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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: keygen.c,v 1.2 1997/08/04 10:24:23 mdw Exp $ |
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4 | * |
5 | * Key generation |
6 | * |
7 | * (c) 1997 EBI |
8 | */ |
9 | |
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10 | /*----- Licensing notice --------------------------------------------------* |
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11 | * |
12 | * This file is part of `become' |
13 | * |
14 | * `Become' is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU General Public License as published by |
16 | * the Free Software Foundation; either version 2 of the License, or |
17 | * (at your option) any later version. |
18 | * |
19 | * `Become' is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU General Public License |
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25 | * along with `become'; if not, write to the Free Software Foundation, |
26 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
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27 | */ |
28 | |
29 | /*----- Revision history --------------------------------------------------* |
30 | * |
31 | * $Log: keygen.c,v $ |
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32 | * Revision 1.2 1997/08/04 10:24:23 mdw |
33 | * Sources placed under CVS control. |
34 | * |
35 | * Revision 1.1 1997/07/21 13:47:48 mdw |
c4f2d992 |
36 | * Initial revision |
37 | * |
38 | */ |
39 | |
40 | /*----- Header files ------------------------------------------------------*/ |
41 | |
42 | /* --- ANSI headers --- */ |
43 | |
44 | #include <ctype.h> |
45 | #include <errno.h> |
46 | #include <signal.h> |
47 | #include <stdio.h> |
48 | #include <stdlib.h> |
49 | #include <string.h> |
50 | |
51 | /* --- Unix headers --- */ |
52 | |
53 | #include <sys/types.h> |
54 | #include <sys/time.h> |
55 | #include <fcntl.h> |
56 | |
57 | #include <termios.h> |
58 | #include <unistd.h> |
59 | |
60 | /* --- Local headers --- */ |
61 | |
62 | #include "config.h" |
63 | #include "tx.h" |
64 | #include "mdwopt.h" |
65 | #include "utils.h" |
66 | |
67 | /*----- Static variables --------------------------------------------------*/ |
68 | |
69 | static struct termios kg__raw, kg__old; /* Terminal settings */ |
70 | static int kg__tty; /* File handle for the terminal */ |
71 | static FILE *kg__ttyfp; /* Stream pointer for terminal */ |
72 | static unsigned int kg__flags; /* Various interesting flags */ |
73 | |
74 | enum { |
75 | kgFlag__cbreak = 1 /* Terminal is in cbreak mode */ |
76 | }; |
77 | |
78 | /*----- Main code ---------------------------------------------------------*/ |
79 | |
80 | /* --- @kg__cbreak@ --- * |
81 | * |
82 | * Arguments: --- |
83 | * |
84 | * Returns: --- |
85 | * |
86 | * Use: Makes the terminal return characters as soon as they're |
87 | * asked for. |
88 | */ |
89 | |
90 | void kg__cbreak(void) |
91 | { |
92 | /* --- Don't do this if I don't have to --- */ |
93 | |
94 | if (kg__flags & kgFlag__cbreak) |
95 | return; |
96 | |
97 | /* --- Fetch the old attributes, and remember them --- */ |
98 | |
99 | if (tcgetattr(kg__tty, &kg__old)) |
100 | die("couldn't read terminal attributes: %s", strerror(errno)); |
101 | memcpy(&kg__raw, &kg__old, sizeof(kg__raw)); |
102 | |
103 | /* --- Now modify them for raw mode --- */ |
