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      1 /* crypto/bn/bn_nist.c */
      2 /*
      3  * Written by Nils Larsch for the OpenSSL project
      4  */
      5 /* ====================================================================
      6  * Copyright (c) 1998-2005 The OpenSSL Project.  All rights reserved.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  *
     12  * 1. Redistributions of source code must retain the above copyright
     13  *    notice, this list of conditions and the following disclaimer.
     14  *
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in
     17  *    the documentation and/or other materials provided with the
     18  *    distribution.
     19  *
     20  * 3. All advertising materials mentioning features or use of this
     21  *    software must display the following acknowledgment:
     22  *    "This product includes software developed by the OpenSSL Project
     23  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
     24  *
     25  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
     26  *    endorse or promote products derived from this software without
     27  *    prior written permission. For written permission, please contact
     28  *    openssl-core (at) openssl.org.
     29  *
     30  * 5. Products derived from this software may not be called "OpenSSL"
     31  *    nor may "OpenSSL" appear in their names without prior written
     32  *    permission of the OpenSSL Project.
     33  *
     34  * 6. Redistributions of any form whatsoever must retain the following
     35  *    acknowledgment:
     36  *    "This product includes software developed by the OpenSSL Project
     37  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
     38  *
     39  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
     40  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     41  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     42  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
     43  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     44  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     45  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     46  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     47  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
     48  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     49  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
     50  * OF THE POSSIBILITY OF SUCH DAMAGE.
     51  * ====================================================================
     52  *
     53  * This product includes cryptographic software written by Eric Young
     54  * (eay (at) cryptsoft.com).  This product includes software written by Tim
     55  * Hudson (tjh (at) cryptsoft.com).
     56  *
     57  */
     58 
     59 #include "bn_lcl.h"
     60 #include "cryptlib.h"
     61 
     62 
     63 #define BN_NIST_192_TOP	(192+BN_BITS2-1)/BN_BITS2
     64 #define BN_NIST_224_TOP	(224+BN_BITS2-1)/BN_BITS2
     65 #define BN_NIST_256_TOP	(256+BN_BITS2-1)/BN_BITS2
     66 #define BN_NIST_384_TOP	(384+BN_BITS2-1)/BN_BITS2
     67 #define BN_NIST_521_TOP	(521+BN_BITS2-1)/BN_BITS2
     68 
     69 /* pre-computed tables are "carry-less" values of modulus*(i+1) */
     70 #if BN_BITS2 == 64
     71 static const BN_ULONG _nist_p_192[][BN_NIST_192_TOP] = {
     72 	{0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFEULL,0xFFFFFFFFFFFFFFFFULL},
     73 	{0xFFFFFFFFFFFFFFFEULL,0xFFFFFFFFFFFFFFFDULL,0xFFFFFFFFFFFFFFFFULL},
     74 	{0xFFFFFFFFFFFFFFFDULL,0xFFFFFFFFFFFFFFFCULL,0xFFFFFFFFFFFFFFFFULL}
