xref: /illumos-gate/usr/src/common/mpi/mp_gf2m.c (revision f9fbec18)
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 #pragma ident	"%Z%%M%	%I%	%E% SMI"
47 
48 #include "mp_gf2m.h"
49 #include "mp_gf2m-priv.h"
50 #include "mplogic.h"
51 #include "mpi-priv.h"
52 
53 const mp_digit mp_gf2m_sqr_tb[16] =
54 {
55       0,     1,     4,     5,    16,    17,    20,    21,
56      64,    65,    68,    69,    80,    81,    84,    85
57 };
58 
59 /* Multiply two binary polynomials mp_digits a, b.
60  * Result is a polynomial with degree < 2 * MP_DIGIT_BITS - 1.
61  * Output in two mp_digits rh, rl.
62  */
63 #if MP_DIGIT_BITS == 32
64 void
s_bmul_1x1(mp_digit * rh,mp_digit * rl,const mp_digit a,const mp_digit b)65 s_bmul_1x1(mp_digit *rh, mp_digit *rl, const mp_digit a, const mp_digit b)
66 {
67     register mp_digit h, l, s;
68     mp_digit tab[8], top2b = a >> 30;
69     register mp_digit a1, a2, a4;
70 
71     a1 = a & (0x3FFFFFFF); a2 = a1 << 1; a4 = a2 << 1;
72 
73     tab[0] =  0; tab[1] = a1;    tab[2] = a2;    tab[3] = a1^a2;
74     tab[4] = a4; tab[5] = a1^a4; tab[6] = a2^a4; tab[7] = a1^a2^a4;
75 
76     s = tab[b       & 0x7]; l  = s;
77     s = tab[b >>  3 & 0x7]; l ^= s <<  3; h  = s >> 29;
78     s = tab[b >>  6 & 0x7]; l ^= s <<  6; h ^= s >> 26;
79     s = tab[b >>  9 & 0x7]; l ^= s <<  9; h ^= s >> 23;
80     s = tab[b >> 12 & 0x7]; l ^= s << 12; h ^= s >> 20;
81     s = tab[b >> 15 & 0x7]; l ^= s << 15; h ^= s >> 17;
82     s = tab[b >> 18 & 0x7]; l ^= s << 18; h ^= s >> 14;
83     s = tab[b >> 21 & 0x7]; l ^= s << 21; h ^= s >> 11;
84     s = tab[b >> 24 & 0x7]; l ^= s << 24; h ^= s >>  8;
85     s = tab[b >> 27 & 0x7]; l ^= s << 27; h ^= s >>  5;
86     s = tab[b >> 30      ]; l ^= s << 30; h ^= s >>  2;
87 
88     /* compensate for the top two bits of a */
89 
90     if (top2b & 01) { l ^= b << 30; h ^= b >> 2; }
91     if (top2b & 02) { l ^= b << 31; h ^= b >> 1; }
92 
93     *rh = h; *rl = l;
94 }
95 #else
96 void
s_bmul_1x1(mp_digit * rh,mp_digit * rl,const mp_digit a,const mp_digit b)97 s_bmul_1x1(mp_digit *rh, mp_digit *rl, const mp_digit a, const mp_digit b)
98 {
99     register mp_digit h, l, s;
100     mp_digit tab[16], top3b = a >> 61;
101     register mp_digit a1, a2, a4, a8;
102 
103     a1 = a & (0x1FFFFFFFFFFFFFFFULL); a2 = a1 << 1;
104     a4 = a2 << 1; a8 = a4 << 1;
105     tab[ 0] = 0;     tab[ 1] = a1;       tab[ 2] = a2;       tab[ 3] = a1^a2;
106     tab[ 4] = a4;    tab[ 5] = a1^a4;    tab[ 6] = a2^a4;    tab[ 7] = a1^a2^a4;
107     tab[ 8] = a8;    tab[ 9] = a1^a8;    tab[10] = a2^a8;    tab[11] = a1^a2^a8;
108     tab[12] = a4^a8; tab[13] = a1^a4^a8; tab[14] = a2^a4^a8; tab[15] = a1^a2^a4^a8;
109 
110     s = tab[b       & 0xF]; l  = s;
111     s = tab[b >>  4 & 0xF]; l ^= s <<  4; h  = s >> 60;
112     s = tab[b >>  8 & 0xF]; l ^= s <<  8; h ^= s >> 56;
113     s = tab[b >> 12 & 0xF]; l ^= s << 12; h ^= s >> 52;