104 | |
105 | kg__raw.c_lflag &= ~(ICANON | ECHO); |
106 | kg__raw.c_cc[VTIME] = 0; |
107 | kg__raw.c_cc[VMIN] = 1; |
108 | |
109 | /* --- Remember the new state, and away we go --- */ |
110 | |
111 | kg__flags |= kgFlag__cbreak; |
112 | if (tcsetattr(kg__tty, TCSAFLUSH, &kg__raw)) |
113 | die("couldn't set terminal attributes: %s", strerror(errno)); |
114 | } |
115 | |
116 | /* --- @kg__crepair@ --- * |
117 | * |
118 | * Arguments: --- |
119 | * |
120 | * Returns: --- |
121 | * |
122 | * Use: Unbreaks a cbroken tty. Obvious, innit? |
123 | */ |
124 | |
125 | static void kg__crepair(void) |
126 | { |
127 | /* --- Don't do this if I don't have to --- */ |
128 | |
129 | if (~kg__flags & kgFlag__cbreak) |
130 | return; |
131 | |
132 | /* --- Reset the old attributes --- */ |
133 | |
134 | tcsetattr(kg__tty, TCSAFLUSH, &kg__old); |
135 | kg__flags &= ~kgFlag__cbreak; |
136 | } |
137 | |
138 | /* --- @kg__signal@ --- * |
139 | * |
140 | * Arguments: @int sig@ = signal number |
141 | * |
142 | * Returns: --- |
143 | * |
144 | * Use: Tidies up if I get a signal. |
145 | */ |
146 | |
147 | static void kg__signal(int sig) |
148 | { |
149 | kg__crepair(); |
150 | signal(sig, SIG_DFL); |
151 | raise(sig); |
152 | } |
153 | |
154 | /* --- @kgFmt__binary@ --- * |
155 | * |
156 | * Arguments: @unsigned char *k@ = pointer to key buffer |
157 | * @size_t bits@ = number of bits to write |
158 | * @FILE *fp@ = stream to write on |
159 | * |
160 | * Returns: --- |
161 | * |
162 | * Use: Writes bits on a stream. |
163 | */ |
164 | |
165 | static void kgFmt__binary(unsigned char *k, size_t bits, FILE *fp) |
166 | { |
167 | fwrite(k, 1, bits / 8, fp); |
168 | } |
169 | |
170 | /* --- @kgFmt__base64@ --- * |
171 | * |
172 | * Arguments: @unsigned char *k@ = pointer to key buffer |
173 | * @size_t bits@ = number of bits to write |
174 | * @FILE *fp@ = stream to write on |
175 | * |
176 | * Returns: --- |
177 | * |
178 | * Use: Writes bits on a stream in an encoded way. |
179 | */ |
180 | |
181 | static void kgFmt__base64(unsigned char *k, size_t bits, FILE *fp) |
182 | { |
183 | static const char xlt[64] = { "ABCDEFGHIJKLMNOPQRSTUVWXYZ" |
184 | "abcdefghijklmnopqrstuvwxyz" |
185 | "0123456789+/" }; |
186 | unsigned long b; |
187 | int ll = 0; |
188 | |
189 | while (bits > 24) { |
190 | b = ((k[0] & 0xffu) << 16) | ((k[1] & 0xffu) << 8) | (k[2] & 0xffu); |
191 | k += 3; |
192 | bits -= 24; |
193 | putc(xlt[(b >> 18) & 0x3fu], fp); |
194 | putc(xlt[(b >> 12) & 0x3fu], fp); |
195 | putc(xlt[(b >> 6) & 0x3fu], fp); |
196 | putc(xlt[(b >> 0) & 0x3fu], fp); |
197 | if ((ll += 4) > 70) { |
198 | putc('\n', fp); |
199 | ll = 0; |
200 | } |
201 | } |
202 | |
203 | b = 0; |
204 | switch (bits) { |
205 | case 24: |
206 | b = *k++ & 0xffu; |
207 | case 16: |
208 | b = (b << 8) | (*k++ & 0xffu); |
209 | case 8: |
210 | b = (b << 8) | (*k++ & 0xffu); |
211 | } |
212 | b <<= (24 - bits); |
213 | putc(xlt[(b >> 18) & 0x3fu], fp); |
214 | putc(xlt[(b >> 12) & 0x3fu], fp); |
215 | switch (bits) { |
216 | case 24: |
217 | putc(xlt[(b >> 6) & 0x3fu], fp); |
218 | putc(xlt[(b >> 0) & 0x3fu], fp); |
219 | break; |
220 | case 16: |
221 | putc(xlt[(b >> 6) & 0x3fu], fp); |
222 | putc('=', fp); |
223 | break; |
224 | case 8: |
225 | fputs("==", fp); |
226 | break; |
227 | } |
228 | |
229 | putc('\n', fp); |
230 | } |
231 | |
232 | /* --- @kg__gen@ --- * |
233 | * |