     75 	};
     76 static const BN_ULONG _nist_p_192_sqr[] = {
     77 	0x0000000000000001ULL,0x0000000000000002ULL,0x0000000000000001ULL,
     78 	0xFFFFFFFFFFFFFFFEULL,0xFFFFFFFFFFFFFFFDULL,0xFFFFFFFFFFFFFFFFULL
     79 	};
     80 static const BN_ULONG _nist_p_224[][BN_NIST_224_TOP] = {
     81 	{0x0000000000000001ULL,0xFFFFFFFF00000000ULL,
     82 	 0xFFFFFFFFFFFFFFFFULL,0x00000000FFFFFFFFULL},
     83 	{0x0000000000000002ULL,0xFFFFFFFE00000000ULL,
     84 	 0xFFFFFFFFFFFFFFFFULL,0x00000001FFFFFFFFULL} /* this one is "carry-full" */
     85 	};
     86 static const BN_ULONG _nist_p_224_sqr[] = {
     87 	0x0000000000000001ULL,0xFFFFFFFE00000000ULL,
     88 	0xFFFFFFFFFFFFFFFFULL,0x0000000200000000ULL,
     89 	0x0000000000000000ULL,0xFFFFFFFFFFFFFFFEULL,
     90 	0xFFFFFFFFFFFFFFFFULL
     91 	};
     92 static const BN_ULONG _nist_p_256[][BN_NIST_256_TOP] = {
     93 	{0xFFFFFFFFFFFFFFFFULL,0x00000000FFFFFFFFULL,
     94 	 0x0000000000000000ULL,0xFFFFFFFF00000001ULL},
     95 	{0xFFFFFFFFFFFFFFFEULL,0x00000001FFFFFFFFULL,
     96 	 0x0000000000000000ULL,0xFFFFFFFE00000002ULL},
     97 	{0xFFFFFFFFFFFFFFFDULL,0x00000002FFFFFFFFULL,
     98 	 0x0000000000000000ULL,0xFFFFFFFD00000003ULL},
     99 	{0xFFFFFFFFFFFFFFFCULL,0x00000003FFFFFFFFULL,
    100 	 0x0000000000000000ULL,0xFFFFFFFC00000004ULL},
    101 	{0xFFFFFFFFFFFFFFFBULL,0x00000004FFFFFFFFULL,
    102 	 0x0000000000000000ULL,0xFFFFFFFB00000005ULL},
    103 	};
    104 static const BN_ULONG _nist_p_256_sqr[] = {
    105 	0x0000000000000001ULL,0xFFFFFFFE00000000ULL,
    106 	0xFFFFFFFFFFFFFFFFULL,0x00000001FFFFFFFEULL,
    107 	0x00000001FFFFFFFEULL,0x00000001FFFFFFFEULL,
    108 	0xFFFFFFFE00000001ULL,0xFFFFFFFE00000002ULL
    109 	};
    110 static const BN_ULONG _nist_p_384[][BN_NIST_384_TOP] = {
    111 	{0x00000000FFFFFFFFULL,0xFFFFFFFF00000000ULL,0xFFFFFFFFFFFFFFFEULL,
    112 	 0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL},
    113 	{0x00000001FFFFFFFEULL,0xFFFFFFFE00000000ULL,0xFFFFFFFFFFFFFFFDULL,
    114 	 0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL},
    115 	{0x00000002FFFFFFFDULL,0xFFFFFFFD00000000ULL,0xFFFFFFFFFFFFFFFCULL,
    116 	 0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL},
    117 	{0x00000003FFFFFFFCULL,0xFFFFFFFC00000000ULL,0xFFFFFFFFFFFFFFFBULL,
    118 	 0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL},
    119 	{0x00000004FFFFFFFBULL,0xFFFFFFFB00000000ULL,0xFFFFFFFFFFFFFFFAULL,
    120 	 0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL},
    121 	};
    122 static const BN_ULONG _nist_p_384_sqr[] = {
    123 	0xFFFFFFFE00000001ULL,0x0000000200000000ULL,0xFFFFFFFE00000000ULL,
    124 	0x0000000200000000ULL,0x0000000000000001ULL,0x0000000000000000ULL,
    125 	0x00000001FFFFFFFEULL,0xFFFFFFFE00000000ULL,0xFFFFFFFFFFFFFFFDULL,
    126 	0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL
    127 	};
    128 static const BN_ULONG _nist_p_521[] =
    129 	{0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,
    130 	0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,
    131 	0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,
    132 	0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,
    133 	0x00000000000001FFULL};
    134 static const BN_ULONG _nist_p_521_sqr[] = {
    135 	0x0000000000000001ULL,0x0000000000000000ULL,0x0000000000000000ULL,
    136 	0x0000000000000000ULL,0x0000000000000000ULL,0x0000000000000000ULL,
    137 	0x0000000000000000ULL,0x0000000000000000ULL,0xFFFFFFFFFFFFFC00ULL,
    138 	0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,
    139 	0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,