114     s = tab[b >> 16 & 0xF]; l ^= s << 16; h ^= s >> 48;
115     s = tab[b >> 20 & 0xF]; l ^= s << 20; h ^= s >> 44;
116     s = tab[b >> 24 & 0xF]; l ^= s << 24; h ^= s >> 40;
117     s = tab[b >> 28 & 0xF]; l ^= s << 28; h ^= s >> 36;
118     s = tab[b >> 32 & 0xF]; l ^= s << 32; h ^= s >> 32;
119     s = tab[b >> 36 & 0xF]; l ^= s << 36; h ^= s >> 28;
120     s = tab[b >> 40 & 0xF]; l ^= s << 40; h ^= s >> 24;
121     s = tab[b >> 44 & 0xF]; l ^= s << 44; h ^= s >> 20;
122     s = tab[b >> 48 & 0xF]; l ^= s << 48; h ^= s >> 16;
123     s = tab[b >> 52 & 0xF]; l ^= s << 52; h ^= s >> 12;
124     s = tab[b >> 56 & 0xF]; l ^= s << 56; h ^= s >>  8;
125     s = tab[b >> 60      ]; l ^= s << 60; h ^= s >>  4;
126 
127     /* compensate for the top three bits of a */
128 
129     if (top3b & 01) { l ^= b << 61; h ^= b >> 3; }
130     if (top3b & 02) { l ^= b << 62; h ^= b >> 2; }
131     if (top3b & 04) { l ^= b << 63; h ^= b >> 1; }
132 
133     *rh = h; *rl = l;
134 }
135 #endif
136 
137 /* Compute xor-multiply of two binary polynomials  (a1, a0) x (b1, b0)
138  * result is a binary polynomial in 4 mp_digits r[4].
139  * The caller MUST ensure that r has the right amount of space allocated.
140  */
141 void
s_bmul_2x2(mp_digit * r,const mp_digit a1,const mp_digit a0,const mp_digit b1,const mp_digit b0)142 s_bmul_2x2(mp_digit *r, const mp_digit a1, const mp_digit a0, const mp_digit b1,
143            const mp_digit b0)
144 {
145     mp_digit m1, m0;
146     /* r[3] = h1, r[2] = h0; r[1] = l1; r[0] = l0 */
147     s_bmul_1x1(r+3, r+2, a1, b1);
148     s_bmul_1x1(r+1, r, a0, b0);
149     s_bmul_1x1(&m1, &m0, a0 ^ a1, b0 ^ b1);
150     /* Correction on m1 ^= l1 ^ h1; m0 ^= l0 ^ h0; */
151     r[2] ^= m1 ^ r[1] ^ r[3];  /* h0 ^= m1 ^ l1 ^ h1; */
152     r[1]  = r[3] ^ r[2] ^ r[0] ^ m1 ^ m0;  /* l1 ^= l0 ^ h0 ^ m0; */
153 }
154 
155 /* Compute xor-multiply of two binary polynomials  (a2, a1, a0) x (b2, b1, b0)
156  * result is a binary polynomial in 6 mp_digits r[6].
157  * The caller MUST ensure that r has the right amount of space allocated.
158  */
159 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)160 s_bmul_3x3(mp_digit *r, const mp_digit a2, const mp_digit a1, const mp_digit a0,
161 	const mp_digit b2, const mp_digit b1, const mp_digit b0)
162 {
163 	mp_digit zm[4];
164 
165 	s_bmul_1x1(r+5, r+4, a2, b2);         /* fill top 2 words */
166 	s_bmul_2x2(zm, a1, a2^a0, b1, b2^b0); /* fill middle 4 words */
167 	s_bmul_2x2(r, a1, a0, b1, b0);        /* fill bottom 4 words */
168 
169 	zm[3] ^= r[3];
170 	zm[2] ^= r[2];
171 	zm[1] ^= r[1] ^ r[5];
172 	zm[0] ^= r[0] ^ r[4];
173 
174 	r[5]  ^= zm[3];
175 	r[4]  ^= zm[2];
176 	r[3]  ^= zm[1];
177 	r[2]  ^= zm[0];
178 }
179 
180 /* Compute xor-multiply of two binary polynomials  (a3, a2, a1, a0) x (b3, b2, b1, b0)
181  * result is a binary polynomial in 8 mp_digits r[8].
