1 /*
2 * ***** BEGIN LICENSE BLOCK *****
3 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
4 *
5 * The contents of this file are subject to the Mozilla Public License Version
6 * 1.1 (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 * http://www.mozilla.org/MPL/
9 *
10 * Software distributed under the License is distributed on an "AS IS" basis,
11 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
12 * for the specific language governing rights and limitations under the
13 * License.
14 *
15 * The Original Code is the Multi-precision Binary Polynomial Arithmetic Library.
16 *
17 * The Initial Developer of the Original Code is
18 * Sun Microsystems, Inc.
19 * Portions created by the Initial Developer are Copyright (C) 2003
20 * the Initial Developer. All Rights Reserved.
21 *
22 * Contributor(s):
23 * Sheueling Chang Shantz <sheueling.chang@sun.com> and
24 * Douglas Stebila <douglas@stebila.ca> of Sun Laboratories.
25 *
26 * Alternatively, the contents of this file may be used under the terms of
27 * either the GNU General Public License Version 2 or later (the "GPL"), or
28 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
29 * in which case the provisions of the GPL or the LGPL are applicable instead
30 * of those above. If you wish to allow use of your version of this file only
31 * under the terms of either the GPL or the LGPL, and not to allow others to
32 * use your version of this file under the terms of the MPL, indicate your
33 * decision by deleting the provisions above and replace them with the notice
34 * and other provisions required by the GPL or the LGPL. If you do not delete
35 * the provisions above, a recipient may use your version of this file under
36 * the terms of any one of the MPL, the GPL or the LGPL.
37 *
38 * ***** END LICENSE BLOCK ***** */
39 /*
40 * Copyright 2007 Sun Microsystems, Inc. All rights reserved.
41 * Use is subject to license terms.
42 *
43 * Sun elects to use this software under the MPL license.
44 */
45
46 #include "mp_gf2m.h"
47 #include "mp_gf2m-priv.h"
48 #include "mplogic.h"
49 #include "mpi-priv.h"
50
51 const mp_digit mp_gf2m_sqr_tb[16] =
52 {
53 0, 1, 4, 5, 16, 17, 20, 21,
54 64, 65, 68, 69, 80, 81, 84, 85
55 };
56
57 /* Multiply two binary polynomials mp_digits a, b.
58 * Result is a polynomial with degree < 2 * MP_DIGIT_BITS - 1.
59 * Output in two mp_digits rh, rl.
60 */
61 #if MP_DIGIT_BITS == 32
62 void
s_bmul_1x1(mp_digit * rh,mp_digit * rl,const mp_digit a,const mp_digit b)63 s_bmul_1x1(mp_digit *rh, mp_digit *rl, const mp_digit a, const mp_digit b)
64 {
65 register mp_digit h, l, s;
66 mp_digit tab[8], top2b = a >> 30;
67 register mp_digit a1, a2, a4;
68
69 a1 = a & (0x3FFFFFFF); a2 = a1 << 1; a4 = a2 << 1;
70
