cbc.c revision 115717
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 115717 2003-06-02 19:06:28Z markm $"); 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 79DES_cblock ivec; /* initialization vector */ 80DES_cblock pvec; /* padding vector */ 81 82char bits[] = { /* used to extract bits from a char */ 83 '\200', '\100', '\040', '\020', '\010', '\004', '\002', '\001' 84}; 85 86int pflag; /* 1 to preserve parity bits */ 87 88DES_key_schedule schedule; /* expanded DES key */ 89 90unsigned char des_buf[8]; /* shared buffer for get_des_char/put_des_char */ 91int des_ct = 0; /* count for get_des_char/put_des_char */ 92int des_n = 0; /* index for put_des_char/get_des_char */ 93 94/* init_des_cipher: initialize DES */ 95void 96init_des_cipher(void) 97{ 98#ifdef DES 99 int i; 100 101 des_ct = des_n = 0; 102 103 /* initialize the initialization vector */ 104 MEMZERO(ivec, 8); 105 106 /* initialize the padding vector */ 107 for (i = 0; i < 8; i++) 108 pvec[i] = (char) (arc4random() % 256); 109#endif 110} 111 112 113/* get_des_char: return next char in an encrypted file */ 114int 115get_des_char(FILE *fp) 116{ 117#ifdef DES 118 if (des_n >= des_ct) { 119 des_n = 0; 120 des_ct = cbc_decode(des_buf, fp); 121 } 122 return (des_ct > 0) ? des_buf[des_n++] : EOF; 123#else 124 return (getc(fp)); 125#endif 126} 127 128 129/* put_des_char: write a char to an encrypted file; return char written */ 130int 131put_des_char(int c, FILE *fp) 132{ 133#ifdef DES 134 if (des_n == sizeof des_buf) { 135 des_ct = cbc_encode(des_buf, des_n, fp); 136 des_n = 0; 137 } 138 return (des_ct >= 0) ? (des_buf[des_n++] = c) : EOF; 139#else 140 return (fputc(c, fp)); 141#endif 142} 143 144 145/* flush_des_file: flush an encrypted file's output; return status */ 146int 147flush_des_file(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 && cbc_encode(des_buf, des_n, fp) >= 0) ? 0 : EOF; 155#else 156 return (fflush(fp)); 157#endif 158} 159 160#ifdef DES 161/* 162 * get keyword from tty or stdin 163 */ 164int 165get_keyword(void) 166{ 167 char *p; /* used to obtain the key */ 168 DES_cblock msgbuf; /* I/O buffer */ 169 170 /* 171 * get the key 172 */ 173 if (*(p = getpass("Enter key: "))) { 174 175 /* 176 * copy it, nul-padded, into the key area 177 */ 178 expand_des_key(msgbuf, p); 179 MEMZERO(p, _PASSWORD_LEN); 180 set_des_key(&msgbuf); 181 MEMZERO(msgbuf, sizeof msgbuf); 182 return 1; 183 } 184 return 0; 185} 186 187 188/* 189 * print a warning message and, possibly, terminate 190 */ 191void 192des_error(const char *s) 193{ 194 errmsg = s ? s : strerror(errno); 195} 196 197/* 198 * map a hex character to an integer 199 */ 200int 201hex_to_binary(int c, int radix) 202{ 203 switch(c) { 204 case '0': return(0x0); 205 case '1': return(0x1); 206 case '2': return(radix > 2 ? 0x2 : -1); 207 case '3': return(radix > 3 ? 0x3 : -1); 208 case '4': return(radix > 4 ? 0x4 : -1); 209 case '5': return(radix > 5 ? 0x5 : -1); 210 case '6': return(radix > 6 ? 0x6 : -1); 211 case '7': return(radix > 7 ? 0x7 : -1); 212 case '8': return(radix > 8 ? 0x8 : -1); 213 case '9': return(radix > 9 ? 0x9 : -1); 214 case 'A': case 'a': return(radix > 10 ? 0xa : -1); 215 case 'B': case 'b': return(radix > 11 ? 0xb : -1); 216 case 'C': case 'c': return(radix > 12 ? 0xc : -1); 217 case 'D': case 'd': return(radix > 13 ? 0xd : -1); 218 case 'E': case 'e': return(radix > 14 ? 0xe : -1); 219 case 'F': case 'f': return(radix > 15 ? 0xf : -1); 220 } 221 /* 222 * invalid character 223 */ 224 return(-1); 225} 226 227/* 228 * convert the key to a bit pattern 229 * obuf bit pattern 230 * kbuf the key itself 231 */ 232void 233expand_des_key(char *obuf, char *kbuf) 234{ 235 int i, j; /* counter in a for loop */ 236 int nbuf[64]; /* used for hex/key translation */ 237 238 /* 239 * leading '0x' or '0X' == hex key 240 */ 241 if (kbuf[0] == '0' && (kbuf[1] == 'x' || kbuf[1] == 'X')) { 242 kbuf = &kbuf[2]; 243 /* 244 * now translate it, bombing on any illegal hex digit 245 */ 246 for (i = 0; kbuf[i] && i < 16; i++) 247 if ((nbuf[i] = hex_to_binary((int) kbuf[i], 