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1 | /* -*-c-*- |
2 | * |
b80cbed5 |
3 | * $Id: keygen.c,v 1.3 1997/09/17 15:29:28 mdw Exp $ |
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4 | * |
5 | * Key generation |
6 | * |
7 | * (c) 1997 EBI |
8 | */ |
9 | |
03f996bd |
10 | /*----- Licensing notice --------------------------------------------------* |
c4f2d992 |
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 |
03f996bd |
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 1.3 1997/09/17 15:29:28 mdw |
33 | * Mix the noise from the key timings with some other environmental noise |
34 | * (obtained from `noise_acquire') for a little bit more randomness. |
35 | * |
03f996bd |
36 | * Revision 1.2 1997/08/04 10:24:23 mdw |
37 | * Sources placed under CVS control. |
38 | * |
39 | * Revision 1.1 1997/07/21 13:47:48 mdw |
c4f2d992 |
40 | * Initial revision |
41 | * |
42 | */ |
43 | |
44 | /*----- Header files ------------------------------------------------------*/ |
45 | |
46 | /* --- ANSI headers --- */ |
47 | |
48 | #include <ctype.h> |
49 | #include <errno.h> |
50 | #include <signal.h> |
51 | #include <stdio.h> |
52 | #include <stdlib.h> |
53 | #include <string.h> |
54 | |
55 | /* --- Unix headers --- */ |
56 | |
57 | #include <sys/types.h> |
58 | #include <sys/time.h> |
59 | #include <fcntl.h> |
60 | |
61 | #include <termios.h> |
62 | #include <unistd.h> |
63 | |
64 | /* --- Local headers --- */ |
65 | |
66 | #include "config.h" |
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67 | #include "mdwopt.h" |
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68 | #include "noise.h" |
69 | #include "rand.h" |
70 | #include "tx.h" |
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71 | #include "utils.h" |
72 | |
73 | /*----- Static variables --------------------------------------------------*/ |
74 | |
75 | static struct termios kg__raw, kg__old; /* Terminal settings */ |
76 | static int kg__tty; /* File handle for the terminal */ |
77 | static FILE *kg__ttyfp; /* Stream pointer for terminal */ |
78 | static unsigned int kg__flags; /* Various interesting flags */ |
79 | |
80 | enum { |
81 | kgFlag__cbreak = 1 /* Terminal is in cbreak mode */ |
82 | }; |
83 | |
84 | /*----- Main code ---------------------------------------------------------*/ |
85 | |
86 | /* --- @kg__cbreak@ --- * |
87 | * |
88 | * Arguments: --- |
89 | * |
90 | * Returns: --- |
91 | * |
92 | * Use: Makes the terminal return characters as soon as they're |
93 | * asked for. |
94 | */ |
95 | |
96 | void kg__cbreak(void) |
97 | { |
98 | /* --- Don't do this if I don't have to --- */ |
99 | |
100 | if (kg__flags & kgFlag__cbreak) |
101 | return; |
102 | |
103 | /* --- Fetch the old attributes, and remember them --- */ |
104 | |
105 | if (tcgetattr(kg__tty, &kg__old)) |
106 | die("couldn't read terminal attributes: %s", strerror(errno)); |
107 | memcpy(&kg__raw, &kg__old, sizeof(kg__raw)); |
108 | |
109 | /* --- Now modify them for raw mode --- */ |
110 | |
111 | kg__raw.c_lflag &= ~(ICANON | ECHO); |
112 | kg__raw.c_cc[VTIME] = 0; |
113 | kg__raw.c_cc[VMIN] = 1; |
114 | |
115 | /* --- Remember the new state, and away we go --- */ |
116 | |
117 | kg__flags |= kgFlag__cbreak; |
118 | if (tcsetattr(kg__tty, TCSAFLUSH, &kg__raw)) |
119 | die("couldn't set terminal attributes: %s", strerror(errno)); |
120 | } |
121 | |