71 tab[0] = 0; tab[1] = a1; tab[2] = a2; tab[3] = a1^a2;
72 tab[4] = a4; tab[5] = a1^a4; tab[6] = a2^a4; tab[7] = a1^a2^a4;
73
74 s = tab[b & 0x7]; l = s;
75 s = tab[b >> 3 & 0x7]; l ^= s << 3; h = s >> 29;
76 s = tab[b >> 6 & 0x7]; l ^= s << 6; h ^= s >> 26;
77 s = tab[b >> 9 & 0x7]; l ^= s << 9; h ^= s >> 23;
78 s = tab[b >> 12 & 0x7]; l ^= s << 12; h ^= s >> 20;
79 s = tab[b >> 15 & 0x7]; l ^= s << 15; h ^= s >> 17;
80 s = tab[b >> 18 & 0x7]; l ^= s << 18; h ^= s >> 14;
81 s = tab[b >> 21 & 0x7]; l ^= s << 21; h ^= s >> 11;
82 s = tab[b >> 24 & 0x7]; l ^= s << 24; h ^= s >> 8;
83 s = tab[b >> 27 & 0x7]; l ^= s << 27; h ^= s >> 5;
84 s = tab[b >> 30 ]; l ^= s << 30; h ^= s >> 2;
85
86 /* compensate for the top two bits of a */
87
88 if (top2b & 01) { l ^= b << 30; h ^= b >> 2; }
89 if (top2b & 02) { l ^= b << 31; h ^= b >> 1; }
90
91 *rh = h; *rl = l;
92 }
93 #else
94 void
s_bmul_1x1(mp_digit * rh,mp_digit * rl,const mp_digit a,const mp_digit b)95 s_bmul_1x1(mp_digit *rh, mp_digit *rl, const mp_digit a, const mp_digit b)
96 {
97 register mp_digit h, l, s;
98 mp_digit tab[16], top3b = a >> 61;
99 register mp_digit a1, a2, a4, a8;
100
101 a1 = a & (0x1FFFFFFFFFFFFFFFULL); a2 = a1 << 1;
102 a4 = a2 << 1; a8 = a4 << 1;
103 tab[ 0] = 0; tab[ 1] = a1; tab[ 2] = a2; tab[ 3] = a1^a2;
104 tab[ 4] = a4; tab[ 5] = a1^a4; tab[ 6] = a2^a4; tab[ 7] = a1^a2^a4;
105 tab[ 8] = a8; tab[ 9] = a1^a8; tab[10] = a2^a8; tab[11] = a1^a2^a8;
106 tab[12] = a4^a8; tab[13] = a1^a4^a8; tab[14] = a2^a4^a8; tab[15] = a1^a2^a4^a8;
107
108 s = tab[b & 0xF]; l = s;
109 s = tab[b >> 4 & 0xF]; l ^= s << 4; h = s >> 60;
110 s = tab[b >> 8 & 0xF]; l ^= s << 8; h ^= s >> 56;
111 s = tab[b >> 12 & 0xF]; l ^= s << 12; h ^= s >> 52;
112 s = tab[b >> 16 & 0xF]; l ^= s << 16; h ^= s >> 48;
113 s = tab[b >> 20 & 0xF]; l ^= s << 20; h ^= s >> 44;
114 s = tab[b >> 24 & 0xF]; l ^= s << 24; h ^= s >> 40;
115 s = tab[b >> 28 & 0xF]; l ^= s << 28; h ^= s >> 36;
116 s = tab[b >> 32 & 0xF]; l ^= s << 32; h ^= s >> 32;
117 s = tab[b >> 36 & 0xF]; l ^= s << 36; h ^= s >> 28;
118 s = tab[b >> 40 & 0xF]; l ^= s << 40; h ^= s >> 24;
119 s = tab[b >> 44 & 0xF]; l ^= s << 44; h ^= s >> 20;
120 s = tab[b >> 48 & 0xF]; l ^= s << 48; h ^= s >> 16;
121 s = tab[b >> 52 & 0xF]; l ^= s << 52; h ^= s >> 12;
122 s = tab[b >> 56 & 0xF]; l ^= s << 56; h ^= s >> 8;
123 s = tab[b >> 60 ]; l ^= s << 60; h ^= s >> 4;
124
125 /* compensate for the top three bits of a */
126
127 if (top3b & 01) { l ^= b << 61; h ^= b >> 3; }
128 if (top3b & 02) { l ^= b << 62; h ^= b >> 2; }
129 if (top3b & 04) { l ^= b << 63; h ^= b >> 1; }
130
131 *rh = h; *rl = l;
132 }
133 #endif
134
135 /* Compute xor-multiply of two binary polynomials (a1, a0) x (b1, b0)
136 * result is a binary polynomial in 4 mp_digits r[4].