182  * The caller MUST ensure that r has the right amount of space allocated.
183  */
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)184 void s_bmul_4x4(mp_digit *r, const mp_digit a3, const mp_digit a2, const mp_digit a1,
185 	const mp_digit a0, const mp_digit b3, const mp_digit b2, const mp_digit b1,
186 	const mp_digit b0)
187 {
188 	mp_digit zm[4];
189 
190 	s_bmul_2x2(r+4, a3, a2, b3, b2);            /* fill top 4 words */
191 	s_bmul_2x2(zm, a3^a1, a2^a0, b3^b1, b2^b0); /* fill middle 4 words */
192 	s_bmul_2x2(r, a1, a0, b1, b0);              /* fill bottom 4 words */
193 
194 	zm[3] ^= r[3] ^ r[7];
195 	zm[2] ^= r[2] ^ r[6];
196 	zm[1] ^= r[1] ^ r[5];
197 	zm[0] ^= r[0] ^ r[4];
198 
199 	r[5]  ^= zm[3];
200 	r[4]  ^= zm[2];
201 	r[3]  ^= zm[1];
202 	r[2]  ^= zm[0];
203 }
204 
205 /* Compute addition of two binary polynomials a and b,
206  * store result in c; c could be a or b, a and b could be equal;
207  * c is the bitwise XOR of a and b.
208  */
209 mp_err
mp_badd(const mp_int * a,const mp_int * b,mp_int * c)210 mp_badd(const mp_int *a, const mp_int *b, mp_int *c)
211 {
212     mp_digit *pa, *pb, *pc;
213     mp_size ix;
214     mp_size used_pa, used_pb;
215     mp_err res = MP_OKAY;
216 
217     /* Add all digits up to the precision of b.  If b had more
218      * precision than a initially, swap a, b first
219      */
220     if (MP_USED(a) >= MP_USED(b)) {
221         pa = MP_DIGITS(a);
222         pb = MP_DIGITS(b);
223         used_pa = MP_USED(a);
224         used_pb = MP_USED(b);
225     } else {
226         pa = MP_DIGITS(b);
227         pb = MP_DIGITS(a);
228         used_pa = MP_USED(b);
229         used_pb = MP_USED(a);
230     }
231 
232     /* Make sure c has enough precision for the output value */
233     MP_CHECKOK( s_mp_pad(c, used_pa) );
234 
235     /* Do word-by-word xor */
236     pc = MP_DIGITS(c);
237     for (ix = 0; ix < used_pb; ix++) {
238         (*pc++) = (*pa++) ^ (*pb++);
239     }
240 
241     /* Finish the rest of digits until we're actually done */
242     for (; ix < used_pa; ++ix) {
243         *pc++ = *pa++;
244     }
245 
246     MP_USED(c) = used_pa;
247     MP_SIGN(c) = ZPOS;
248     s_mp_clamp(c);
249 
250 CLEANUP:
251     return res;
252 }
253 
254 #define s_mp_div2(a) MP_CHECKOK( mpl_rsh((a), (a), 1) );
255 
256 /* Compute binary polynomial multiply d = a * b */
257 static void
s_bmul_d(const mp_digit * a,mp_size a_len,mp_digit b,mp_digit * d)258 s_bmul_d(const mp_digit *a, mp_size a_len, mp_digit b, mp_digit *d)
259 {
260     mp_digit a_i, a0b0, a1b1, carry = 0;
261     while (a_len--) {
262         a_i = *a++;
263         s_bmul_1x1(&a1b1, &a0b0, a_i, b);
264         *d++ = a0b0 ^ carry;
265         carry = a1b1;
266     }
267     *d = carry;
268 }
269 
270 /* Compute binary polynomial xor multiply accumulate d ^= a * b */
271 static void
s_bmul_d_add(const mp_digit * a,mp_size a_len,mp_digit b,mp_digit * d)272 s_bmul_d_add(const mp_digit *a, mp_size a_len, mp_digit b, mp_digit *d)
273 {
274     mp_digit a_i, a0b0, a1b1, carry = 0;
275     while (a_len--) {
276         a_i = *a++;
277         s_bmul_1x1(&a1b1, &a0b0, a_i, b);
278         *d++ ^= a0b0 ^ carry;
279         carry = a1b1;
280     }
281     *d ^= carry;
282 }
283 
284 /* Compute binary polynomial xor multiply c = a * b.