122 | /* --- @kg__crepair@ --- * |
123 | * |
124 | * Arguments: --- |
125 | * |
126 | * Returns: --- |
127 | * |
128 | * Use: Unbreaks a cbroken tty. Obvious, innit? |
129 | */ |
130 | |
131 | static void kg__crepair(void) |
132 | { |
133 | /* --- Don't do this if I don't have to --- */ |
134 | |
135 | if (~kg__flags & kgFlag__cbreak) |
136 | return; |
137 | |
138 | /* --- Reset the old attributes --- */ |
139 | |
140 | tcsetattr(kg__tty, TCSAFLUSH, &kg__old); |
141 | kg__flags &= ~kgFlag__cbreak; |
142 | } |
143 | |
144 | /* --- @kg__signal@ --- * |
145 | * |
146 | * Arguments: @int sig@ = signal number |
147 | * |
148 | * Returns: --- |
149 | * |
150 | * Use: Tidies up if I get a signal. |
151 | */ |
152 | |
153 | static void kg__signal(int sig) |
154 | { |
155 | kg__crepair(); |
156 | signal(sig, SIG_DFL); |
157 | raise(sig); |
158 | } |
159 | |
160 | /* --- @kgFmt__binary@ --- * |
161 | * |
162 | * Arguments: @unsigned char *k@ = pointer to key buffer |
163 | * @size_t bits@ = number of bits to write |
164 | * @FILE *fp@ = stream to write on |
165 | * |
166 | * Returns: --- |
167 | * |
168 | * Use: Writes bits on a stream. |
169 | */ |
170 | |
171 | static void kgFmt__binary(unsigned char *k, size_t bits, FILE *fp) |
172 | { |
173 | fwrite(k, 1, bits / 8, fp); |
174 | } |
175 | |
176 | /* --- @kgFmt__base64@ --- * |
177 | * |
178 | * Arguments: @unsigned char *k@ = pointer to key buffer |
179 | * @size_t bits@ = number of bits to write |
180 | * @FILE *fp@ = stream to write on |
181 | * |
182 | * Returns: --- |
183 | * |
184 | * Use: Writes bits on a stream in an encoded way. |
185 | */ |
186 | |
187 | static void kgFmt__base64(unsigned char *k, size_t bits, FILE *fp) |
188 | { |
189 | static const char xlt[64] = { "ABCDEFGHIJKLMNOPQRSTUVWXYZ" |
190 | "abcdefghijklmnopqrstuvwxyz" |
191 | "0123456789+/" }; |
192 | unsigned long b; |
193 | int ll = 0; |
194 | |
195 | while (bits > 24) { |
196 | b = ((k[0] & 0xffu) << 16) | ((k[1] & 0xffu) << 8) | (k[2] & 0xffu); |
197 | k += 3; |
198 | bits -= 24; |
199 | putc(xlt[(b >> 18) & 0x3fu], fp); |
200 | putc(xlt[(b >> 12) & 0x3fu], fp); |
201 | putc(xlt[(b >> 6) & 0x3fu], fp); |
202 | putc(xlt[(b >> 0) & 0x3fu], fp); |
203 | if ((ll += 4) > 70) { |
204 | putc('\n', fp); |
205 | ll = 0; |
206 | } |
207 | } |
208 | |
209 | b = 0; |
210 | switch (bits) { |
211 | case 24: |
212 | b = *k++ & 0xffu; |
213 | case 16: |
214 | b = (b << 8) | (*k++ & 0xffu); |
215 | case 8: |
216 | b = (b << 8) | (*k++ & 0xffu); |
217 | } |
218 | b <<= (24 - bits); |
219 | putc(xlt[(b >> 18) & 0x3fu], fp); |
220 | putc(xlt[(b >> 12) & 0x3fu], fp); |
221 | switch (bits) { |
222 | case 24: |
223 | putc(xlt[(b >> 6) & 0x3fu], fp); |
224 | putc(xlt[(b >> 0) & 0x3fu], fp); |
225 | break; |
226 | case 16: |
227 | putc(xlt[(b >> 6) & 0x3fu], fp); |
228 | putc('=', fp); |
229 | break; |
230 | case 8: |
231 | fputs("==", fp); |
232 | break; |
233 | } |
234 | |
235 | putc('\n', fp); |
236 | } |
237 | |
238 | /* --- @kg__gen@ --- * |
239 | * |
240 | * Arguments: @unsigned char *ui@ = pointer to array to fill in |
241 | * @size_t sz@ = number of bits to generate |
242 | * |
243 | * Returns: --- |
244 | * |
245 | * Use: Uses key timings to generate random numbers. Maybe. |
246 | */ |
247 | |
248 | static void kg__gen(unsigned char *ui, size_t sz) |
249 | { |
250 | int bits = 32 < sz ? 32 : sz; |