137 * The caller MUST ensure that r has the right amount of space allocated.
138 */
139 void
s_bmul_2x2(mp_digit * r,const mp_digit a1,const mp_digit a0,const mp_digit b1,const mp_digit b0)140 s_bmul_2x2(mp_digit *r, const mp_digit a1, const mp_digit a0, const mp_digit b1,
141 const mp_digit b0)
142 {
143 mp_digit m1, m0;
144 /* r[3] = h1, r[2] = h0; r[1] = l1; r[0] = l0 */
145 s_bmul_1x1(r+3, r+2, a1, b1);
146 s_bmul_1x1(r+1, r, a0, b0);
147 s_bmul_1x1(&m1, &m0, a0 ^ a1, b0 ^ b1);
148 /* Correction on m1 ^= l1 ^ h1; m0 ^= l0 ^ h0; */
149 r[2] ^= m1 ^ r[1] ^ r[3]; /* h0 ^= m1 ^ l1 ^ h1; */
150 r[1] = r[3] ^ r[2] ^ r[0] ^ m1 ^ m0; /* l1 ^= l0 ^ h0 ^ m0; */
151 }
152
153 /* Compute xor-multiply of two binary polynomials (a2, a1, a0) x (b2, b1, b0)
154 * result is a binary polynomial in 6 mp_digits r[6].
155 * The caller MUST ensure that r has the right amount of space allocated.
156 */
157 void
s_bmul_3x3(mp_digit * r,const mp_digit a2,const mp_digit a1,const mp_digit a0,const mp_digit b2,const mp_digit b1,const mp_digit b0)158 s_bmul_3x3(mp_digit *r, const mp_digit a2, const mp_digit a1, const mp_digit a0,
159 const mp_digit b2, const mp_digit b1, const mp_digit b0)
160 {
161 mp_digit zm[4];
162
163 s_bmul_1x1(r+5, r+4, a2, b2); /* fill top 2 words */
164 s_bmul_2x2(zm, a1, a2^a0, b1, b2^b0); /* fill middle 4 words */
165 s_bmul_2x2(r, a1, a0, b1, b0); /* fill bottom 4 words */
166
167 zm[3] ^= r[3];
168 zm[2] ^= r[2];
169 zm[1] ^= r[1] ^ r[5];
170 zm[0] ^= r[0] ^ r[4];
171
172 r[5] ^= zm[3];
173 r[4] ^= zm[2];
174 r[3] ^= zm[1];
175 r[2] ^= zm[0];
176 }
177
178 /* Compute xor-multiply of two binary polynomials (a3, a2, a1, a0) x (b3, b2, b1, b0)
179 * result is a binary polynomial in 8 mp_digits r[8].
180 * The caller MUST ensure that r has the right amount of space allocated.
181 */
s_bmul_4x4(mp_digit * r,const mp_digit a3,const mp_digit a2,const mp_digit a1,const mp_digit a0,const mp_digit b3,const mp_digit b2,const mp_digit b1,const mp_digit b0)182 void s_bmul_4x4(mp_digit *r, const mp_digit a3, const mp_digit a2, const mp_digit a1,
183 const mp_digit a0, const mp_digit b3, const mp_digit b2, const mp_digit b1,
184 const mp_digit b0)
185 {
186 mp_digit zm[4];
187
188 s_bmul_2x2(r+4, a3, a2, b3, b2); /* fill top 4 words */
189 s_bmul_2x2(zm, a3^a1, a2^a0, b3^b1, b2^b0); /* fill middle 4 words */
190 s_bmul_2x2(r, a1, a0, b1, b0); /* fill bottom 4 words */
191
192 zm[3] ^= r[3] ^ r[7];
193 zm[2] ^= r[2] ^ r[6];
194 zm[1] ^= r[1] ^ r[5];
195 zm[0] ^= r[0] ^ r[4];
196
197 r[5] ^= zm[3];
198 r[4] ^= zm[2];
199 r[3] ^= zm[1];
200 r[2] ^= zm[0];
201 }
202
203 /* Compute addition of two binary polynomials a and b,
204 * store result in c; c could be a or b, a and b could be equal;
205 * c is the bitwise XOR of a and b.
