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comparison libtommath/bn_mp_exptmod_fast.c @ 348:cd14c94fe89c debug-unrandom

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add some more copious debugging
author Matt Johnston <matt@ucc.asn.au>
date Sun, 06 Aug 2006 15:29:41 +0000
parents eed26cff980b
children e66eec4dcba7
comparison
equal deleted inserted replaced
347:381834084475 348:cd14c94fe89c
1 #include "../dbutil.h"
1 #include <tommath.h> 2 #include <tommath.h>
2 #ifdef BN_MP_EXPTMOD_FAST_C 3 #ifdef BN_MP_EXPTMOD_FAST_C
3 /* LibTomMath, multiple-precision integer library -- Tom St Denis 4 /* LibTomMath, multiple-precision integer library -- Tom St Denis
4 * 5 *
5 * LibTomMath is a library that provides multiple-precision 6 * LibTomMath is a library that provides multiple-precision
63 if (winsize > 5) { 64 if (winsize > 5) {
64 winsize = 5; 65 winsize = 5;
65 } 66 }
66 #endif 67 #endif
67 68
69 dropbear_trace("mp_exptmod_fast x bits %d redmode %d", x, redmode);
70
68 /* init M array */ 71 /* init M array */
69 /* init first cell */ 72 /* init first cell */
70 if ((err = mp_init(&M[1])) != MP_OKAY) { 73 if ((err = mp_init(&M[1])) != MP_OKAY) {
71 return err; 74 return err;
72 } 75 }
208 /* read next digit and reset bitcnt */ 211 /* read next digit and reset bitcnt */
209 buf = X->dp[digidx--]; 212 buf = X->dp[digidx--];
210 bitcnt = (int)DIGIT_BIT; 213 bitcnt = (int)DIGIT_BIT;
211 } 214 }
212 215
216 dropbear_trace("mp_exptmod_fast digidx %d buf %u", digidx+1, buf);
217
213 /* grab the next msb from the exponent */ 218 /* grab the next msb from the exponent */
214 y = (mp_digit)(buf >> (DIGIT_BIT - 1)) & 1; 219 y = (mp_digit)(buf >> (DIGIT_BIT - 1)) & 1;
215 buf <<= (mp_digit)1; 220 buf <<= (mp_digit)1;
216 221
217 /* if the bit is zero and mode == 0 then we ignore it 222 /* if the bit is zero and mode == 0 then we ignore it
229 goto LBL_RES; 234 goto LBL_RES;
230 } 235 }
231 if ((err = redux (&res, P, mp)) != MP_OKAY) { 236 if ((err = redux (&res, P, mp)) != MP_OKAY) {
232 goto LBL_RES; 237 goto LBL_RES;
233 } 238 }
239 print_mp_int("mp_exptmod_fast bit=0 mode=1 sq", &res);
234 continue; 240 continue;
235 } 241 }
236 242
237 /* else we add it to the window */ 243 /* else we add it to the window */
238 bitbuf |= (y << (winsize - ++bitcpy)); 244 bitbuf |= (y << (winsize - ++bitcpy));
261 /* empty window and reset */ 267 /* empty window and reset */
262 bitcpy = 0; 268 bitcpy = 0;
263 bitbuf = 0; 269 bitbuf = 0;
264 mode = 1; 270 mode = 1;
265 } 271 }
272 print_mp_int("mp_exptmod_fast other way", &res);
266 } 273 }
267 274
268 /* if bits remain then square/multiply */ 275 /* if bits remain then square/multiply */
269 if (mode == 2 && bitcpy > 0) { 276 if (mode == 2 && bitcpy > 0) {
270 /* square then multiply if the bit is set */ 277 /* square then multiply if the bit is set */
287 goto LBL_RES; 294 goto LBL_RES;
288 } 295 }
289 } 296 }
290 } 297 }
291 } 298 }
299 print_mp_int("mp_exptmod_fast remaining bits", &res);
292 300
293 if (redmode == 0) { 301 if (redmode == 0) {
294 /* fixup result if Montgomery reduction is used 302 /* fixup result if Montgomery reduction is used
295 * recall that any value in a Montgomery system is 303 * recall that any value in a Montgomery system is
296 * actually multiplied by R mod n. So we have 304 * actually multiplied by R mod n. So we have
298 * of R. 306 * of R.
299 */ 307 */
300 if ((err = redux(&res, P, mp)) != MP_OKAY) { 308 if ((err = redux(&res, P, mp)) != MP_OKAY) {
301 goto LBL_RES; 309 goto LBL_RES;
302 } 310 }
311 print_mp_int("mp_exptmod_fast fixup", &res);
303 } 312 }
304 313
305 /* swap res with Y */ 314 /* swap res with Y */
306 mp_exch (&res, Y); 315 mp_exch (&res, Y);
307 err = MP_OKAY; 316 err = MP_OKAY;