251 | size_t wsz = (sz + 31u) & ~31u; |
252 | unsigned long last, ldiff = 0; |
253 | unsigned long a = 0; |
254 | unsigned long fact = 1000000 / CLOCKS_PER_SEC; |
255 | |
256 | fprintf(kg__ttyfp, |
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257 | "I need to get %lu random bits; I'll do this by timing your keypresses.\n" |
c4f2d992 |
258 | "Please type some arbitrary text until I say `done'.\n", |
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259 | (unsigned long)sz); |
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260 | |
261 | { |
262 | struct timeval tv; |
263 | gettimeofday(&tv, 0); |
264 | last = tv.tv_usec / fact + tv.tv_sec * fact; |
265 | } |
266 | |
267 | while (sz) { |
268 | int useful; |
269 | uint_32 orr, xor; |
270 | |
271 | /* --- Print current status --- */ |
272 | |
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273 | fprintf(kg__ttyfp, "\r%5lu...", (unsigned long)sz); |
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274 | fflush(kg__ttyfp); |
275 | |
276 | /* --- Read the next character --- */ |
277 | |
278 | { |
279 | char buff[16]; |
280 | if (read(kg__tty, buff, sizeof(buff)) < 0) |
281 | die("couldn't read from terminal: %s", strerror(errno)); |
282 | } |
283 | |
284 | /* --- Fiddle with times --- * |
285 | * |
286 | * Read the time now. Turn it into 32 bits of useful information, and |
287 | * find the difference between that and the previous time. Compare this |
288 | * with the difference between the previous pair of keypresses. |
289 | */ |
290 | |
291 | { |
292 | struct timeval tv; |
293 | uint_32 n, nd; |
294 | |
295 | gettimeofday(&tv, 0); |
296 | n = tv.tv_usec / fact + tv.tv_sec * fact; |
297 | if (!ldiff) { |
298 | ldiff = n - last; |
299 | last = n; |
300 | continue; |
301 | } |
302 | nd = n - last; |
303 | orr = nd | ldiff; |
304 | xor = nd ^ ldiff; |
305 | D( printf("\nlast = %08lx, next = %08lx, ldiff = %08lx, nd = %08lx\n", |
306 | (unsigned long)last, (unsigned long)n, |
307 | (unsigned long)ldiff, (unsigned long)nd); |
308 | printf("xor = %08lx\n", (unsigned long)xor); ) |
309 | ldiff = nd; |
310 | last = n; |
311 | } |
312 | |
313 | /* --- Find the useful bits in this value --- * |
314 | * |
315 | * Find the least significant set bit in @bowl@ and chop it off. Then |
316 | * find the most significant set bit and chop that off two. The rest is |
317 | * probably interesting. |
318 | */ |
319 | |
320 | { |
321 | unsigned long i; |
322 | |
323 | if (!orr || !xor) |
324 | continue; /* erk! */ |
325 | |
326 | useful = 30; |
327 | |
328 | i = 0x80000000ul; |
329 | if (xor & i) { |
330 | while (i && (xor & i) != 0) { |
331 | i >>= 1; |
332 | useful--; |
333 | } |
334 | } else { |
335 | while (i && (xor & i) == 0) { |
336 | i >>= 1; |
337 | useful--; |
338 | } |
339 | } |
340 | xor &= ~-i; |
341 | |
342 | while ((orr & 1) == 0) { |
343 | useful--; |
344 | orr >>= 1; |
345 | xor >>= 1; |
346 | } |
347 | xor >>= 1; |
348 | |
349 | if (useful < 1) |
350 | continue; |
351 | } |
352 | |
353 | /* --- Now add the bits in the mixing bowl to my stash --- * |
354 | * |
355 | * There are two cases: |
356 | * |
357 | * 1. I have more bits than will fit into the accumulator. Then I must |
358 | * put as many bits into the accumulator as will fit, store the |
359 | * accumulator, and remove the spent bits. |
360 | * |
361 | * 2. I have too few bits to fit in the accumulator. Then shift them |