    140 	0xFFFFFFFFFFFFFFFFULL,0x000000000003FFFFULL
    141 	};
    142 #elif BN_BITS2 == 32
    143 static const BN_ULONG _nist_p_192[][BN_NIST_192_TOP] = {
    144 	{0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFE,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF},
    145 	{0xFFFFFFFE,0xFFFFFFFF,0xFFFFFFFD,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF},
    146 	{0xFFFFFFFD,0xFFFFFFFF,0xFFFFFFFC,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF}
    147 	};
    148 static const BN_ULONG _nist_p_192_sqr[] = {
    149 	0x00000001,0x00000000,0x00000002,0x00000000,0x00000001,0x00000000,
    150 	0xFFFFFFFE,0xFFFFFFFF,0xFFFFFFFD,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF
    151 	};
    152 static const BN_ULONG _nist_p_224[][BN_NIST_224_TOP] = {
    153 	{0x00000001,0x00000000,0x00000000,0xFFFFFFFF,
    154 	 0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF},
    155 	{0x00000002,0x00000000,0x00000000,0xFFFFFFFE,
    156 	 0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF}
    157 	};
    158 static const BN_ULONG _nist_p_224_sqr[] = {
    159 	0x00000001,0x00000000,0x00000000,0xFFFFFFFE,
    160 	0xFFFFFFFF,0xFFFFFFFF,0x00000000,0x00000002,
    161 	0x00000000,0x00000000,0xFFFFFFFE,0xFFFFFFFF,
    162 	0xFFFFFFFF,0xFFFFFFFF
    163 	};
    164 static const BN_ULONG _nist_p_256[][BN_NIST_256_TOP] = {
    165 	{0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0x00000000,
    166 	 0x00000000,0x00000000,0x00000001,0xFFFFFFFF},
    167 	{0xFFFFFFFE,0xFFFFFFFF,0xFFFFFFFF,0x00000001,
    168 	 0x00000000,0x00000000,0x00000002,0xFFFFFFFE},
    169 	{0xFFFFFFFD,0xFFFFFFFF,0xFFFFFFFF,0x00000002,
    170 	 0x00000000,0x00000000,0x00000003,0xFFFFFFFD},
    171 	{0xFFFFFFFC,0xFFFFFFFF,0xFFFFFFFF,0x00000003,
    172 	 0x00000000,0x00000000,0x00000004,0xFFFFFFFC},
    173 	{0xFFFFFFFB,0xFFFFFFFF,0xFFFFFFFF,0x00000004,
    174 	 0x00000000,0x00000000,0x00000005,0xFFFFFFFB},
    175 	};
    176 static const BN_ULONG _nist_p_256_sqr[] = {
    177 	0x00000001,0x00000000,0x00000000,0xFFFFFFFE,
    178 	0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFE,0x00000001,
    179 	0xFFFFFFFE,0x00000001,0xFFFFFFFE,0x00000001,
    180 	0x00000001,0xFFFFFFFE,0x00000002,0xFFFFFFFE
    181 	};
    182 static const BN_ULONG _nist_p_384[][BN_NIST_384_TOP] = {
    183 	{0xFFFFFFFF,0x00000000,0x00000000,0xFFFFFFFF,0xFFFFFFFE,0xFFFFFFFF,
    184 	 0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF},
    185 	{0xFFFFFFFE,0x00000001,0x00000000,0xFFFFFFFE,0xFFFFFFFD,0xFFFFFFFF,
    186 	 0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF},
    187 	{0xFFFFFFFD,0x00000002,0x00000000,0xFFFFFFFD,0xFFFFFFFC,0xFFFFFFFF,
    188 	 0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF},
    189 	{0xFFFFFFFC,0x00000003,0x00000000,0xFFFFFFFC,0xFFFFFFFB,0xFFFFFFFF,
    190 	 0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF},
    191 	{0xFFFFFFFB,0x00000004,0x00000000,0xFFFFFFFB,0xFFFFFFFA,0xFFFFFFFF,
    192 	 0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF},
    193 	};
    194 static const BN_ULONG _nist_p_384_sqr[] = {
    195 	0x00000001,0xFFFFFFFE,0x00000000,0x00000002,0x00000000,0xFFFFFFFE,
    196 	0x00000000,0x00000002,0x00000001,0x00000000,0x00000000,0x00000000,
    197 	0xFFFFFFFE,0x00000001,0x00000000,0xFFFFFFFE,0xFFFFFFFD,0xFFFFFFFF,
    198 	0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF
    199 	};
    200 static const BN_ULONG _nist_p_521[] = {0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,
    201 	0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,
