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 * @(#)cbc.c,v 1.2 1994/02/01 00:34:36 alm Exp 40 * $FreeBSD: src/bin/ed/cbc.c,v 1.12.2.1 2001/07/04 22:32:18 kris Exp $ 41 * $DragonFly: src/bin/ed/cbc.c,v 1.7 2004/11/14 19:38:34 joerg Exp $ 42 */ 43 44 #include <sys/types.h> 45 #include <errno.h> 46 #include <pwd.h> 47 #ifdef DES 48 #include <time.h> 49 #endif 50 51 #include "ed.h" 52 53 54 /* 55 * BSD and System V systems offer special library calls that do 56 * block move_liness and fills, so if possible we take advantage of them 57 */ 58 #define MEMCPY(dest,src,len) memcpy((dest),(src),(len)) 59 #define MEMZERO(dest,len) memset((dest), 0, (len)) 60 61 /* Hide the calls to the primitive encryption routines. */ 62 #define DES_KEY(buf) \ 63 if (des_setkey(buf)) \ 64 des_error("des_setkey"); 65 #define DES_XFORM(buf) \ 66 if (des_cipher(buf, buf, 0L, (inverse ? -1 : 1))) \ 67 des_error("des_cipher"); 68 69 /* 70 * read/write - no error checking 71 */ 72 #define READ(buf, n, fp) fread(buf, sizeof(char), n, fp) 73 #define WRITE(buf, n, fp) fwrite(buf, sizeof(char), n, fp) 74 75 /* 76 * some things to make references easier 77 */ 78 typedef char Desbuf[8]; 79 #define CHAR(x,i) (x[i]) 80 #define UCHAR(x,i) (x[i]) 81 #define BUFFER(x) (x) 82 #define UBUFFER(x) (x) 83 84 /* 85 * global variables and related macros 86 */ 87 88 enum { /* encrypt, decrypt, authenticate */ 89 MODE_ENCRYPT, MODE_DECRYPT, MODE_AUTHENTICATE 90 } mode = MODE_ENCRYPT; 91 92 Desbuf ivec; /* initialization vector */ 93 Desbuf pvec; /* padding vector */ 94 char bits[] = { /* used to extract bits from a char */ 95 '\200', '\100', '\040', '\020', '\010', '\004', '\002', '\001' 96 }; 97 int pflag; /* 1 to preserve parity bits */ 98 99 char des_buf[8]; /* shared buffer for get_des_char/put_des_char */ 100 int des_ct = 0; /* count for get_des_char/put_des_char */ 101 int des_n = 0; /* index for put_des_char/get_des_char */ 102 103 104 /* init_des_cipher: initialize DES */ 105 void 106 init_des_cipher(void) 107 { 108 #ifdef DES 109 int i; 110 111 des_ct = des_n = 0; 112 113 /* initialize the initialization vector */ 114 MEMZERO(ivec, 8); 115 116 /* initialize the padding vector */ 117 for (i = 0; i < 8; i++) 118 CHAR(pvec, i) = (char) (arc4random() % 256); 119 #endif 120 } 121 122 123 /* get_des_char: return next char in an encrypted file */ 124 int 125 get_des_char(FILE *fp) 126 { 127 #ifdef DES 128 if (des_n >= des_ct) { 129 des_n = 0; 130 des_ct = cbc_decode(des_buf, fp); 131 } 132 return (des_ct > 0) ? (unsigned char)des_buf[des_n++] : EOF; 133 #else 134 return (getc(fp)); 135 #endif 136 } 137 138 139 /* put_des_char: write a char to an encrypted file; return char written */ 140 int 141 put_des_char(int c, FILE *fp) 142 { 143 #ifdef DES 144 if (des_n == sizeof des_buf) { 145 des_ct = cbc_encode(des_buf, des_n, fp); 146 des_n = 0; 147 } 148 return (des_ct >= 0) ? (des_buf[des_n++] = (char)(unsigned char)c) : EOF; 149 #else 150 return (fputc(c, fp)); 151 #endif 152 } 153 154 155 /* flush_des_file: flush an encrypted file's output; return status */ 156 int 157 flush_des_file(FILE *fp) 158 { 159 #ifdef DES 160 if (des_n == sizeof des_buf) { 161 des_ct = cbc_encode(des_buf, des_n, fp); 162 des_n = 0; 163 } 164 return (des_ct >= 0 && cbc_encode(des_buf, des_n, fp) >= 0) ? 