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1 /* Copyright (c) 2014, Intel Corporation.
2  *
3  * Permission to use, copy, modify, and/or distribute this software for any
4  * purpose with or without fee is hereby granted, provided that the above
5  * copyright notice and this permission notice appear in all copies.
6  *
7  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
8  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
9  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
10  * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
11  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
12  * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
13  * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
14 
15 /* Developers and authors:
16  * Shay Gueron (1, 2), and Vlad Krasnov (1)
17  * (1) Intel Corporation, Israel Development Center
18  * (2) University of Haifa
19  * Reference:
20  * S.Gueron and V.Krasnov, "Fast Prime Field Elliptic Curve Cryptography with
21  *                          256 Bit Primes" */
22 
23 #include <openssl/ec.h>
24 
25 #include <assert.h>
26 #include <stdint.h>
27 #include <string.h>
28 
29 #include <openssl/bn.h>
30 #include <openssl/crypto.h>
31 #include <openssl/err.h>
32 
33 #include "../bn/internal.h"
34 #include "../internal.h"
35 #include "internal.h"
36 #include "p256-x86_64.h"
37 
38 
39 #if !defined(OPENSSL_NO_ASM) && defined(OPENSSL_X86_64) && \
40     !defined(OPENSSL_SMALL)
41 
42 typedef P256_POINT_AFFINE PRECOMP256_ROW[64];
43 
44 /* One converted into the Montgomery domain */
45 static const BN_ULONG ONE[P256_LIMBS] = {
46     TOBN(0x00000000, 0x00000001), TOBN(0xffffffff, 0x00000000),
47     TOBN(0xffffffff, 0xffffffff), TOBN(0x00000000, 0xfffffffe),
48 };
49 
50 /* Precomputed tables for the default generator */
51 #include "p256-x86_64-table.h"
52 
53 /* Recode window to a signed digit, see util-64.c for details */
booth_recode_w5(unsigned in)54 static unsigned booth_recode_w5(unsigned in) {
55   unsigned s, d;
56 
57   s = ~((in >> 5) - 1);
58   d = (1 << 6) - in - 1;
59   d = (d & s) | (in & ~s);
60   d = (d >> 1) + (d & 1);
61 
62   return (d << 1) + (s & 1);
63 }
64 
booth_recode_w7(unsigned in)65 static unsigned booth_recode_w7(unsigned in) {
66   unsigned s, d;
67 
68   s = ~((in >> 7) - 1);
69   d = (1 << 8) - in - 1;
70   d = (d & s) | (in & ~s);
71   d = (d >> 1) + (d & 1);
72 
73   return (d << 1) + (s & 1);
74 }
75 
76 /* copy_conditional copies |src| to |dst| if |move| is one and leaves it as-is
77  * if |move| is zero.
78  *
79  * WARNING: this breaks the usual convention of constant-time functions
80  * returning masks. */
copy_conditional(BN_ULONG dst[P256_LIMBS],const BN_ULONG src[P256_LIMBS],BN_ULONG move)81 static void copy_conditional(BN_ULONG dst[P256_LIMBS],
82                              const BN_ULONG src[P256_LIMBS], BN_ULONG move) {
83   BN_ULONG mask1 = ((BN_ULONG)0) - move;
84   BN_ULONG mask2 = ~mask1;
85 
86   dst[0] = (src[0] & mask1) ^ (dst[0] & mask2);
87   dst[1] = (src[1] & mask1) ^ (dst[1] & mask2);
88   dst[2] = (src[2] & mask1) ^ (dst[2] & mask2);
89   dst[3] = (src[3] & mask1) ^ (dst[3] & mask2);
90   if (P256_LIMBS == 8) {
91     dst[4] = (src[4] & mask1) ^ (dst[4] & mask2);
92     dst[5] = (src[5] & mask1) ^ (dst[5] & mask2);
93     dst[6] = (src[6] & mask1) ^ (dst[6] & mask2);
94     dst[7] = (src[7] & mask1) ^ (dst[7] & mask2);
95   }
96 }
97 
98 /* is_not_zero returns one iff in != 0 and zero otherwise.
99  *
100  * WARNING: this breaks the usual convention of constant-time functions
101  * returning masks.