    202 	0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,
    203 	0xFFFFFFFF,0x000001FF};
    204 static const BN_ULONG _nist_p_521_sqr[] = {
    205 	0x00000001,0x00000000,0x00000000,0x00000000,0x00000000,0x00000000,
    206 	0x00000000,0x00000000,0x00000000,0x00000000,0x00000000,0x00000000,
    207 	0x00000000,0x00000000,0x00000000,0x00000000,0xFFFFFC00,0xFFFFFFFF,
    208 	0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,
    209 	0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,
    210 	0xFFFFFFFF,0xFFFFFFFF,0x0003FFFF
    211 	};
    212 #else
    213 #error "unsupported BN_BITS2"
    214 #endif
    215 
    216 
    217 static const BIGNUM _bignum_nist_p_192 =
    218 	{
    219 	(BN_ULONG *)_nist_p_192[0],
    220 	BN_NIST_192_TOP,
    221 	BN_NIST_192_TOP,
    222 	0,
    223 	BN_FLG_STATIC_DATA
    224 	};
    225 
    226 static const BIGNUM _bignum_nist_p_224 =
    227 	{
    228 	(BN_ULONG *)_nist_p_224[0],
    229 	BN_NIST_224_TOP,
    230 	BN_NIST_224_TOP,
    231 	0,
    232 	BN_FLG_STATIC_DATA
    233 	};
    234 
    235 static const BIGNUM _bignum_nist_p_256 =
    236 	{
    237 	(BN_ULONG *)_nist_p_256[0],
    238 	BN_NIST_256_TOP,
    239 	BN_NIST_256_TOP,
    240 	0,
    241 	BN_FLG_STATIC_DATA
    242 	};
    243 
    244 static const BIGNUM _bignum_nist_p_384 =
    245 	{
    246 	(BN_ULONG *)_nist_p_384[0],
    247 	BN_NIST_384_TOP,
    248 	BN_NIST_384_TOP,
    249 	0,
    250 	BN_FLG_STATIC_DATA
    251 	};
    252 
    253 static const BIGNUM _bignum_nist_p_521 =
    254 	{
    255 	(BN_ULONG *)_nist_p_521,
    256 	BN_NIST_521_TOP,
    257 	BN_NIST_521_TOP,
    258 	0,
    259 	BN_FLG_STATIC_DATA
    260 	};
    261 
    262 
    263 const BIGNUM *BN_get0_nist_prime_192(void)
    264 	{
    265 	return &_bignum_nist_p_192;
    266 	}
    267 
    268 const BIGNUM *BN_get0_nist_prime_224(void)
    269 	{
    270 	return &_bignum_nist_p_224;
    271 	}
    272 
    273 const BIGNUM *BN_get0_nist_prime_256(void)
    274 	{
    275 	return &_bignum_nist_p_256;
    276 	}
    277 
    278 const BIGNUM *BN_get0_nist_prime_384(void)
    279 	{
    280 	return &_bignum_nist_p_384;
    281 	}
    282 
    283 const BIGNUM *BN_get0_nist_prime_521(void)
    284 	{
    285 	return &_bignum_nist_p_521;
    286 	}
    287 
    288 
    289 static void nist_cp_bn_0(BN_ULONG *buf, BN_ULONG *a, int top, int max)
    290 	{
    291 	int i;
    292 	BN_ULONG *_tmp1 = (buf), *_tmp2 = (a);
    293 
    294 #ifdef BN_DEBUG
    295 	OPENSSL_assert(top <= max);
    296 #endif
    297 	for (i = (top); i != 0; i--)
    298 		*_tmp1++ = *_tmp2++;
    299 	for (i = (max) - (top); i != 0; i--)
    300 		*_tmp1++ = (BN_ULONG) 0;
    301 	}
    302 
    303 static void nist_cp_bn(BN_ULONG *buf, BN_ULONG *a, int top)
    304 	{
    305 	int i;
    306 	BN_ULONG *_tmp1 = (buf), *_tmp2 = (a);
    307 	for (i = (top); i != 0; i--)
    308 		*_tmp1++ = *_tmp2++;
    309 	}
    310 
    311 #if BN_BITS2 == 64
    312 #define bn_cp_64(to, n, from, m)	(to)[n] = (m>=0)?((from)[m]):0;
    313 #define bn_64_set_0(to, n)		(to)[n] = (BN_ULONG)0;
    314 /*
    315  * two following macros are implemented under assumption that they
    316  * are called in a sequence with *ascending* n, i.e. as they are...
    317  */
    318 #define bn_cp_32_naked(to, n, from, m)	(((n)&1)?(to[(n)/2]|=((m)&1)?(from[(m)/2]&BN_MASK2h):(from[(m)/2]<<32))\
    319 						:(to[(n)/2] =((m)&1)?(from[(m)/2]>>32):(from[(m)/2]&BN_MASK2l)))
    320 #define bn_32_set_0(to, n)		(((n)&1)?(to[(n)/2]&=BN_MASK2l):(to[(n)/2]=0));