234 | * Arguments: @unsigned char *ui@ = pointer to array to fill in |
235 | * @size_t sz@ = number of bits to generate |
236 | * |
237 | * Returns: --- |
238 | * |
239 | * Use: Uses key timings to generate random numbers. Maybe. |
240 | */ |
241 | |
242 | static void kg__gen(unsigned char *ui, size_t sz) |
243 | { |
244 | int bits = 32 < sz ? 32 : sz; |
245 | size_t wsz = (sz + 31u) & ~31u; |
246 | unsigned long last, ldiff = 0; |
247 | unsigned long a = 0; |
248 | unsigned long fact = 1000000 / CLOCKS_PER_SEC; |
249 | |
250 | fprintf(kg__ttyfp, |
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251 | "I need to get %lu random bits; I'll do this by timing your keypresses.\n" |
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252 | "Please type some arbitrary text until I say `done'.\n", |
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253 | (unsigned long)sz); |
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254 | |
255 | { |
256 | struct timeval tv; |
257 | gettimeofday(&tv, 0); |
258 | last = tv.tv_usec / fact + tv.tv_sec * fact; |
259 | } |
260 | |
261 | while (sz) { |
262 | int useful; |
263 | uint_32 orr, xor; |
264 | |
265 | /* --- Print current status --- */ |
266 | |
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267 | fprintf(kg__ttyfp, "\r%5lu...", (unsigned long)sz); |
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268 | fflush(kg__ttyfp); |
269 | |
270 | /* --- Read the next character --- */ |
271 | |
272 | { |
273 | char buff[16]; |
274 | if (read(kg__tty, buff, sizeof(buff)) < 0) |
275 | die("couldn't read from terminal: %s", strerror(errno)); |
276 | } |
277 | |
278 | /* --- Fiddle with times --- * |
279 | * |
280 | * Read the time now. Turn it into 32 bits of useful information, and |
281 | * find the difference between that and the previous time. Compare this |
282 | * with the difference between the previous pair of keypresses. |
283 | */ |
284 | |
285 | { |
286 | struct timeval tv; |
287 | uint_32 n, nd; |
288 | |
289 | gettimeofday(&tv, 0); |
290 | n = tv.tv_usec / fact + tv.tv_sec * fact; |
291 | if (!ldiff) { |
292 | ldiff = n - last; |
293 | last = n; |
294 | continue; |
295 | } |
296 | nd = n - last; |
297 | orr = nd | ldiff; |
298 | xor = nd ^ ldiff; |
299 | D( printf("\nlast = %08lx, next = %08lx, ldiff = %08lx, nd = %08lx\n", |
300 | (unsigned long)last, (unsigned long)n, |
301 | (unsigned long)ldiff, (unsigned long)nd); |
302 | printf("xor = %08lx\n", (unsigned long)xor); ) |
303 | ldiff = nd; |
304 | last = n; |
305 | } |
306 | |
307 | /* --- Find the useful bits in this value --- * |
308 | * |
309 | * Find the least significant set bit in @bowl@ and chop it off. Then |
310 | * find the most significant set bit and chop that off two. The rest is |
311 | * probably interesting. |
312 | */ |
313 | |
314 | { |
315 | unsigned long i; |
316 | |
317 | if (!orr || !xor) |
318 | continue; /* erk! */ |
319 | |
320 | useful = 30; |
321 | |
322 | i = 0x80000000ul; |
323 | if (xor & i) { |
324 | while (i && (xor & i) != 0) { |
325 | i >>= 1; |
326 | useful--; |
327 | } |
328 | } else { |
329 | while (i && (xor & i) == 0) { |
330 | i >>= 1; |
331 | useful--; |
332 | } |
333 | } |
334 | xor &= ~-i; |
335 | |
336 | while ((orr & 1) == 0) { |
337 | useful--; |
338 | orr >>= 1; |
339 | xor >>= 1; |
340 | } |
341 | xor >>= 1; |
342 | |
343 | if (useful < 1) |
344 | continue; |