102  *
103  * (define-fun is_not_zero ((in (_ BitVec 64))) (_ BitVec 64)
104  *   (bvlshr (bvor in (bvsub #x0000000000000000 in)) #x000000000000003f)
105  * )
106  *
107  * (declare-fun x () (_ BitVec 64))
108  *
109  * (assert (and (= x #x0000000000000000) (= (is_not_zero x) #x0000000000000001)))
110  * (check-sat)
111  *
112  * (assert (and (not (= x #x0000000000000000)) (= (is_not_zero x) #x0000000000000000)))
113  * (check-sat)
114  * */
is_not_zero(BN_ULONG in)115 static BN_ULONG is_not_zero(BN_ULONG in) {
116   in |= (0 - in);
117   in >>= BN_BITS2 - 1;
118   return in;
119 }
120 
121 /* ecp_nistz256_mod_inverse_mont sets |r| to (|in| * 2^-256)^-1 * 2^256 mod p.
122  * That is, |r| is the modular inverse of |in| for input and output in the
123  * Montgomery domain. */
ecp_nistz256_mod_inverse_mont(BN_ULONG r[P256_LIMBS],const BN_ULONG in[P256_LIMBS])124 static void ecp_nistz256_mod_inverse_mont(BN_ULONG r[P256_LIMBS],
125                                           const BN_ULONG in[P256_LIMBS]) {
126   /* The poly is ffffffff 00000001 00000000 00000000 00000000 ffffffff ffffffff
127      ffffffff
128      We use FLT and used poly-2 as exponent */
129   BN_ULONG p2[P256_LIMBS];
130   BN_ULONG p4[P256_LIMBS];
131   BN_ULONG p8[P256_LIMBS];
132   BN_ULONG p16[P256_LIMBS];
133   BN_ULONG p32[P256_LIMBS];
134   BN_ULONG res[P256_LIMBS];
135   int i;
136 
137   ecp_nistz256_sqr_mont(res, in);
138   ecp_nistz256_mul_mont(p2, res, in); /* 3*p */
139 
140   ecp_nistz256_sqr_mont(res, p2);
141   ecp_nistz256_sqr_mont(res, res);
142   ecp_nistz256_mul_mont(p4, res, p2); /* f*p */
143 
144   ecp_nistz256_sqr_mont(res, p4);
145   ecp_nistz256_sqr_mont(res, res);
146   ecp_nistz256_sqr_mont(res, res);
147   ecp_nistz256_sqr_mont(res, res);
148   ecp_nistz256_mul_mont(p8, res, p4); /* ff*p */
149 
150   ecp_nistz256_sqr_mont(res, p8);
151   for (i = 0; i < 7; i++) {
152     ecp_nistz256_sqr_mont(res, res);
153   }
154   ecp_nistz256_mul_mont(p16, res, p8); /* ffff*p */
155 
156   ecp_nistz256_sqr_mont(res, p16);
157   for (i = 0; i < 15; i++) {
158     ecp_nistz256_sqr_mont(res, res);
159   }
160   ecp_nistz256_mul_mont(p32, res, p16); /* ffffffff*p */
161 
162   ecp_nistz256_sqr_mont(res, p32);
163   for (i = 0; i < 31; i++) {
164     ecp_nistz256_sqr_mont(res, res);
165   }
166   ecp_nistz256_mul_mont(res, res, in);
167 
168   for (i = 0; i < 32 * 4; i++) {
169     ecp_nistz256_sqr_mont(res, res);
170   }
171   ecp_nistz256_mul_mont(res, res, p32);
172 
173   for (i = 0; i < 32; i++) {
174     ecp_nistz256_sqr_mont(res, res);
175   }
176   ecp_nistz256_mul_mont(res, res, p32);
177 
178   for (i = 0; i < 16; i++) {
179     ecp_nistz256_sqr_mont(res, res);
180   }
181   ecp_nistz256_mul_mont(res, res, p16);
182 
183   for (i = 0; i < 8; i++) {
184     ecp_nistz256_sqr_mont(res, res);
185   }
186   ecp_nistz256_mul_mont(res, res, p8);
187 
188   ecp_nistz256_sqr_mont(res, res);
189   ecp_nistz256_sqr_mont(res, res);
190   ecp_nistz256_sqr_mont(res, res);
191   ecp_nistz256_sqr_mont(res, res);
192   ecp_nistz256_mul_mont(res, res, p4);
193 
194   ecp_nistz256_sqr_mont(res, res);