    321 #define bn_cp_32(to,n,from,m)		((m)>=0)?bn_cp_32_naked(to,n,from,m):bn_32_set_0(to,n)
    322 #else
    323 #define bn_cp_64(to, n, from, m) \
    324 	{ \
    325 	bn_cp_32(to, (n)*2, from, (m)*2); \
    326 	bn_cp_32(to, (n)*2+1, from, (m)*2+1); \
    327 	}
    328 #define bn_64_set_0(to, n) \
    329 	{ \
    330 	bn_32_set_0(to, (n)*2); \
    331 	bn_32_set_0(to, (n)*2+1); \
    332 	}
    333 #if BN_BITS2 == 32
    334 #define bn_cp_32(to, n, from, m)	(to)[n] = (m>=0)?((from)[m]):0;
    335 #define bn_32_set_0(to, n)		(to)[n] = (BN_ULONG)0;
    336 #endif
    337 #endif /* BN_BITS2 != 64 */
    338 
    339 
    340 #define nist_set_192(to, from, a1, a2, a3) \
    341 	{ \
    342 	bn_cp_64(to, 0, from, (a3) - 3) \
    343 	bn_cp_64(to, 1, from, (a2) - 3) \
    344 	bn_cp_64(to, 2, from, (a1) - 3) \
    345 	}
    346 
    347 int BN_nist_mod_192(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
    348 	BN_CTX *ctx)
    349 	{
    350 	int      top = a->top, i;
    351 	int      carry;
    352 	register BN_ULONG *r_d, *a_d = a->d;
    353 	BN_ULONG t_d[BN_NIST_192_TOP],
    354 	         buf[BN_NIST_192_TOP],
    355 		 c_d[BN_NIST_192_TOP],
    356 		*res;
    357 	PTR_SIZE_INT mask;
    358 	static const BIGNUM _bignum_nist_p_192_sqr = {
    359 		(BN_ULONG *)_nist_p_192_sqr,
    360 		sizeof(_nist_p_192_sqr)/sizeof(_nist_p_192_sqr[0]),
    361 		sizeof(_nist_p_192_sqr)/sizeof(_nist_p_192_sqr[0]),
    362 		0,BN_FLG_STATIC_DATA };
    363 
    364 	field = &_bignum_nist_p_192; /* just to make sure */
    365 
    366  	if (BN_is_negative(a) || BN_ucmp(a,&_bignum_nist_p_192_sqr)>=0)
    367 		return BN_nnmod(r, a, field, ctx);
    368 
    369 	i = BN_ucmp(field, a);
    370 	if (i == 0)
    371 		{
    372 		BN_zero(r);
    373 		return 1;
    374 		}
    375 	else if (i > 0)
    376 		return (r == a) ? 1 : (BN_copy(r ,a) != NULL);
    377 
    378 	if (r != a)
    379 		{
    380 		if (!bn_wexpand(r, BN_NIST_192_TOP))
    381 			return 0;
    382 		r_d = r->d;
    383 		nist_cp_bn(r_d, a_d, BN_NIST_192_TOP);
    384 		}
    385 	else
    386 		r_d = a_d;
    387 
    388 	nist_cp_bn_0(buf, a_d + BN_NIST_192_TOP, top - BN_NIST_192_TOP, BN_NIST_192_TOP);
    389 
    390 	nist_set_192(t_d, buf, 0, 3, 3);
    391 	carry = (int)bn_add_words(r_d, r_d, t_d, BN_NIST_192_TOP);
    392 	nist_set_192(t_d, buf, 4, 4, 0);
    393 	carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_192_TOP);
    394 	nist_set_192(t_d, buf, 5, 5, 5)
    395 	carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_192_TOP);
    396 
    397 	if (carry > 0)
    398 		carry = (int)bn_sub_words(r_d,r_d,_nist_p_192[carry-1],BN_NIST_192_TOP);
    399 	else
    400 		carry = 1;
    401 
    402 	/*
    403 	 * we need 'if (carry==0 || result>=modulus) result-=modulus;'
    404 	 * as comparison implies subtraction, we can write
    405 	 * 'tmp=result-modulus; if (!carry || !borrow) result=tmp;'
    406 	 * this is what happens below, but without explicit if:-) a.
    407 	 */
    408 	mask  = 0-(PTR_SIZE_INT)bn_sub_words(c_d,r_d,_nist_p_192[0],BN_NIST_192_TOP);
    409 	mask &= 0-(PTR_SIZE_INT)carry;
    410 	res   = (BN_ULONG *)
    411 	 (((PTR_SIZE_INT)c_d&~mask) | ((PTR_SIZE_INT)r_d&mask));
    412 	nist_cp_bn(r_d, res, BN_NIST_192_TOP);
    413 	r->top = BN_NIST_192_TOP;
    414 	bn_correct_top(r);
    415 
    416 	return 1;
    417 	}
    418 
    419 typedef BN_ULONG (*bn_addsub_f)(BN_ULONG *,const BN_ULONG *,const BN_ULONG *,int);
    420 
    421 #define nist_set_224(to, from, a1, a2, a3, a4, a5, a6, a7) \
    422 	{ \
    423 	bn_cp_32(to, 0, from, (a7) - 7) \