206 */
207 mp_err
mp_badd(const mp_int * a,const mp_int * b,mp_int * c)208 mp_badd(const mp_int *a, const mp_int *b, mp_int *c)
209 {
210 mp_digit *pa, *pb, *pc;
211 mp_size ix;
212 mp_size used_pa, used_pb;
213 mp_err res = MP_OKAY;
214
215 /* Add all digits up to the precision of b. If b had more
216 * precision than a initially, swap a, b first
217 */
218 if (MP_USED(a) >= MP_USED(b)) {
219 pa = MP_DIGITS(a);
220 pb = MP_DIGITS(b);
221 used_pa = MP_USED(a);
222 used_pb = MP_USED(b);
223 } else {
224 pa = MP_DIGITS(b);
225 pb = MP_DIGITS(a);
226 used_pa = MP_USED(b);
227 used_pb = MP_USED(a);
228 }
229
230 /* Make sure c has enough precision for the output value */
231 MP_CHECKOK( s_mp_pad(c, used_pa) );
232
233 /* Do word-by-word xor */
234 pc = MP_DIGITS(c);
235 for (ix = 0; ix < used_pb; ix++) {
236 (*pc++) = (*pa++) ^ (*pb++);
237 }
238
239 /* Finish the rest of digits until we're actually done */
240 for (; ix < used_pa; ++ix) {
241 *pc++ = *pa++;
242 }
243
244 MP_USED(c) = used_pa;
245 MP_SIGN(c) = ZPOS;
246 s_mp_clamp(c);
247
248 CLEANUP:
249 return res;
250 }
251
252 #define s_mp_div2(a) MP_CHECKOK( mpl_rsh((a), (a), 1) );
253
254 /* Compute binary polynomial multiply d = a * b */
255 static void
s_bmul_d(const mp_digit * a,mp_size a_len,mp_digit b,mp_digit * d)256 s_bmul_d(const mp_digit *a, mp_size a_len, mp_digit b, mp_digit *d)
257 {
258 mp_digit a_i, a0b0, a1b1, carry = 0;
259 while (a_len--) {
260 a_i = *a++;
261 s_bmul_1x1(&a1b1, &a0b0, a_i, b);
262 *d++ = a0b0 ^ carry;
263 carry = a1b1;
264 }
265 *d = carry;
266 }
267
268 /* Compute binary polynomial xor multiply accumulate d ^= a * b */
269 static void
s_bmul_d_add(const mp_digit * a,mp_size a_len,mp_digit b,mp_digit * d)270 s_bmul_d_add(const mp_digit *a, mp_size a_len, mp_digit b, mp_digit *d)
271 {
272 mp_digit a_i, a0b0, a1b1, carry = 0;
273 while (a_len--) {
274 a_i = *a++;
275 s_bmul_1x1(&a1b1, &a0b0, a_i, b);
276 *d++ ^= a0b0 ^ carry;
277 carry = a1b1;
278 }
279 *d ^= carry;
280 }
281
282 /* Compute binary polynomial xor multiply c = a * b.
283 * All parameters may be identical.