195   ecp_nistz256_sqr_mont(res, res);
196   ecp_nistz256_mul_mont(res, res, p2);
197 
198   ecp_nistz256_sqr_mont(res, res);
199   ecp_nistz256_sqr_mont(res, res);
200   ecp_nistz256_mul_mont(r, res, in);
201 }
202 
203 /* ecp_nistz256_bignum_to_field_elem copies the contents of |in| to |out| and
204  * returns one if it fits. Otherwise it returns zero. */
ecp_nistz256_bignum_to_field_elem(BN_ULONG out[P256_LIMBS],const BIGNUM * in)205 static int ecp_nistz256_bignum_to_field_elem(BN_ULONG out[P256_LIMBS],
206                                              const BIGNUM *in) {
207   if (in->top > P256_LIMBS) {
208     return 0;
209   }
210 
211   OPENSSL_memset(out, 0, sizeof(BN_ULONG) * P256_LIMBS);
212   OPENSSL_memcpy(out, in->d, sizeof(BN_ULONG) * in->top);
213   return 1;
214 }
215 
216 /* r = p * p_scalar */
ecp_nistz256_windowed_mul(const EC_GROUP * group,P256_POINT * r,const EC_POINT * p,const BIGNUM * p_scalar,BN_CTX * ctx)217 static int ecp_nistz256_windowed_mul(const EC_GROUP *group, P256_POINT *r,
218                                      const EC_POINT *p, const BIGNUM *p_scalar,
219                                      BN_CTX *ctx) {
220   assert(p != NULL);
221   assert(p_scalar != NULL);
222 
223   static const unsigned kWindowSize = 5;
224   static const unsigned kMask = (1 << (5 /* kWindowSize */ + 1)) - 1;
225 
226   /* A |P256_POINT| is (3 * 32) = 96 bytes, and the 64-byte alignment should
227    * add no more than 63 bytes of overhead. Thus, |table| should require
228    * ~1599 ((96 * 16) + 63) bytes of stack space. */
229   alignas(64) P256_POINT table[16];
230   uint8_t p_str[33];
231 
232 
233   int ret = 0;
234   BN_CTX *new_ctx = NULL;
235   int ctx_started = 0;
236 
237   if (BN_num_bits(p_scalar) > 256 || BN_is_negative(p_scalar)) {
238     if (ctx == NULL) {
239       new_ctx = BN_CTX_new();
240       if (new_ctx == NULL) {
241         OPENSSL_PUT_ERROR(EC, ERR_R_MALLOC_FAILURE);
242         goto err;
243       }
244       ctx = new_ctx;
245     }
246     BN_CTX_start(ctx);
247     ctx_started = 1;
248     BIGNUM *mod = BN_CTX_get(ctx);
249     if (mod == NULL) {
250       OPENSSL_PUT_ERROR(EC, ERR_R_MALLOC_FAILURE);
251       goto err;
252     }
253     if (!BN_nnmod(mod, p_scalar, &group->order, ctx)) {
254       OPENSSL_PUT_ERROR(EC, ERR_R_BN_LIB);
255       goto err;
256     }
257     p_scalar = mod;
258   }
259 
260   int j;
261   for (j = 0; j < p_scalar->top * BN_BYTES; j += BN_BYTES) {
262     BN_ULONG d = p_scalar->d[j / BN_BYTES];
263 
264     p_str[j + 0] = d & 0xff;
265     p_str[j + 1] = (d >> 8) & 0xff;
266     p_str[j + 2] = (d >> 16) & 0xff;
267     p_str[j + 3] = (d >>= 24) & 0xff;
268     if (BN_BYTES == 8) {
269       d >>= 8;
270       p_str[j + 4] = d & 0xff;
271       p_str[j + 5] = (d >> 8) & 0xff;
272       p_str[j + 6] = (d >> 16) & 0xff;
273       p_str[j + 7] = (d >> 24) & 0xff;
274     }
275   }
276 
277   for (; j < 33; j++) {
278     p_str[j] = 0;
279   }
280 
281   /* table[0] is implicitly (0,0,0) (the point at infinity), therefore it is
282    * not stored. All other values are actually stored with an offset of -1 in