    424 	bn_cp_32(to, 1, from, (a6) - 7) \
    425 	bn_cp_32(to, 2, from, (a5) - 7) \
    426 	bn_cp_32(to, 3, from, (a4) - 7) \
    427 	bn_cp_32(to, 4, from, (a3) - 7) \
    428 	bn_cp_32(to, 5, from, (a2) - 7) \
    429 	bn_cp_32(to, 6, from, (a1) - 7) \
    430 	}
    431 
    432 int BN_nist_mod_224(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
    433 	BN_CTX *ctx)
    434 	{
    435 	int	top = a->top, i;
    436 	int	carry;
    437 	BN_ULONG *r_d, *a_d = a->d;
    438 	BN_ULONG t_d[BN_NIST_224_TOP],
    439 	         buf[BN_NIST_224_TOP],
    440 		 c_d[BN_NIST_224_TOP],
    441 		*res;
    442 	PTR_SIZE_INT mask;
    443 	union { bn_addsub_f f; PTR_SIZE_INT p; } u;
    444 	static const BIGNUM _bignum_nist_p_224_sqr = {
    445 		(BN_ULONG *)_nist_p_224_sqr,
    446 		sizeof(_nist_p_224_sqr)/sizeof(_nist_p_224_sqr[0]),
    447 		sizeof(_nist_p_224_sqr)/sizeof(_nist_p_224_sqr[0]),
    448 		0,BN_FLG_STATIC_DATA };
    449 
    450 
    451 	field = &_bignum_nist_p_224; /* just to make sure */
    452 
    453  	if (BN_is_negative(a) || BN_ucmp(a,&_bignum_nist_p_224_sqr)>=0)
    454 		return BN_nnmod(r, a, field, ctx);
    455 
    456 	i = BN_ucmp(field, a);
    457 	if (i == 0)
    458 		{
    459 		BN_zero(r);
    460 		return 1;
    461 		}
    462 	else if (i > 0)
    463 		return (r == a)? 1 : (BN_copy(r ,a) != NULL);
    464 
    465 	if (r != a)
    466 		{
    467 		if (!bn_wexpand(r, BN_NIST_224_TOP))
    468 			return 0;
    469 		r_d = r->d;
    470 		nist_cp_bn(r_d, a_d, BN_NIST_224_TOP);
    471 		}
    472 	else
    473 		r_d = a_d;
    474 
    475 #if BN_BITS2==64
    476 	/* copy upper 256 bits of 448 bit number ... */
    477 	nist_cp_bn_0(t_d, a_d + (BN_NIST_224_TOP-1), top - (BN_NIST_224_TOP-1), BN_NIST_224_TOP);
    478 	/* ... and right shift by 32 to obtain upper 224 bits */
    479 	nist_set_224(buf, t_d, 14, 13, 12, 11, 10, 9, 8);
    480 	/* truncate lower part to 224 bits too */
    481 	r_d[BN_NIST_224_TOP-1] &= BN_MASK2l;
    482 #else
    483 	nist_cp_bn_0(buf, a_d + BN_NIST_224_TOP, top - BN_NIST_224_TOP, BN_NIST_224_TOP);
    484 #endif
    485 	nist_set_224(t_d, buf, 10, 9, 8, 7, 0, 0, 0);
    486 	carry = (int)bn_add_words(r_d, r_d, t_d, BN_NIST_224_TOP);
    487 	nist_set_224(t_d, buf, 0, 13, 12, 11, 0, 0, 0);
    488 	carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_224_TOP);
    489 	nist_set_224(t_d, buf, 13, 12, 11, 10, 9, 8, 7);
    490 	carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_224_TOP);
    491 	nist_set_224(t_d, buf, 0, 0, 0, 0, 13, 12, 11);
    492 	carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_224_TOP);
    493 
    494 #if BN_BITS2==64
    495 	carry = (int)(r_d[BN_NIST_224_TOP-1]>>32);
    496 #endif
    497 	u.f = bn_sub_words;
    498 	if (carry > 0)
    499 		{
    500 		carry = (int)bn_sub_words(r_d,r_d,_nist_p_224[carry-1],BN_NIST_224_TOP);
    501 #if BN_BITS2==64
    502 		carry=(int)(~(r_d[BN_NIST_224_TOP-1]>>32))&1;
    503 #endif
    504 		}
    505 	else if (carry < 0)
    506 		{
    507 		/* it's a bit more comlicated logic in this case.
    508 		 * if bn_add_words yields no carry, then result
    509 		 * has to be adjusted by unconditionally *adding*
    510 		 * the modulus. but if it does, then result has
    511 		 * to be compared to the modulus and conditionally
    512 		 * adjusted by *subtracting* the latter. */
    513 		carry = (int)bn_add_words(r_d,r_d,_nist_p_224[-carry-1],BN_NIST_224_TOP);
    514 		mask = 0-(PTR_SIZE_INT)carry;
    515 		u.p = ((PTR_SIZE_INT)bn_sub_words&mask) |
    516 		 ((PTR_SIZE_INT)bn_add_words&~mask);