285  * All parameters may be identical.
286  */
287 mp_err
mp_bmul(const mp_int * a,const mp_int * b,mp_int * c)288 mp_bmul(const mp_int *a, const mp_int *b, mp_int *c)
289 {
290     mp_digit *pb, b_i;
291     mp_int tmp;
292     mp_size ib, a_used, b_used;
293     mp_err res = MP_OKAY;
294 
295     MP_DIGITS(&tmp) = 0;
296 
297     ARGCHK(a != NULL && b != NULL && c != NULL, MP_BADARG);
298 
299     if (a == c) {
300         MP_CHECKOK( mp_init_copy(&tmp, a) );
301         if (a == b)
302             b = &tmp;
303         a = &tmp;
304     } else if (b == c) {
305         MP_CHECKOK( mp_init_copy(&tmp, b) );
306         b = &tmp;
307     }
308 
309     if (MP_USED(a) < MP_USED(b)) {
310         const mp_int *xch = b;      /* switch a and b if b longer */
311         b = a;
312         a = xch;
313     }
314 
315     MP_USED(c) = 1; MP_DIGIT(c, 0) = 0;
316     MP_CHECKOK( s_mp_pad(c, USED(a) + USED(b)) );
317 
318     pb = MP_DIGITS(b);
319     s_bmul_d(MP_DIGITS(a), MP_USED(a), *pb++, MP_DIGITS(c));
320 
321     /* Outer loop:  Digits of b */
322     a_used = MP_USED(a);
323     b_used = MP_USED(b);
324 	MP_USED(c) = a_used + b_used;
325     for (ib = 1; ib < b_used; ib++) {
326         b_i = *pb++;
327 
328         /* Inner product:  Digits of a */
329         if (b_i)
330             s_bmul_d_add(MP_DIGITS(a), a_used, b_i, MP_DIGITS(c) + ib);
331         else
332             MP_DIGIT(c, ib + a_used) = b_i;
333     }
334 
335     s_mp_clamp(c);
336 
337     SIGN(c) = ZPOS;
338 
339 CLEANUP:
340     mp_clear(&tmp);
341     return res;
342 }
343 
344 
345 /* Compute modular reduction of a and store result in r.
346  * r could be a.
347  * For modular arithmetic, the irreducible polynomial f(t) is represented
348  * as an array of int[], where f(t) is of the form:
349  *     f(t) = t^p[0] + t^p[1] + ... + t^p[k]
350  * where m = p[0] > p[1] > ... > p[k] = 0.
351  */
352 mp_err
mp_bmod(const mp_int * a,const unsigned int p[],mp_int * r)353 mp_bmod(const mp_int *a, const unsigned int p[], mp_int *r)
354 {
355     int j, k;
356     int n, dN, d0, d1;
357     mp_digit zz, *z, tmp;
358     mp_size used;
359     mp_err res = MP_OKAY;
360 
361     /* The algorithm does the reduction in place in r,
362      * if a != r, copy a into r first so reduction can be done in r
363      */
364     if (a != r) {
365         MP_CHECKOK( mp_copy(a, r) );
366     }
367     z = MP_DIGITS(r);
368 
369     /* start reduction */
370     dN = p[0] / MP_DIGIT_BITS;
371     used = MP_USED(r);
372 
373     for (j = used - 1; j > dN;) {
374 
375         zz = z[j];
376         if (zz == 0) {
377             j--; continue;
378         }
379         z[j] = 0;
380 
381         for (k = 1; p[k] > 0; k++) {
382             /* reducing component t^p[k] */
383             n = p[0] - p[k];
384             d0 = n % MP_DIGIT_BITS;
385             d1 = MP_DIGIT_BITS - d0;
386             n /= MP_DIGIT_BITS;
387             z[j-n] ^= (zz>>d0);
388             if (d0)