284 */
285 mp_err
mp_bmul(const mp_int * a,const mp_int * b,mp_int * c)286 mp_bmul(const mp_int *a, const mp_int *b, mp_int *c)
287 {
288 mp_digit *pb, b_i;
289 mp_int tmp;
290 mp_size ib, a_used, b_used;
291 mp_err res = MP_OKAY;
292
293 MP_DIGITS(&tmp) = 0;
294
295 ARGCHK(a != NULL && b != NULL && c != NULL, MP_BADARG);
296
297 if (a == c) {
298 MP_CHECKOK( mp_init_copy(&tmp, a) );
299 if (a == b)
300 b = &tmp;
301 a = &tmp;
302 } else if (b == c) {
303 MP_CHECKOK( mp_init_copy(&tmp, b) );
304 b = &tmp;
305 }
306
307 if (MP_USED(a) < MP_USED(b)) {
308 const mp_int *xch = b; /* switch a and b if b longer */
309 b = a;
310 a = xch;
311 }
312
313 MP_USED(c) = 1; MP_DIGIT(c, 0) = 0;
314 MP_CHECKOK( s_mp_pad(c, USED(a) + USED(b)) );
315
316 pb = MP_DIGITS(b);
317 s_bmul_d(MP_DIGITS(a), MP_USED(a), *pb++, MP_DIGITS(c));
318
319 /* Outer loop: Digits of b */
320 a_used = MP_USED(a);
321 b_used = MP_USED(b);
322 MP_USED(c) = a_used + b_used;
323 for (ib = 1; ib < b_used; ib++) {
324 b_i = *pb++;
325
326 /* Inner product: Digits of a */
327 if (b_i)
328 s_bmul_d_add(MP_DIGITS(a), a_used, b_i, MP_DIGITS(c) + ib);
329 else
330 MP_DIGIT(c, ib + a_used) = b_i;
331 }
332
333 s_mp_clamp(c);
334
335 SIGN(c) = ZPOS;
336
337 CLEANUP:
338 mp_clear(&tmp);
339 return res;
340 }
341
342
343 /* Compute modular reduction of a and store result in r.
344 * r could be a.
345 * For modular arithmetic, the irreducible polynomial f(t) is represented
346 * as an array of int[], where f(t) is of the form:
347 * f(t) = t^p[0] + t^p[1] + ... + t^p[k]
348 * where m = p[0] > p[1] > ... > p[k] = 0.
349 */
350 mp_err
mp_bmod(const mp_int * a,const unsigned int p[],mp_int * r)351 mp_bmod(const mp_int *a, const unsigned int p[], mp_int *r)
352 {
353 int j, k;
354 int n, dN, d0, d1;
355 mp_digit zz, *z, tmp;
356 mp_size used;
357 mp_err res = MP_OKAY;
358
359 /* The algorithm does the reduction in place in r,
360 * if a != r, copy a into r first so reduction can be done in r
361 */
362 if (a != r) {
363 MP_CHECKOK( mp_copy(a, r) );
364 }
365 z = MP_DIGITS(r);
366
367 /* start reduction */
368 dN = p[0] / MP_DIGIT_BITS;
369 used = MP_USED(r);
370
371 for (j = used - 1; j > dN;) {
372
373 zz = z[j];
374 if (zz == 0) {
375 j--; continue;
376 }
377 z[j] = 0;
378
379 for (k = 1; p[k] > 0; k++) {
380 /* reducing component t^p[k] */
381 n = p[0] - p[k];
382 d0 = n % MP_DIGIT_BITS;
383 d1 = MP_DIGIT_BITS - d0;
384 n /= MP_DIGIT_BITS;
385 z[j-n] ^= (zz>>d0);
386 if (d0)
387 z[j-n-1] ^= (zz<<d1);
388 }
389
390 /* reducing component t^0 */
391 n = dN;
392 d0 = p[0] % MP_DIGIT_BITS;
393 d1 = MP_DIGIT_BITS - d0;
394 z[j-n] ^= (zz >> d0);
395 if (d0)
396 z[j-n-1] ^= (zz << d1);
397
398 }
399
400 /* final round of reduction */
401 while (j == dN) {
402
403 d0 = p[0] % MP_DIGIT_BITS;
404 zz = z[dN] >> d0;
405 if (zz == 0) break;
406 d1 = MP_DIGIT_BITS - d0;
407
408 /* clear up the top d1 bits */
409 if (d0) z[dN] = (z[dN] << d1) >> d1;
410 *z ^= zz; /* reduction t^0 component */
411
412 for (k = 1; p[k] > 0; k++) {
413 /* reducing component t^p[k]*/
414 n = p[k] / MP_DIGIT_BITS;
415 d0 = p[k] % MP_DIGIT_BITS;
416 d1 = MP_DIGIT_BITS - d0;
417 z[n] ^= (zz << d0);
418 tmp = zz >> d1;
419 if (d0 && tmp)
420 z[n+1] ^= tmp;
421 }
422 }
423
424 s_mp_clamp(r);
425 CLEANUP:
426 return res;
427 }
428
429 /* Compute the product of two polynomials a and b, reduce modulo p,
430 * Store the result in r. r could be a or b; a could be b.