345 | } |
346 | |
347 | /* --- Now add the bits in the mixing bowl to my stash --- * |
348 | * |
349 | * There are two cases: |
350 | * |
351 | * 1. I have more bits than will fit into the accumulator. Then I must |
352 | * put as many bits into the accumulator as will fit, store the |
353 | * accumulator, and remove the spent bits. |
354 | * |
355 | * 2. I have too few bits to fit in the accumulator. Then shift them |
356 | * in and return. |
357 | */ |
358 | |
359 | while (sz && useful) { |
360 | |
361 | D( printf("got %i bits, need %i/%i: %8lx\n", |
362 | useful, bits, sz, (unsigned long)xor); ) |
363 | |
364 | if (useful >= bits) { |
365 | |
366 | D( printf("shifted acc = %08lx\n" |
367 | " new bits = %08lx\n" |
368 | " result = %08lx\n", |
369 | (unsigned long)(a << bits), |
370 | (unsigned long)(xor >> (useful - bits)), |
371 | (unsigned long)((a << bits) | (xor >> (useful - bits)))); ) |
372 | |
373 | a = (a << bits) | (xor >> (useful - bits)); |
374 | |
375 | sz -= bits; |
376 | wsz -= bits; |
377 | useful -= bits; |
378 | |
379 | if (sz == 0) { |
380 | a <<= wsz; |
381 | bits = 32 - wsz; |
382 | } else |
383 | bits = 32; |
384 | |
385 | while (bits > 0) { |
386 | D( printf("writing %02x\n", (a >> 24) & 0xffu); ) |
387 | *ui++ = (a >> 24) & 0xffu; |
388 | a <<= 8; |
389 | bits -= 8; |
390 | } |
391 | a = 0; |
392 | |
393 | bits = 32 < sz ? 32 : sz; |
394 | |
395 | } else { |
396 | |
397 | D( printf("shifted acc = %08lx\n" |
398 | " new bits = %08lx\n" |
399 | " result = %08lx\n", |
400 | (unsigned long)(a << useful), |
401 | (unsigned long)(xor), |
402 | (unsigned long)((a << useful) | (xor))); ) |
403 | a = (a << useful) | xor; |
404 | bits -= useful; |
405 | sz -= useful; |
406 | wsz -= useful; |
407 | useful = 0; |
408 | } |
409 | } |
410 | } |
411 | |
412 | fputs("\rDone! \n", kg__ttyfp); |
413 | putc('\a', kg__ttyfp); fflush(kg__ttyfp); |
414 | sleep(1); |
415 | } |
416 | |
417 | /* --- @main@ --- * |
418 | * |
419 | * Arguments: @int argc@ = number of arguments |
420 | * @char *argv[]@ = array of arguments |
421 | * |
422 | * Returns: Zero if it worked, nonzero if it didn't. |
423 | * |
424 | * Use: Generates random numbers from the keyboard. |
425 | */ |
426 | |
427 | int main(int argc, char *argv[]) |
428 | { |
429 | unsigned char *uip; |
430 | size_t sz = 128; |
431 | const char *file = 0; |
432 | FILE *fp; |
433 | |
434 | /* --- Formats table --- */ |
435 | |
436 | static struct { |
437 | const char *name; |
438 | void (*proc)(unsigned char *k, size_t bits, FILE *fp); |
439 | } format[] = { |
440 | { "tx", tx_putBits }, |
441 | { "hex", tx_putBits }, |
442 | { "binary", kgFmt__binary }, |
443 | { "base64", kgFmt__base64 }, |
444 | { 0, 0 } |
445 | }; |
446 | |
447 | void (*fmt)(unsigned char *, size_t, FILE *) = tx_putBits; |
448 | |
449 | /* --- Explain who I am --- */ |
450 | |
451 | ego(argv[0]); |
452 | |
453 | /* --- Read arguments --- */ |
454 | |
455 | for (;;) { |
456 | static struct option opts[] = { |
457 | { "help", 0, 0, 'h' }, |
458 | { "bits", gFlag_argReq, 0, 'b' }, |
459 | { "output", gFlag_argReq, 0, 'o' }, |
460 | { "format", gFlag_argReq, 0, 'f' }, |
461 | { 0, 0, 0, 0 } |
462 | }; |
463 | |
464 | int i = mdwopt(argc, argv, "hb:o:f:", opts, 0, 0, 0); |
465 | |
466 | if (i < 0) |
467 | break; |
468 | switch (i) { |
469 | case 'h': |
470 | printf("" |
