 ? 0x7 : -1); 216 case '8': return(radix > 8 ? 0x8 : -1); 217 case '9': return(radix > 9 ? 0x9 : -1); 218 case 'A': case 'a': return(radix > 10 ? 0xa : -1); 219 case 'B': case 'b': return(radix > 11 ? 0xb : -1); 220 case 'C': case 'c': return(radix > 12 ? 0xc : -1); 221 case 'D': case 'd': return(radix > 13 ? 0xd : -1); 222 case 'E': case 'e': return(radix > 14 ? 0xe : -1); 223 case 'F': case 'f': return(radix > 15 ? 0xf : -1); 224 } 225 /* 226 * invalid character 227 */ 228 return(-1); 229} 230 231/* 232 * convert the key to a bit pattern 233 * obuf bit pattern 234 * kbuf the key itself 235 */ 236void 237expand_des_key(char *obuf, char *kbuf) 238{ 239 int i, j; /* counter in a for loop */ 240 int nbuf[64]; /* used for hex/key translation */ 241 242 /* 243 * leading '0x' or '0X' == hex key 244 */ 245 if (kbuf[0] == '0' && (kbuf[1] == 'x' || kbuf[1] == 'X')) { 246 kbuf = &kbuf[2]; 247 /* 248 * now translate it, bombing on any illegal hex digit 249 */ 250 for (i = 0; kbuf[i] && i < 16; i++) 251 if ((nbuf[i] = hex_to_binary((int) kbuf[i], 16)) == -1) 252 des_error("bad hex digit in key"); 253 while (i < 16) 254 nbuf[i++] = 0; 255 for (i = 0; i < 8; i++) 256 obuf[i] = 257 ((nbuf[2*i]&0xf)<<4) | (nbuf[2*i+1]&0xf); 258 /* preserve parity bits */ 259 pflag = 1; 260 return; 261 } 262 /* 263 * leading '0b' or '0B' == binary key 264 */ 265 if (kbuf[0] == '0' && (kbuf[1] == 'b' || kbuf[1] == 'B')) { 266 kbuf = &kbuf[2]; 267 /* 268 * now translate it, bombing on any illegal binary digit 269 */ 270 for (i = 0; kbuf[i] && i < 16; i++) 271 if ((nbuf[i] = hex_to_binary((int) kbuf[i], 2)) == -1) 272 des_error("bad binary digit in key"); 273 while (i < 64) 274 nbuf[i++] = 0; 275 for (i = 0; i < 8; i++) 276 for (j = 0; j < 8; j++) 277 obuf[i] = (obuf[i]<<1)|nbuf[8*i+j]; 278 /* preserve parity bits */ 279 pflag = 1; 280 return; 281 } 282 /* 283 * no special leader -- ASCII 284 */ 285 (void)strncpy(obuf, kbuf, 8); 286} 287 288/***************** 289 * DES FUNCTIONS * 290 *****************/ 291/* 292 * This sets the DES key and (if you're using the deszip version) 293 * the direction of the transformation. This uses the Sun 294 * to map the 64-bit key onto the 56 bits that the key schedule 295 * generation routines use: the old way, which just uses the user- 296 * supplied 64 bits as is, and the new way, which resets the parity 297 * bit to be the same as the low-order bit in each character. The 298 * new way generates a greater variety of key schedules, since many 299 * systems set the parity (high) bit of each character to 0, and the 300 * DES ignores the low order bit of each character. 301 */ 302void 303set_des_key(DES_cblock *buf) /* key block */ 304{ 305 int i, j; /* counter in a for loop */ 306 int par; /* parity counter */ 307 308 /* 309 * if the parity is not preserved, flip it 310 */ 311 if (!pflag) { 312 for (i = 0; i < 8; i++) { 313 par = 0; 314 for (j = 1; j < 8; j++) 315 if ((bits[j] & (*buf)[i]) != 0) 316 par++; 317 if ((par & 0x01) == 0x01) 318 (*buf)[i] &= 0x7f; 319 else 320 (*buf)[i] = ((*buf)[i] & 0x7f) | 0x80; 321 } 322 } 323 324 DES_set_odd_parity(buf); 325 DES_set_key(buf, &schedule); 326} 327 328 329/* 330 * This encrypts using the Cipher Block Chaining mode of DES 331 */ 332int 333cbc_encode(unsigned char *msgbuf, int n, FILE *fp) 334{ 335 int inverse = 0; /* 0 to encrypt, 1 to decrypt */ 336 337 /* 338 * do the transformation 339 */ 340 if (n == 8) { 341 for (n = 0; n < 8; n++) 342 msgbuf[n] ^= ivec[n]; 343 DES_XFORM((DES_cblock *)msgbuf); 344 MEMCPY(ivec, msgbuf, 8); 345 return WRITE(msgbuf, 8, fp); 346 } 347 /* 348 * at EOF or last block -- in either case, the last byte contains 349 * the character representation of the number of bytes in it 350 */ 351/* 352 MEMZERO(msgbuf + n, 8 - n); 353*/ 354 /* 355 * Pad the last block randomly 356 */ 357 (void)MEMCPY(msgbuf + n, pvec, 8 - n); 358 msgbuf[7] = n; 359 for (n = 0; n < 8; n++) 360 msgbuf[n] ^= ivec[n]; 361 DES_XFORM((DES_cblock *)msgbuf); 362 return WRITE(msgbuf, 8, fp); 363} 364 365/* 366 * This decrypts using the Cipher Block Chaining mode of DES 367 * msgbuf I/O buffer 368 * fp input file descriptor 369 */ 370int 371cbc_decode(unsigned char *msgbuf, FILE *fp) 372{ 373 DES_cblock tbuf; /* temp buffer for initialization vector */ 374 int n; /* number of bytes actually read */ 375 int c; /* used to test for EOF */ 376 int inverse = 1; /* 0 to encrypt, 1 to decrypt */ 377 378 if ((n = READ(msgbuf, 8, fp)) == 8) { 379 /* 380 * do the transformation 381 */ 382 MEMCPY(tbuf, msgbuf, 8); 383 DES_XFORM((DES_cblock *)msgbuf); 384 for (c = 0; c < 8; c++) 385 msgbuf[c] ^= ivec[c]; 386 MEMCPY(ivec, tbuf, 8); 387 /* 388 * if the last one, handle it specially 389 */ 390 if ((c = fgetc(fp)) == EOF) { 391 n = msgbuf[7]; 392 if (n < 0 || n > 7) { 393 des_error("decryption failed (block corrupted)"); 394 return EOF; 395 } 396 } else 397 (void)ungetc(c, fp); 398 return n; 399 } 400 if (n > 0) 401 des_error("decryption failed (incomplete block)"); 402 else if (n < 0) 403 des_error("cannot read file"); 404 return EOF; 405} 406#endif /* DES */ 407