389                 z[j-n-1] ^= (zz<<d1);
390         }
391 
392         /* reducing component t^0 */
393         n = dN;
394         d0 = p[0] % MP_DIGIT_BITS;
395         d1 = MP_DIGIT_BITS - d0;
396         z[j-n] ^= (zz >> d0);
397         if (d0)
398             z[j-n-1] ^= (zz << d1);
399 
400     }
401 
402     /* final round of reduction */
403     while (j == dN) {
404 
405         d0 = p[0] % MP_DIGIT_BITS;
406         zz = z[dN] >> d0;
407         if (zz == 0) break;
408         d1 = MP_DIGIT_BITS - d0;
409 
410         /* clear up the top d1 bits */
411         if (d0) z[dN] = (z[dN] << d1) >> d1;
412         *z ^= zz; /* reduction t^0 component */
413 
414         for (k = 1; p[k] > 0; k++) {
415             /* reducing component t^p[k]*/
416             n = p[k] / MP_DIGIT_BITS;
417             d0 = p[k] % MP_DIGIT_BITS;
418             d1 = MP_DIGIT_BITS - d0;
419             z[n] ^= (zz << d0);
420             tmp = zz >> d1;
421             if (d0 && tmp)
422                 z[n+1] ^= tmp;
423         }
424     }
425 
426     s_mp_clamp(r);
427 CLEANUP:
428     return res;
429 }
430 
431 /* Compute the product of two polynomials a and b, reduce modulo p,
432  * Store the result in r.  r could be a or b; a could be b.
433  */
434 mp_err
mp_bmulmod(const mp_int * a,const mp_int * b,const unsigned int p[],mp_int * r)435 mp_bmulmod(const mp_int *a, const mp_int *b, const unsigned int p[], mp_int *r)
436 {
437     mp_err res;
438 
439     if (a == b) return mp_bsqrmod(a, p, r);
440     if ((res = mp_bmul(a, b, r) ) != MP_OKAY)
441 	return res;
442     return mp_bmod(r, p, r);
443 }
444 
445 /* Compute binary polynomial squaring c = a*a mod p .
446  * Parameter r and a can be identical.
447  */
448 
449 mp_err
mp_bsqrmod(const mp_int * a,const unsigned int p[],mp_int * r)450 mp_bsqrmod(const mp_int *a, const unsigned int p[], mp_int *r)
451 {
452     mp_digit *pa, *pr, a_i;
453     mp_int tmp;
454     mp_size ia, a_used;
455     mp_err res;
456 
457     ARGCHK(a != NULL && r != NULL, MP_BADARG);
458     MP_DIGITS(&tmp) = 0;
459 
460     if (a == r) {
461         MP_CHECKOK( mp_init_copy(&tmp, a) );
462         a = &tmp;
463     }
464 
465     MP_USED(r) = 1; MP_DIGIT(r, 0) = 0;
466     MP_CHECKOK( s_mp_pad(r, 2*USED(a)) );
467 
468     pa = MP_DIGITS(a);
469     pr = MP_DIGITS(r);
470     a_used = MP_USED(a);
471 	MP_USED(r) = 2 * a_used;
472 
473     for (ia = 0; ia < a_used; ia++) {
474         a_i = *pa++;
475         *pr++ = gf2m_SQR0(a_i);
476         *pr++ = gf2m_SQR1(a_i);
477     }
478 
479     MP_CHECKOK( mp_bmod(r, p, r) );
480     s_mp_clamp(r);
481     SIGN(r) = ZPOS;
482 
483 CLEANUP:
484     mp_clear(&tmp);
485     return res;
486 }
487 
488 /* Compute binary polynomial y/x mod p, y divided by x, reduce modulo p.
489  * Store the result in r. r could be x or y, and x could equal y.
490  * Uses algorithm Modular_Division_GF(2^m) from
491  *     Chang-Shantz, S.  "From Euclid's GCD to Montgomery Multiplication to
492  *     the Great Divide".