0 : EOF; 165 #else 166 return (fflush(fp)); 167 #endif 168 } 169 170 #ifdef DES 171 /* 172 * get keyword from tty or stdin 173 */ 174 int 175 get_keyword(void) 176 { 177 char *p; /* used to obtain the key */ 178 Desbuf msgbuf; /* I/O buffer */ 179 180 /* 181 * get the key 182 */ 183 if (*(p = getpass("Enter key: "))) { 184 185 /* 186 * copy it, nul-padded, into the key area 187 */ 188 expand_des_key(BUFFER(msgbuf), p); 189 MEMZERO(p, _PASSWORD_LEN); 190 set_des_key(msgbuf); 191 MEMZERO(msgbuf, sizeof msgbuf); 192 return 1; 193 } 194 return 0; 195 } 196 197 198 /* 199 * print a warning message and, possibly, terminate 200 */ 201 void 202 des_error(const char *s) 203 { 204 sprintf(errmsg, "%s", s ? s : strerror(errno)); 205 } 206 207 /* 208 * map a hex character to an integer 209 */ 210 int 211 hex_to_binary(int c, int radix) 212 { 213 switch(c) { 214 case '0': return(0x0); 215 case '1': return(0x1); 216 case '2': return(radix > 2 ? 0x2 : -1); 217 case '3': return(radix > 3 ? 0x3 : -1); 218 case '4': return(radix > 4 ? 0x4 : -1); 219 case '5': return(radix > 5 ? 0x5 : -1); 220 case '6': return(radix > 6 ? 0x6 : -1); 221 case '7': return(radix > 7 ? 0x7 : -1); 222 case '8': return(radix > 8 ? 0x8 : -1); 223 case '9': return(radix > 9 ? 0x9 : -1); 224 case 'A': case 'a': return(radix > 10 ? 0xa : -1); 225 case 'B': case 'b': return(radix > 11 ? 0xb : -1); 226 case 'C': case 'c': return(radix > 12 ? 0xc : -1); 227 case 'D': case 'd': return(radix > 13 ? 0xd : -1); 228 case 'E': case 'e': return(radix > 14 ? 0xe : -1); 229 case 'F': case 'f': return(radix > 15 ? 0xf : -1); 230 } 231 /* 232 * invalid character 233 */ 234 return(-1); 235 } 236 237 /* 238 * convert the key to a bit pattern 239 */ 240 void 241 expand_des_key(char *obuf, char *inbuf) 242 { 243 int i, j; /* counter in a for loop */ 244 int nbuf[64]; /* used for hex/key translation */ 245 246 /* 247 * leading '0x' or '0X' == hex key 248 */ 249 if (inbuf[0] == '0' && (inbuf[1] == 'x' || inbuf[1] == 'X')) { 250 inbuf = &inbuf[2]; 251 /* 252 * now translate it, bombing on any illegal hex digit 253 */ 254 for (i = 0; inbuf[i] && i < 16; i++) 255 if ((nbuf[i] = hex_to_binary((int) inbuf[i], 16)) == -1) 256 des_error("bad hex digit in key"); 257 while (i < 16) 258 nbuf[i++] = 0; 259 for (i = 0; i < 8; i++) 260 obuf[i] = 261 ((nbuf[2*i]&0xf)<<4) | (nbuf[2*i+1]&0xf); 262 /* preserve parity bits */ 263 pflag = 1; 264 return; 265 } 266 /* 267 * leading '0b' or '0B' == binary key 268 */ 269 if (inbuf[0] == '0' && (inbuf[1] == 'b' || inbuf[1] == 'B')) { 270 inbuf = &inbuf[2]; 271 /* 272 * now translate it, bombing on any illegal binary digit 273 */ 274 for (i = 0; inbuf[i] && i < 16; i++) 275 if ((nbuf[i] = hex_to_binary((int) inbuf[i], 2)) == -1) 276 des_error("bad binary digit in key"); 277 while (i < 64) 278 nbuf[i++] = 0; 279 for (i = 0; i < 8; i++) 280 for (j = 0; j < 8; j++) 281 obuf[i] = (obuf[i]<<1)|nbuf[8*i+j]; 282 /* preserve parity bits */ 283 pflag = 1; 284 return; 285 } 286 /* 287 * no special leader -- ASCII 288 */ 289 strncpy(obuf, inbuf, 