16)) == -1) 248 des_error("bad hex digit in key"); 249 while (i < 16) 250 nbuf[i++] = 0; 251 for (i = 0; i < 8; i++) 252 obuf[i] = 253 ((nbuf[2*i]&0xf)<<4) | (nbuf[2*i+1]&0xf); 254 /* preserve parity bits */ 255 pflag = 1; 256 return; 257 } 258 /* 259 * leading '0b' or '0B' == binary key 260 */ 261 if (kbuf[0] == '0' && (kbuf[1] == 'b' || kbuf[1] == 'B')) { 262 kbuf = &kbuf[2]; 263 /* 264 * now translate it, bombing on any illegal binary digit 265 */ 266 for (i = 0; kbuf[i] && i < 16; i++) 267 if ((nbuf[i] = hex_to_binary((int) kbuf[i], 2)) == -1) 268 des_error("bad binary digit in key"); 269 while (i < 64) 270 nbuf[i++] = 0; 271 for (i = 0; i < 8; i++) 272 for (j = 0; j < 8; j++) 273 obuf[i] = (obuf[i]<<1)|nbuf[8*i+j]; 274 /* preserve parity bits */ 275 pflag = 1; 276 return; 277 } 278 /* 279 * no special leader -- ASCII 280 */ 281 (void)strncpy(obuf, kbuf, 8); 282} 283 284/***************** 285 * DES FUNCTIONS * 286 *****************/ 287/* 288 * This sets the DES key and (if you're using the deszip version) 289 * the direction of the transformation. This uses the Sun 290 * to map the 64-bit key onto the 56 bits that the key schedule 291 * generation routines use: the old way, which just uses the user- 292 * supplied 64 bits as is, and the new way, which resets the parity 293 * bit to be the same as the low-order bit in each character. The 294 * new way generates a greater variety of key schedules, since many 295 * systems set the parity (high) bit of each character to 0, and the 296 * DES ignores the low order bit of each character. 297 */ 298void 299set_des_key(DES_cblock *buf) /* key block */ 300{ 301 int i, j; /* counter in a for loop */ 302 int par; /* parity counter */ 303 304 /* 305 * if the parity is not preserved, flip it 306 */ 307 if (!pflag) { 308 for (i = 0; i < 8; i++) { 309 par = 0; 310 for (j = 1; j < 8; j++) 311 if ((bits[j] & (*buf)[i]) != 0) 312 par++; 313 if ((par & 0x01) == 0x01) 314 (*buf)[i] &= 0x7f; 315 else 316 (*buf)[i] = ((*buf)[i] & 0x7f) | 0x80; 317 } 318 } 319 320 DES_set_odd_parity(buf); 321 DES_set_key(buf, &schedule); 322} 323 324 325/* 326 * This encrypts using the Cipher Block Chaining mode of DES 327 */ 328int 329cbc_encode(unsigned char *msgbuf, int n, FILE *fp) 330{ 331 int inverse = 0; /* 0 to encrypt, 1 to decrypt */ 332 333 /* 334 * do the transformation 335 */ 336 if (n == 8) { 337 for (n = 0; n < 8; n++) 338 msgbuf[n] ^= ivec[n]; 339 DES_XFORM((DES_cblock *)msgbuf); 340 MEMCPY(ivec, msgbuf, 8); 341 return WRITE(msgbuf, 8, fp); 342 } 343 /* 344 * at EOF or last block -- in either case, the last byte contains 345 * the character representation of the number of bytes in it 346 */ 347/* 348 MEMZERO(msgbuf + n, 8 - n); 349*/ 350 /* 351 * Pad the last block randomly 352 */ 353 (void)MEMCPY(msgbuf + n, pvec, 8 - n); 354 msgbuf[7] = n; 355 for (n = 0; n < 8; n++) 356 msgbuf[n] ^= ivec[n]; 357 DES_XFORM((DES_cblock *)msgbuf); 358 return WRITE(msgbuf, 8, fp); 359} 360 361/* 362 * This decrypts using the Cipher Block Chaining mode of DES 363 * msgbuf I/O buffer 364 * fp input file descriptor 365 */ 366int 367cbc_decode(unsigned char *msgbuf, FILE *fp) 368{ 369 DES_cblock tbuf; /* temp buffer for initialization vector */ 370 int n; /* number of bytes actually read */ 371 int c; /* used to test for EOF */ 372 int inverse = 1; /* 0 to encrypt, 1 to decrypt */ 373 374 if ((n = READ(msgbuf, 8, fp)) == 8) { 375 /* 376 * do the transformation 377 */ 378 MEMCPY(tbuf, msgbuf, 8); 379 DES_XFORM((DES_cblock *)msgbuf); 380 for (c = 0; c < 8; c++) 381 msgbuf[c] ^= ivec[c]; 382 MEMCPY(ivec, tbuf, 8); 383 /* 384 * if the last one, handle it specially 385 */ 386 if ((c = fgetc(fp)) == EOF) { 387 n = msgbuf[7]; 388 if (n < 0 || n > 7) { 389 des_error("decryption failed (block corrupted)"); 390 return EOF; 391 } 392 } else 393 (void)ungetc(c, fp); 394 return n; 395 } 396 if (n > 0) 397 des_error("decryption failed (incomplete block)"); 398 else if (n < 0) 399 des_error("cannot read file"); 400 return EOF; 401} 402#endif /* DES */ 403