493  */
494 int
mp_bdivmod(const mp_int * y,const mp_int * x,const mp_int * pp,const unsigned int p[],mp_int * r)495 mp_bdivmod(const mp_int *y, const mp_int *x, const mp_int *pp,
496     const unsigned int p[], mp_int *r)
497 {
498     mp_int aa, bb, uu;
499     mp_int *a, *b, *u, *v;
500     mp_err res = MP_OKAY;
501 
502     MP_DIGITS(&aa) = 0;
503     MP_DIGITS(&bb) = 0;
504     MP_DIGITS(&uu) = 0;
505 
506     MP_CHECKOK( mp_init_copy(&aa, x) );
507     MP_CHECKOK( mp_init_copy(&uu, y) );
508     MP_CHECKOK( mp_init_copy(&bb, pp) );
509     MP_CHECKOK( s_mp_pad(r, USED(pp)) );
510     MP_USED(r) = 1; MP_DIGIT(r, 0) = 0;
511 
512     a = &aa; b= &bb; u=&uu; v=r;
513     /* reduce x and y mod p */
514     MP_CHECKOK( mp_bmod(a, p, a) );
515     MP_CHECKOK( mp_bmod(u, p, u) );
516 
517     while (!mp_isodd(a)) {
518         s_mp_div2(a);
519         if (mp_isodd(u)) {
520             MP_CHECKOK( mp_badd(u, pp, u) );
521         }
522         s_mp_div2(u);
523     }
524 
525     do {
526         if (mp_cmp_mag(b, a) > 0) {
527             MP_CHECKOK( mp_badd(b, a, b) );
528             MP_CHECKOK( mp_badd(v, u, v) );
529             do {
530                 s_mp_div2(b);
531                 if (mp_isodd(v)) {
532                     MP_CHECKOK( mp_badd(v, pp, v) );
533                 }
534                 s_mp_div2(v);
535             } while (!mp_isodd(b));
536         }
537         else if ((MP_DIGIT(a,0) == 1) && (MP_USED(a) == 1))
538             break;
539         else {
540             MP_CHECKOK( mp_badd(a, b, a) );
541             MP_CHECKOK( mp_badd(u, v, u) );
542             do {
543                 s_mp_div2(a);
544                 if (mp_isodd(u)) {
545                     MP_CHECKOK( mp_badd(u, pp, u) );
546                 }
547                 s_mp_div2(u);
548             } while (!mp_isodd(a));
549         }
550     } while (1);
551 
552     MP_CHECKOK( mp_copy(u, r) );
553 
554 CLEANUP:
555     /* XXX this appears to be a memory leak in the NSS code */
556     mp_clear(&aa);
557     mp_clear(&bb);
558     mp_clear(&uu);
559     return res;
560 
561 }
562 
563 /* Convert the bit-string representation of a polynomial a into an array
564  * of integers corresponding to the bits with non-zero coefficient.
565  * Up to max elements of the array will be filled.  Return value is total
566  * number of coefficients that would be extracted if array was large enough.
567  */
568 int
mp_bpoly2arr(const mp_int * a,unsigned int p[],int max)569 mp_bpoly2arr(const mp_int *a, unsigned int p[], int max)
570 {
571     int i, j, k;
572     mp_digit top_bit, mask;
573 
574     top_bit = 1;
575     top_bit <<= MP_DIGIT_BIT - 1;
576 
577     for (k = 0; k < max; k++) p[k] = 0;
578     k = 0;
579 
580     for (i = MP_USED(a) - 1; i >= 0; i--) {
581         mask = top_bit;
582         for (j = MP_DIGIT_BIT - 1; j >= 0; j--) {
583             if (MP_DIGITS(a)[i] & mask) {
584                 if (k < max) p[k] = MP_DIGIT_BIT * i + j;
585                 k++;
586             }
587             mask >>= 1;
588         }
589     }
590 
591     return k;
592 }
593 
594 /* Convert the coefficient array representation of a polynomial to a
595  * bit-string.  The array must be terminated by 0.
596  */
597 mp_err
mp_barr2poly(const unsigned int p[],mp_int * a)598 mp_barr2poly(const unsigned int p[], mp_int *a)
599 {
600 
601     mp_err res = MP_OKAY;
602     int i;
603 
604     mp_zero(a);
605     for (i = 0; p[i] > 0; i++) {
606 	MP_CHECKOK( mpl_set_bit(a, p[i], 1) );
607     }
608     MP_CHECKOK( mpl_set_bit(a, 0, 1) );
609 
610 CLEANUP:
611     return res;
612 }
613