8); 290 } 291 292 /***************** 293 * DES FUNCTIONS * 294 *****************/ 295 /* 296 * This sets the DES key and (if you're using the deszip version) 297 * the direction of the transformation. This uses the Sun 298 * to map the 64-bit key onto the 56 bits that the key schedule 299 * generation routines use: the old way, which just uses the user- 300 * supplied 64 bits as is, and the new way, which resets the parity 301 * bit to be the same as the low-order bit in each character. The 302 * new way generates a greater variety of key schedules, since many 303 * systems set the parity (high) bit of each character to 0, and the 304 * DES ignores the low order bit of each character. 305 */ 306 void 307 set_des_key(Desbuf buf) 308 { 309 int i, j; /* counter in a for loop */ 310 int par; /* parity counter */ 311 312 /* 313 * if the parity is not preserved, flip it 314 */ 315 if (!pflag) { 316 for (i = 0; i < 8; i++) { 317 par = 0; 318 for (j = 1; j < 8; j++) 319 if ((bits[j]&UCHAR(buf, i)) != 0) 320 par++; 321 if ((par&01) == 01) 322 UCHAR(buf, i) = UCHAR(buf, i)&0177; 323 else 324 UCHAR(buf, i) = (UCHAR(buf, i)&0177)|0200; 325 } 326 } 327 328 DES_KEY(UBUFFER(buf)); 329 } 330 331 332 /* 333 * This encrypts using the Cipher Block Chaining mode of DES 334 */ 335 int 336 cbc_encode(char *msgbuf, int n, FILE *fp) 337 { 338 int inverse = 0; /* 0 to encrypt, 1 to decrypt */ 339 340 /* 341 * do the transformation 342 */ 343 if (n == 8) { 344 for (n = 0; n < 8; n++) 345 CHAR(msgbuf, n) ^= CHAR(ivec, n); 346 DES_XFORM(UBUFFER(msgbuf)); 347 MEMCPY(BUFFER(ivec), BUFFER(msgbuf), 8); 348 return WRITE(BUFFER(msgbuf), 8, fp); 349 } 350 /* 351 * at EOF or last block -- in either case, the last byte contains 352 * the character representation of the number of bytes in it 353 */ 354 /* 355 MEMZERO(msgbuf + n, 8 - n); 356 */ 357 /* 358 * Pad the last block randomly 359 */ 360 MEMCPY(BUFFER(msgbuf + n), BUFFER(pvec), 8 - n); 361 CHAR(msgbuf, 7) = n; 362 for (n = 0; n < 8; n++) 363 CHAR(msgbuf, n) ^= CHAR(ivec, n); 364 DES_XFORM(UBUFFER(msgbuf)); 365 return WRITE(BUFFER(msgbuf), 8, fp); 366 } 367 368 /* 369 * This decrypts using the Cipher Block Chaining mode of DES 370 */ 371 int 372 cbc_decode(char *msgbuf, FILE *fp) 373 { 374 Desbuf inbuf; /* temp buffer for initialization vector */ 375 int n; /* number of bytes actually read */ 376 int c; /* used to test for EOF */ 377 int inverse = 1; /* 0 to encrypt, 1 to decrypt */ 378 379 if ((n = READ(BUFFER(msgbuf), 8, fp)) == 8) { 380 /* 381 * do the transformation 382 */ 383 MEMCPY(BUFFER(inbuf), BUFFER(msgbuf), 8); 384 DES_XFORM(UBUFFER(msgbuf)); 385 for (c = 0; c < 8; c++) 386 UCHAR(msgbuf, c) ^= UCHAR(ivec, c); 387 MEMCPY(BUFFER(ivec), BUFFER(inbuf), 8); 388 /* 389 * if the last one, handle it specially 390 */ 391 if ((c = fgetc(fp)) == EOF) { 392 n = CHAR(msgbuf, 7); 393 if (n < 0 || n > 7) { 394 des_error("decryption failed (block corrupted)"); 395 return EOF; 396 } 397 } else 398 ungetc(c, fp); 399 return n; 400 } 401 if (n > 0) 402 des_error("decryption failed (incomplete block)"); 403 else if (n < 0) 404 des_error("cannot read file"); 405 return EOF; 406 } 407 #endif /* DES */ 408