    517 		}
    518 	else
    519 		carry = 1;
    520 
    521 	/* otherwise it's effectively same as in BN_nist_mod_192... */
    522 	mask  = 0-(PTR_SIZE_INT)(*u.f)(c_d,r_d,_nist_p_224[0],BN_NIST_224_TOP);
    523 	mask &= 0-(PTR_SIZE_INT)carry;
    524 	res   = (BN_ULONG *)(((PTR_SIZE_INT)c_d&~mask) |
    525 	 ((PTR_SIZE_INT)r_d&mask));
    526 	nist_cp_bn(r_d, res, BN_NIST_224_TOP);
    527 	r->top = BN_NIST_224_TOP;
    528 	bn_correct_top(r);
    529 
    530 	return 1;
    531 	}
    532 
    533 #define nist_set_256(to, from, a1, a2, a3, a4, a5, a6, a7, a8) \
    534 	{ \
    535 	bn_cp_32(to, 0, from, (a8) - 8) \
    536 	bn_cp_32(to, 1, from, (a7) - 8) \
    537 	bn_cp_32(to, 2, from, (a6) - 8) \
    538 	bn_cp_32(to, 3, from, (a5) - 8) \
    539 	bn_cp_32(to, 4, from, (a4) - 8) \
    540 	bn_cp_32(to, 5, from, (a3) - 8) \
    541 	bn_cp_32(to, 6, from, (a2) - 8) \
    542 	bn_cp_32(to, 7, from, (a1) - 8) \
    543 	}
    544 
    545 int BN_nist_mod_256(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
    546 	BN_CTX *ctx)
    547 	{
    548 	int	i, top = a->top;
    549 	int	carry = 0;
    550 	register BN_ULONG *a_d = a->d, *r_d;
    551 	BN_ULONG t_d[BN_NIST_256_TOP],
    552 	         buf[BN_NIST_256_TOP],
    553 		 c_d[BN_NIST_256_TOP],
    554 		*res;
    555 	PTR_SIZE_INT mask;
    556 	union { bn_addsub_f f; PTR_SIZE_INT p; } u;
    557 	static const BIGNUM _bignum_nist_p_256_sqr = {
    558 		(BN_ULONG *)_nist_p_256_sqr,
    559 		sizeof(_nist_p_256_sqr)/sizeof(_nist_p_256_sqr[0]),
    560 		sizeof(_nist_p_256_sqr)/sizeof(_nist_p_256_sqr[0]),
    561 		0,BN_FLG_STATIC_DATA };
    562 
    563 	field = &_bignum_nist_p_256; /* just to make sure */
    564 
    565  	if (BN_is_negative(a) || BN_ucmp(a,&_bignum_nist_p_256_sqr)>=0)
    566 		return BN_nnmod(r, a, field, ctx);
    567 
    568 	i = BN_ucmp(field, a);
    569 	if (i == 0)
    570 		{
    571 		BN_zero(r);
    572 		return 1;
    573 		}
    574 	else if (i > 0)
    575 		return (r == a)? 1 : (BN_copy(r ,a) != NULL);
    576 
    577 	if (r != a)
    578 		{
    579 		if (!bn_wexpand(r, BN_NIST_256_TOP))
    580 			return 0;
    581 		r_d = r->d;
    582 		nist_cp_bn(r_d, a_d, BN_NIST_256_TOP);
    583 		}
    584 	else
    585 		r_d = a_d;
    586 
    587 	nist_cp_bn_0(buf, a_d + BN_NIST_256_TOP, top - BN_NIST_256_TOP, BN_NIST_256_TOP);
    588 
    589 	/*S1*/
    590 	nist_set_256(t_d, buf, 15, 14, 13, 12, 11, 0, 0, 0);
    591 	/*S2*/
    592 	nist_set_256(c_d, buf, 0, 15, 14, 13, 12, 0, 0, 0);
    593 	carry = (int)bn_add_words(t_d, t_d, c_d, BN_NIST_256_TOP);
    594 	/* left shift */
    595 		{
    596 		register BN_ULONG *ap,t,c;
    597 		ap = t_d;
    598 		c=0;
    599 		for (i = BN_NIST_256_TOP; i != 0; --i)
    600 			{
    601 			t= *ap;
    602 			*(ap++)=((t<<1)|c)&BN_MASK2;
    603 			c=(t & BN_TBIT)?1:0;
    604 			}
    605 		carry <<= 1;
    606 		carry  |= c;
    607 		}
    608 	carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_256_TOP);
    609 	/*S3*/
    610 	nist_set_256(t_d, buf, 15, 14, 0, 0, 0, 10, 9, 8);
    611 	carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_256_TOP);
    612 	/*S4*/
    613 	nist_set_256(t_d, buf, 8, 13, 15, 14, 13, 11, 10, 9);
    614 	carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_256_TOP);
    615 	/*D1*/
    616 	nist_set_256(t_d, buf, 10, 8, 0, 0, 0, 13, 12, 11);
    617 	carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP);
    618 	/*D2*/
    619 	nist_set_256(t_d, buf, 11, 9, 0, 0, 15, 14, 13, 12);
    620 	carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP);