471 | "Usage: %s [--bits=BITS] [--output=FILE] [--format=FORMAT]\n" |
472 | "\n" |
473 | "Generates BITS (by default, 128) random bits by timing keypresses. The\n" |
474 | "resulting number is written to FILE, or standard output in the given\n" |
475 | "format. Formats currently supported are:\n" |
476 | "\n" |
477 | "tx, hex Hexadecimal, with punctuating dashes.\n" |
478 | "binary Raw binary.\n" |
479 | "base64 Base64-encoded binary; the result is printable ASCII.\n", |
480 | quis()); |
481 | exit(0); |
482 | break; |
483 | case 'b': |
484 | sz = atoi(optarg); |
485 | if (sz == 0) |
486 | die("bad number of bits (illegible or zero)"); |
487 | if (sz % 8) |
488 | die("can only generate a whole number of 8-bit bytes"); |
489 | break; |
490 | case 'o': |
491 | file = optarg; |
492 | break; |
493 | case 'f': |
494 | fmt = 0; |
495 | for (i = 0; format[i].name; i++) { |
496 | const char *p = format[i].name, *q = optarg; |
497 | for (;;) { |
498 | if (*q == 0) |
499 | break; |
500 | if (*p != *q) |
501 | break; |
502 | p++, q++; |
503 | } |
504 | if (!*q) { |
505 | if (fmt) |
506 | die("ambiguous format name: `%s'", optarg); |
507 | fmt = format[i].proc; |
508 | } |
509 | } |
510 | if (!fmt) |
511 | die("unknown format name: `%s'", optarg); |
512 | break; |
513 | case '?': |
514 | exit(1); |
515 | break; |
516 | } |
517 | } |
518 | |
519 | if (optind < argc) { |
520 | fprintf(stderr, "Usage: %s [--bits=BITS] [--output=FILE]\n", quis()); |
521 | exit(1); |
522 | } |
523 | |
524 | /* --- Allocate memory --- */ |
525 | |
526 | uip = xmalloc(sz / 8); |
527 | |
528 | /* --- Open the terminal --- * |
529 | * |
530 | * I'd like to be able to @fprintf@ to the terminal, so use @fopen@. |
531 | */ |
532 | |
533 | if ((kg__ttyfp = fopen("/dev/tty", "r+")) == 0) |
534 | die("couldn't open terminal: %s", strerror(errno)); |
535 | kg__tty = fileno(kg__ttyfp); |
536 | |
537 | /* --- Open the output file, if one is specified --- */ |
538 | |
539 | if (file) { |
540 | int fd; |
541 | |
542 | /* --- Open the file oddly --- * |
543 | * |
544 | * There's a good reason for this. I want to be able to @fprintf@ (for |
545 | * the benefit of @tx_putWords@ mainly) but I also want to ensure that |
546 | * only the user has read permissions for the file. So I'll use @open@ |
547 | * with an appropriate mode and then @fdopen@ the file descriptor to get |
548 | * a stream. Yuk. |
549 | */ |
550 | |
551 | if ((fd = open(file, O_WRONLY | O_CREAT | O_TRUNC, 0600)) < 0) |
552 | die("couldn't open output file: %s", strerror(errno)); |
553 | if ((fp = fdopen(fd, "w")) == 0) |
554 | die("couldn't attach stream to output file: %s", strerror(errno)); |
555 | } else |
556 | fp = stdout; |
557 | |
558 | /* --- Tidy up nicely if I die --- */ |
559 | |
560 | signal(SIGINT, kg__signal); |
561 | signal(SIGTERM, kg__signal); |
562 | atexit(kg__crepair); |
563 | |
564 | /* --- Put the terminal into cbreak, read the key, and restore --- */ |
565 | |
566 | kg__cbreak(); |
567 | kg__gen(uip, sz); |
568 | kg__crepair(); |
569 | |
570 | /* --- Now write the number and exit --- */ |
571 | |
572 | D( fputs("*** ", fp); tx_putBits(uip, sz, stdout); ) |
573 | fmt(uip, sz, fp); |
574 | if (file) |
575 | fclose(fp); |
576 | memset(uip, 0, sz / 8); /* Burn temporary buffer */ |
577 | return (0); |
578 | } |
579 | |
580 | /*----- That's all, folks -------------------------------------------------*/ |