283    * table. */
284   P256_POINT *row = table;
285 
286   if (!ecp_nistz256_bignum_to_field_elem(row[1 - 1].X, &p->X) ||
287       !ecp_nistz256_bignum_to_field_elem(row[1 - 1].Y, &p->Y) ||
288       !ecp_nistz256_bignum_to_field_elem(row[1 - 1].Z, &p->Z)) {
289     OPENSSL_PUT_ERROR(EC, EC_R_COORDINATES_OUT_OF_RANGE);
290     goto err;
291   }
292 
293   ecp_nistz256_point_double(&row[2 - 1], &row[1 - 1]);
294   ecp_nistz256_point_add(&row[3 - 1], &row[2 - 1], &row[1 - 1]);
295   ecp_nistz256_point_double(&row[4 - 1], &row[2 - 1]);
296   ecp_nistz256_point_double(&row[6 - 1], &row[3 - 1]);
297   ecp_nistz256_point_double(&row[8 - 1], &row[4 - 1]);
298   ecp_nistz256_point_double(&row[12 - 1], &row[6 - 1]);
299   ecp_nistz256_point_add(&row[5 - 1], &row[4 - 1], &row[1 - 1]);
300   ecp_nistz256_point_add(&row[7 - 1], &row[6 - 1], &row[1 - 1]);
301   ecp_nistz256_point_add(&row[9 - 1], &row[8 - 1], &row[1 - 1]);
302   ecp_nistz256_point_add(&row[13 - 1], &row[12 - 1], &row[1 - 1]);
303   ecp_nistz256_point_double(&row[14 - 1], &row[7 - 1]);
304   ecp_nistz256_point_double(&row[10 - 1], &row[5 - 1]);
305   ecp_nistz256_point_add(&row[15 - 1], &row[14 - 1], &row[1 - 1]);
306   ecp_nistz256_point_add(&row[11 - 1], &row[10 - 1], &row[1 - 1]);
307   ecp_nistz256_point_double(&row[16 - 1], &row[8 - 1]);
308 
309   BN_ULONG tmp[P256_LIMBS];
310   alignas(32) P256_POINT h;
311   unsigned index = 255;
312   unsigned wvalue = p_str[(index - 1) / 8];
313   wvalue = (wvalue >> ((index - 1) % 8)) & kMask;
314 
315   ecp_nistz256_select_w5(r, table, booth_recode_w5(wvalue) >> 1);
316 
317   while (index >= 5) {
318     if (index != 255) {
319       unsigned off = (index - 1) / 8;
320 
321       wvalue = p_str[off] | p_str[off + 1] << 8;
322       wvalue = (wvalue >> ((index - 1) % 8)) & kMask;
323 
324       wvalue = booth_recode_w5(wvalue);
325 
326       ecp_nistz256_select_w5(&h, table, wvalue >> 1);
327 
328       ecp_nistz256_neg(tmp, h.Y);
329       copy_conditional(h.Y, tmp, (wvalue & 1));
330 
331       ecp_nistz256_point_add(r, r, &h);
332     }
333 
334     index -= kWindowSize;
335 
336     ecp_nistz256_point_double(r, r);
337     ecp_nistz256_point_double(r, r);
338     ecp_nistz256_point_double(r, r);
339     ecp_nistz256_point_double(r, r);
340     ecp_nistz256_point_double(r, r);
341   }
342 
343   /* Final window */
344   wvalue = p_str[0];
345   wvalue = (wvalue << 1) & kMask;
346 
347   wvalue = booth_recode_w5(wvalue);
348 
349   ecp_nistz256_select_w5(&h, table, wvalue >> 1);
350 
351   ecp_nistz256_neg(tmp, h.Y);
352   copy_conditional(h.Y, tmp, wvalue & 1);
353 
354   ecp_nistz256_point_add(r, r, &h);
355 
356   ret = 1;
357 
358 err:
359   if (ctx_started) {
360     BN_CTX_end(ctx);
361   }
362   BN_CTX_free(new_ctx);
363   return ret;
364 }
365 
ecp_nistz256_points_mul(const EC_GROUP * group,EC_POINT * r,const BIGNUM * g_scalar,const EC_POINT * p_,const BIGNUM * p_scalar,BN_CTX * ctx)366 static int ecp_nistz256_points_mul(
367     const EC_GROUP *group, EC_POINT *r, const BIGNUM *g_scalar,
368     const EC_POINT *p_, const BIGNUM *p_scalar, BN_CTX *ctx) {