362 | * in and return. |
363 | */ |
364 | |
365 | while (sz && useful) { |
366 | |
367 | D( printf("got %i bits, need %i/%i: %8lx\n", |
368 | useful, bits, sz, (unsigned long)xor); ) |
369 | |
370 | if (useful >= bits) { |
371 | |
372 | D( printf("shifted acc = %08lx\n" |
373 | " new bits = %08lx\n" |
374 | " result = %08lx\n", |
375 | (unsigned long)(a << bits), |
376 | (unsigned long)(xor >> (useful - bits)), |
377 | (unsigned long)((a << bits) | (xor >> (useful - bits)))); ) |
378 | |
379 | a = (a << bits) | (xor >> (useful - bits)); |
380 | |
381 | sz -= bits; |
382 | wsz -= bits; |
383 | useful -= bits; |
384 | |
385 | if (sz == 0) { |
386 | a <<= wsz; |
387 | bits = 32 - wsz; |
388 | } else |
389 | bits = 32; |
390 | |
391 | while (bits > 0) { |
392 | D( printf("writing %02x\n", (a >> 24) & 0xffu); ) |
393 | *ui++ = (a >> 24) & 0xffu; |
394 | a <<= 8; |
395 | bits -= 8; |
396 | } |
397 | a = 0; |
398 | |
399 | bits = 32 < sz ? 32 : sz; |
400 | |
401 | } else { |
402 | |
403 | D( printf("shifted acc = %08lx\n" |
404 | " new bits = %08lx\n" |
405 | " result = %08lx\n", |
406 | (unsigned long)(a << useful), |
407 | (unsigned long)(xor), |
408 | (unsigned long)((a << useful) | (xor))); ) |
409 | a = (a << useful) | xor; |
410 | bits -= useful; |
411 | sz -= useful; |
412 | wsz -= useful; |
413 | useful = 0; |
414 | } |
415 | } |
416 | } |
417 | |
418 | fputs("\rDone! \n", kg__ttyfp); |
419 | putc('\a', kg__ttyfp); fflush(kg__ttyfp); |
420 | sleep(1); |
421 | } |
422 | |
423 | /* --- @main@ --- * |
424 | * |
425 | * Arguments: @int argc@ = number of arguments |
426 | * @char *argv[]@ = array of arguments |
427 | * |
428 | * Returns: Zero if it worked, nonzero if it didn't. |
429 | * |
430 | * Use: Generates random numbers from the keyboard. |
431 | */ |
432 | |
433 | int main(int argc, char *argv[]) |
434 | { |
435 | unsigned char *uip; |
436 | size_t sz = 128; |
437 | const char *file = 0; |
438 | FILE *fp; |
439 | |
440 | /* --- Formats table --- */ |
441 | |
442 | static struct { |
443 | const char *name; |
444 | void (*proc)(unsigned char *k, size_t bits, FILE *fp); |
445 | } format[] = { |
446 | { "tx", tx_putBits }, |
447 | { "hex", tx_putBits }, |
448 | { "binary", kgFmt__binary }, |
449 | { "base64", kgFmt__base64 }, |
450 | { 0, 0 } |
451 | }; |
452 | |
453 | void (*fmt)(unsigned char *, size_t, FILE *) = tx_putBits; |
454 | |
455 | /* --- Explain who I am --- */ |
456 | |
457 | ego(argv[0]); |
458 | |
459 | /* --- Read arguments --- */ |
460 | |
461 | for (;;) { |
462 | static struct option opts[] = { |
463 | { "help", 0, 0, 'h' }, |
464 | { "bits", gFlag_argReq, 0, 'b' }, |
465 | { "output", gFlag_argReq, 0, 'o' }, |
466 | { "format", gFlag_argReq, 0, 'f' }, |
467 | { 0, 0, 0, 0 } |
468 | }; |
469 | |
470 | int i = mdwopt(argc, argv, "hb:o:f:", opts, 0, 0, 0); |
471 | |
472 | if (i < 0) |
473 | break; |
474 | switch (i) { |
475 | case 'h': |
476 | printf("" |
477 | "Usage: %s [--bits=BITS] [--output=FILE] [--format=FORMAT]\n" |
478 | "\n" |
479 | "Generates BITS (by default, 128) random bits by timing keypresses. The\n" |
480 | "resulting number is written to FILE, or standard output in the given\n" |
481 | "format. Formats currently supported are:\n" |
482 | "\n" |
483 | "tx, hex Hexadecimal, with punctuating dashes.\n" |
484 | "binary Raw binary.\n" |