431 */
432 mp_err
mp_bmulmod(const mp_int * a,const mp_int * b,const unsigned int p[],mp_int * r)433 mp_bmulmod(const mp_int *a, const mp_int *b, const unsigned int p[], mp_int *r)
434 {
435 mp_err res;
436
437 if (a == b) return mp_bsqrmod(a, p, r);
438 if ((res = mp_bmul(a, b, r) ) != MP_OKAY)
439 return res;
440 return mp_bmod(r, p, r);
441 }
442
443 /* Compute binary polynomial squaring c = a*a mod p .
444 * Parameter r and a can be identical.
445 */
446
447 mp_err
mp_bsqrmod(const mp_int * a,const unsigned int p[],mp_int * r)448 mp_bsqrmod(const mp_int *a, const unsigned int p[], mp_int *r)
449 {
450 mp_digit *pa, *pr, a_i;
451 mp_int tmp;
452 mp_size ia, a_used;
453 mp_err res;
454
455 ARGCHK(a != NULL && r != NULL, MP_BADARG);
456 MP_DIGITS(&tmp) = 0;
457
458 if (a == r) {
459 MP_CHECKOK( mp_init_copy(&tmp, a) );
460 a = &tmp;
461 }
462
463 MP_USED(r) = 1; MP_DIGIT(r, 0) = 0;
464 MP_CHECKOK( s_mp_pad(r, 2*USED(a)) );
465
466 pa = MP_DIGITS(a);
467 pr = MP_DIGITS(r);
468 a_used = MP_USED(a);
469 MP_USED(r) = 2 * a_used;
470
471 for (ia = 0; ia < a_used; ia++) {
472 a_i = *pa++;
473 *pr++ = gf2m_SQR0(a_i);
474 *pr++ = gf2m_SQR1(a_i);
475 }
476
477 MP_CHECKOK( mp_bmod(r, p, r) );
478 s_mp_clamp(r);
479 SIGN(r) = ZPOS;
480
481 CLEANUP:
482 mp_clear(&tmp);
483 return res;
484 }
485
486 /* Compute binary polynomial y/x mod p, y divided by x, reduce modulo p.
487 * Store the result in r. r could be x or y, and x could equal y.
488 * Uses algorithm Modular_Division_GF(2^m) from
489 * Chang-Shantz, S. "From Euclid's GCD to Montgomery Multiplication to
490 * the Great Divide".