369   assert((p_ != NULL) == (p_scalar != NULL));
370 
371   static const unsigned kWindowSize = 7;
372   static const unsigned kMask = (1 << (7 /* kWindowSize */ + 1)) - 1;
373 
374   alignas(32) union {
375     P256_POINT p;
376     P256_POINT_AFFINE a;
377   } t, p;
378 
379   int ret = 0;
380   BN_CTX *new_ctx = NULL;
381   int ctx_started = 0;
382 
383   if (g_scalar != NULL) {
384     if (BN_num_bits(g_scalar) > 256 || BN_is_negative(g_scalar)) {
385       if (ctx == NULL) {
386         new_ctx = BN_CTX_new();
387         if (new_ctx == NULL) {
388           goto err;
389         }
390         ctx = new_ctx;
391       }
392       BN_CTX_start(ctx);
393       ctx_started = 1;
394       BIGNUM *tmp_scalar = BN_CTX_get(ctx);
395       if (tmp_scalar == NULL) {
396         goto err;
397       }
398 
399       if (!BN_nnmod(tmp_scalar, g_scalar, &group->order, ctx)) {
400         OPENSSL_PUT_ERROR(EC, ERR_R_BN_LIB);
401         goto err;
402       }
403       g_scalar = tmp_scalar;
404     }
405 
406     uint8_t p_str[33] = {0};
407     int i;
408     for (i = 0; i < g_scalar->top * BN_BYTES; i += BN_BYTES) {
409       BN_ULONG d = g_scalar->d[i / BN_BYTES];
410 
411       p_str[i + 0] = d & 0xff;
412       p_str[i + 1] = (d >> 8) & 0xff;
413       p_str[i + 2] = (d >> 16) & 0xff;
414       p_str[i + 3] = (d >>= 24) & 0xff;
415       if (BN_BYTES == 8) {
416         d >>= 8;
417         p_str[i + 4] = d & 0xff;
418         p_str[i + 5] = (d >> 8) & 0xff;
419         p_str[i + 6] = (d >> 16) & 0xff;
420         p_str[i + 7] = (d >> 24) & 0xff;
421       }
422     }
423 
424     for (; i < (int) sizeof(p_str); i++) {
425       p_str[i] = 0;
426     }
427 
428     /* First window */
429     unsigned wvalue = (p_str[0] << 1) & kMask;
430     unsigned index = kWindowSize;
431 
432     wvalue = booth_recode_w7(wvalue);
433 
434     const PRECOMP256_ROW *const precomputed_table =
435         (const PRECOMP256_ROW *)ecp_nistz256_precomputed;
436     ecp_nistz256_select_w7(&p.a, precomputed_table[0], wvalue >> 1);
437 
438     ecp_nistz256_neg(p.p.Z, p.p.Y);
439     copy_conditional(p.p.Y, p.p.Z, wvalue & 1);
440 
441     /* Convert |p| from affine to Jacobian coordinates. We set Z to zero if |p|
442      * is infinity and |ONE| otherwise. |p| was computed from the table, so it
443      * is infinity iff |wvalue >> 1| is zero.  */
444     OPENSSL_memset(p.p.Z, 0, sizeof(p.p.Z));
445     copy_conditional(p.p.Z, ONE, is_not_zero(wvalue >> 1));
446 
447     for (i = 1; i < 37; i++) {
448       unsigned off = (index - 1) / 8;
449       wvalue = p_str[off] | p_str[off + 1] << 8;
450       wvalue = (wvalue >> ((index - 1) % 8)) & kMask;
451       index += kWindowSize;
452 
453       wvalue = booth_recode_w7(wvalue);
454 
455       ecp_nistz256_select_w7(&t.a, precomputed_table[i], wvalue >> 1);
456 
457       ecp_nistz256_neg(t.p.Z, t.a.Y);
458       copy_conditional(t.a.Y, t.p.Z, wvalue & 1);
459 
460       ecp_nistz256_point_add_affine(&p.p, &p.p, &t.a);
461     }
462   }
463 
464   const int p_is_infinity = g_scalar == NULL;
465   if (p_scalar != NULL) {