485 | "base64 Base64-encoded binary; the result is printable ASCII.\n", |
486 | quis()); |
487 | exit(0); |
488 | break; |
489 | case 'b': |
490 | sz = atoi(optarg); |
491 | if (sz == 0) |
492 | die("bad number of bits (illegible or zero)"); |
493 | if (sz % 8) |
494 | die("can only generate a whole number of 8-bit bytes"); |
495 | break; |
496 | case 'o': |
497 | file = optarg; |
498 | break; |
499 | case 'f': |
500 | fmt = 0; |
501 | for (i = 0; format[i].name; i++) { |
502 | const char *p = format[i].name, *q = optarg; |
503 | for (;;) { |
504 | if (*q == 0) |
505 | break; |
506 | if (*p != *q) |
507 | break; |
508 | p++, q++; |
509 | } |
510 | if (!*q) { |
511 | if (fmt) |
512 | die("ambiguous format name: `%s'", optarg); |
513 | fmt = format[i].proc; |
514 | } |
515 | } |
516 | if (!fmt) |
517 | die("unknown format name: `%s'", optarg); |
518 | break; |
519 | case '?': |
520 | exit(1); |
521 | break; |
522 | } |
523 | } |
524 | |
525 | if (optind < argc) { |
526 | fprintf(stderr, "Usage: %s [--bits=BITS] [--output=FILE]\n", quis()); |
527 | exit(1); |
528 | } |
529 | |
530 | /* --- Allocate memory --- */ |
531 | |
532 | uip = xmalloc(sz / 8); |
533 | |
534 | /* --- Open the terminal --- * |
535 | * |
536 | * I'd like to be able to @fprintf@ to the terminal, so use @fopen@. |
537 | */ |
538 | |
539 | if ((kg__ttyfp = fopen("/dev/tty", "r+")) == 0) |
540 | die("couldn't open terminal: %s", strerror(errno)); |
541 | kg__tty = fileno(kg__ttyfp); |
542 | |
543 | /* --- Open the output file, if one is specified --- */ |
544 | |
545 | if (file) { |
546 | int fd; |
547 | |
548 | /* --- Open the file oddly --- * |
549 | * |
550 | * There's a good reason for this. I want to be able to @fprintf@ (for |
551 | * the benefit of @tx_putWords@ mainly) but I also want to ensure that |
552 | * only the user has read permissions for the file. So I'll use @open@ |
553 | * with an appropriate mode and then @fdopen@ the file descriptor to get |
554 | * a stream. Yuk. |
555 | */ |
556 | |
557 | if ((fd = open(file, O_WRONLY | O_CREAT | O_TRUNC, 0600)) < 0) |
558 | die("couldn't open output file: %s", strerror(errno)); |
559 | if ((fp = fdopen(fd, "w")) == 0) |
560 | die("couldn't attach stream to output file: %s", strerror(errno)); |
561 | } else |
562 | fp = stdout; |
563 | |
564 | /* --- Tidy up nicely if I die --- */ |
565 | |
566 | signal(SIGINT, kg__signal); |
567 | signal(SIGTERM, kg__signal); |
568 | atexit(kg__crepair); |
569 | |
570 | /* --- Put the terminal into cbreak, read the key, and restore --- */ |
571 | |
572 | kg__cbreak(); |
573 | kg__gen(uip, sz); |
574 | kg__crepair(); |
575 | |
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576 | /* --- Find some noise from the environment too --- */ |
577 | |
578 | rand_clear(); |
579 | noise_acquire(); |
580 | rand_add(uip, sz / 8); |
581 | rand_churn(); |
582 | rand_extract(uip, sz / 8); |
583 | |
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584 | /* --- Now write the number and exit --- */ |
585 | |
586 | D( fputs("*** ", fp); tx_putBits(uip, sz, stdout); ) |
587 | fmt(uip, sz, fp); |
588 | if (file) |
589 | fclose(fp); |
590 | memset(uip, 0, sz / 8); /* Burn temporary buffer */ |
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591 | rand_clear(); |
c4f2d992 |
592 | return (0); |
593 | } |
594 | |
595 | /*----- That's all, folks -------------------------------------------------*/ |