491 */
492 int
mp_bdivmod(const mp_int * y,const mp_int * x,const mp_int * pp,const unsigned int p[],mp_int * r)493 mp_bdivmod(const mp_int *y, const mp_int *x, const mp_int *pp,
494 const unsigned int p[], mp_int *r)
495 {
496 mp_int aa, bb, uu;
497 mp_int *a, *b, *u, *v;
498 mp_err res = MP_OKAY;
499
500 MP_DIGITS(&aa) = 0;
501 MP_DIGITS(&bb) = 0;
502 MP_DIGITS(&uu) = 0;
503
504 MP_CHECKOK( mp_init_copy(&aa, x) );
505 MP_CHECKOK( mp_init_copy(&uu, y) );
506 MP_CHECKOK( mp_init_copy(&bb, pp) );
507 MP_CHECKOK( s_mp_pad(r, USED(pp)) );
508 MP_USED(r) = 1; MP_DIGIT(r, 0) = 0;
509
510 a = &aa; b= &bb; u=&uu; v=r;
511 /* reduce x and y mod p */
512 MP_CHECKOK( mp_bmod(a, p, a) );
513 MP_CHECKOK( mp_bmod(u, p, u) );
514
515 while (!mp_isodd(a)) {
516 s_mp_div2(a);
517 if (mp_isodd(u)) {
518 MP_CHECKOK( mp_badd(u, pp, u) );
519 }
520 s_mp_div2(u);
521 }
522
523 do {
524 if (mp_cmp_mag(b, a) > 0) {
525 MP_CHECKOK( mp_badd(b, a, b) );
526 MP_CHECKOK( mp_badd(v, u, v) );
527 do {
528 s_mp_div2(b);
529 if (mp_isodd(v)) {
530 MP_CHECKOK( mp_badd(v, pp, v) );
531 }
532 s_mp_div2(v);
533 } while (!mp_isodd(b));
534 }
535 else if ((MP_DIGIT(a,0) == 1) && (MP_USED(a) == 1))
536 break;
537 else {
538 MP_CHECKOK( mp_badd(a, b, a) );
539 MP_CHECKOK( mp_badd(u, v, u) );
540 do {
541 s_mp_div2(a);
542 if (mp_isodd(u)) {
543 MP_CHECKOK( mp_badd(u, pp, u) );
544 }
545 s_mp_div2(u);
546 } while (!mp_isodd(a));
547 }
548 } while (1);
549
550 MP_CHECKOK( mp_copy(u, r) );
551
552 CLEANUP:
553 /* XXX this appears to be a memory leak in the NSS code */
554 mp_clear(&aa);
555 mp_clear(&bb);
556 mp_clear(&uu);
557 return res;
558
559 }
560
561 /* Convert the bit-string representation of a polynomial a into an array
562 * of integers corresponding to the bits with non-zero coefficient.
563 * Up to max elements of the array will be filled. Return value is total
564 * number of coefficients that would be extracted if array was large enough.
565 */
566 int
mp_bpoly2arr(const mp_int * a,unsigned int p[],int max)567 mp_bpoly2arr(const mp_int *a, unsigned int p[], int max)
568 {
569 int i, j, k;
570 mp_digit top_bit, mask;
571
572 top_bit = 1;
573 top_bit <<= MP_DIGIT_BIT - 1;
574
575 for (k = 0; k < max; k++) p[k] = 0;
576 k = 0;
577
578 for (i = MP_USED(a) - 1; i >= 0; i--) {
579 mask = top_bit;
580 for (j = MP_DIGIT_BIT - 1; j >= 0; j--) {
581 if (MP_DIGITS(a)[i] & mask) {
582 if (k < max) p[k] = MP_DIGIT_BIT * i + j;
583 k++;
584 }
585 mask >>= 1;
586 }
587 }
588
589 return k;
590 }
591
592 /* Convert the coefficient array representation of a polynomial to a
593 * bit-string. The array must be terminated by 0.
594 */
595 mp_err
mp_barr2poly(const unsigned int p[],mp_int * a)596 mp_barr2poly(const unsigned int p[], mp_int *a)
597 {
598
599 mp_err res = MP_OKAY;
600 int i;
601
602 mp_zero(a);
603 for (i = 0; p[i] > 0; i++) {
604 MP_CHECKOK( mpl_set_bit(a, p[i], 1) );
605 }
606 MP_CHECKOK( mpl_set_bit(a, 0, 1) );
607
608 CLEANUP:
609 return res;
610 }
611