466     P256_POINT *out = &t.p;
467     if (p_is_infinity) {
468       out = &p.p;
469     }
470 
471     if (!ecp_nistz256_windowed_mul(group, out, p_, p_scalar, ctx)) {
472       goto err;
473     }
474 
475     if (!p_is_infinity) {
476       ecp_nistz256_point_add(&p.p, &p.p, out);
477     }
478   }
479 
480   /* Not constant-time, but we're only operating on the public output. */
481   if (!bn_set_words(&r->X, p.p.X, P256_LIMBS) ||
482       !bn_set_words(&r->Y, p.p.Y, P256_LIMBS) ||
483       !bn_set_words(&r->Z, p.p.Z, P256_LIMBS)) {
484     return 0;
485   }
486 
487   ret = 1;
488 
489 err:
490   if (ctx_started) {
491     BN_CTX_end(ctx);
492   }
493   BN_CTX_free(new_ctx);
494   return ret;
495 }
496 
ecp_nistz256_get_affine(const EC_GROUP * group,const EC_POINT * point,BIGNUM * x,BIGNUM * y,BN_CTX * ctx)497 static int ecp_nistz256_get_affine(const EC_GROUP *group, const EC_POINT *point,
498                                    BIGNUM *x, BIGNUM *y, BN_CTX *ctx) {
499   BN_ULONG z_inv2[P256_LIMBS];
500   BN_ULONG z_inv3[P256_LIMBS];
501   BN_ULONG point_x[P256_LIMBS], point_y[P256_LIMBS], point_z[P256_LIMBS];
502 
503   if (EC_POINT_is_at_infinity(group, point)) {
504     OPENSSL_PUT_ERROR(EC, EC_R_POINT_AT_INFINITY);
505     return 0;
506   }
507 
508   if (!ecp_nistz256_bignum_to_field_elem(point_x, &point->X) ||
509       !ecp_nistz256_bignum_to_field_elem(point_y, &point->Y) ||
510       !ecp_nistz256_bignum_to_field_elem(point_z, &point->Z)) {
511     OPENSSL_PUT_ERROR(EC, EC_R_COORDINATES_OUT_OF_RANGE);
512     return 0;
513   }
514 
515   ecp_nistz256_mod_inverse_mont(z_inv3, point_z);
516   ecp_nistz256_sqr_mont(z_inv2, z_inv3);
517 
518   /* Instead of using |ecp_nistz256_from_mont| to convert the |x| coordinate
519    * and then calling |ecp_nistz256_from_mont| again to convert the |y|
520    * coordinate below, convert the common factor |z_inv2| once now, saving one
521    * reduction. */
522   ecp_nistz256_from_mont(z_inv2, z_inv2);
523 
524   if (x != NULL) {
525     BN_ULONG x_aff[P256_LIMBS];
526     ecp_nistz256_mul_mont(x_aff, z_inv2, point_x);
527     if (!bn_set_words(x, x_aff, P256_LIMBS)) {
528       OPENSSL_PUT_ERROR(EC, ERR_R_MALLOC_FAILURE);
529       return 0;
530     }
531   }
532 
533   if (y != NULL) {
534     BN_ULONG y_aff[P256_LIMBS];
535     ecp_nistz256_mul_mont(z_inv3, z_inv3, z_inv2);
536     ecp_nistz256_mul_mont(y_aff, z_inv3, point_y);
537     if (!bn_set_words(y, y_aff, P256_LIMBS)) {
538       OPENSSL_PUT_ERROR(EC, ERR_R_MALLOC_FAILURE);
539       return 0;
540     }
541   }
542 
543   return 1;
544 }
545 
546 
547 const EC_METHOD EC_GFp_nistz256_method = {
548     ec_GFp_mont_group_init,
549     ec_GFp_mont_group_finish,
550     ec_GFp_mont_group_copy,
551     ec_GFp_mont_group_set_curve,
552     ecp_nistz256_get_affine,
553     ecp_nistz256_points_mul,
554     ec_GFp_mont_field_mul,
555     ec_GFp_mont_field_sqr,
556     ec_GFp_mont_field_encode,
557     ec_GFp_mont_field_decode,
558 };
559 
560 #endif /* !defined(OPENSSL_NO_ASM) && defined(OPENSSL_X86_64) && \
561           !defined(OPENSSL_SMALL) */
562