    621 	/*D3*/
    622 	nist_set_256(t_d, buf, 12, 0, 10, 9, 8, 15, 14, 13);
    623 	carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP);
    624 	/*D4*/
    625 	nist_set_256(t_d, buf, 13, 0, 11, 10, 9, 0, 15, 14);
    626 	carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP);
    627 
    628 	/* see BN_nist_mod_224 for explanation */
    629 	u.f = bn_sub_words;
    630 	if (carry > 0)
    631 		carry = (int)bn_sub_words(r_d,r_d,_nist_p_256[carry-1],BN_NIST_256_TOP);
    632 	else if (carry < 0)
    633 		{
    634 		carry = (int)bn_add_words(r_d,r_d,_nist_p_256[-carry-1],BN_NIST_256_TOP);
    635 		mask = 0-(PTR_SIZE_INT)carry;
    636 		u.p = ((PTR_SIZE_INT)bn_sub_words&mask) |
    637 		 ((PTR_SIZE_INT)bn_add_words&~mask);
    638 		}
    639 	else
    640 		carry = 1;
    641 
    642 	mask  = 0-(PTR_SIZE_INT)(*u.f)(c_d,r_d,_nist_p_256[0],BN_NIST_256_TOP);
    643 	mask &= 0-(PTR_SIZE_INT)carry;
    644 	res   = (BN_ULONG *)(((PTR_SIZE_INT)c_d&~mask) |
    645 	 ((PTR_SIZE_INT)r_d&mask));
    646 	nist_cp_bn(r_d, res, BN_NIST_256_TOP);
    647 	r->top = BN_NIST_256_TOP;
    648 	bn_correct_top(r);
    649 
    650 	return 1;
    651 	}
    652 
    653 #define nist_set_384(to,from,a1,a2,a3,a4,a5,a6,a7,a8,a9,a10,a11,a12) \
    654 	{ \
    655 	bn_cp_32(to, 0, from,  (a12) - 12) \
    656 	bn_cp_32(to, 1, from,  (a11) - 12) \
    657 	bn_cp_32(to, 2, from,  (a10) - 12) \
    658 	bn_cp_32(to, 3, from,  (a9) - 12)  \
    659 	bn_cp_32(to, 4, from,  (a8) - 12)  \
    660 	bn_cp_32(to, 5, from,  (a7) - 12)  \
    661 	bn_cp_32(to, 6, from,  (a6) - 12)  \
    662 	bn_cp_32(to, 7, from,  (a5) - 12)  \
    663 	bn_cp_32(to, 8, from,  (a4) - 12)  \
    664 	bn_cp_32(to, 9, from,  (a3) - 12)  \
    665 	bn_cp_32(to, 10, from, (a2) - 12)  \
    666 	bn_cp_32(to, 11, from, (a1) - 12)  \
    667 	}
    668 
    669 int BN_nist_mod_384(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
    670 	BN_CTX *ctx)
    671 	{
    672 	int	i, top = a->top;
    673 	int	carry = 0;
    674 	register BN_ULONG *r_d, *a_d = a->d;
    675 	BN_ULONG t_d[BN_NIST_384_TOP],
    676 	         buf[BN_NIST_384_TOP],
    677 		 c_d[BN_NIST_384_TOP],
    678 		*res;
    679 	PTR_SIZE_INT mask;
    680 	union { bn_addsub_f f; PTR_SIZE_INT p; } u;
    681 	static const BIGNUM _bignum_nist_p_384_sqr = {
    682 		(BN_ULONG *)_nist_p_384_sqr,
    683 		sizeof(_nist_p_384_sqr)/sizeof(_nist_p_384_sqr[0]),
    684 		sizeof(_nist_p_384_sqr)/sizeof(_nist_p_384_sqr[0]),
    685 		0,BN_FLG_STATIC_DATA };
    686 
    687 
    688 	field = &_bignum_nist_p_384; /* just to make sure */
    689 
    690  	if (BN_is_negative(a) || BN_ucmp(a,&_bignum_nist_p_384_sqr)>=0)
    691 		return BN_nnmod(r, a, field, ctx);
    692 
    693 	i = BN_ucmp(field, a);
    694 	if (i == 0)
    695 		{
    696 		BN_zero(r);
    697 		return 1;
    698 		}
    699 	else if (i > 0)
    700 		return (r == a)? 1 : (BN_copy(r ,a) != NULL);
    701 
    702 	if (r != a)
    703 		{
    704 		if (!bn_wexpand(r, BN_NIST_384_TOP))
    705 			return 0;
    706 		r_d = r->d;
    707 		nist_cp_bn(r_d, a_d, BN_NIST_384_TOP);
    708 		}
    709 	else
    710 		r_d = a_d;
    711 
    712 	nist_cp_bn_0(buf, a_d + BN_NIST_384_TOP, top - BN_NIST_384_TOP, BN_NIST_384_TOP);
    713 
    714 	/*S1*/
    715 	nist_set_256(t_d, buf, 0, 0, 0, 0, 0, 23-4, 22-4, 21-4);
    716 		/* left shift */
    717 		{
    718 		register BN_ULONG *ap,t,c;
    719 		ap = t_d;
    720 		c=0;
    721 		for (i = 3; i != 0; --i)
    722 			{
    723 			t= *ap;
    724 			*(ap++)=((t<<1)|c)&BN_MASK2;
    725 			c=(t & BN_TBIT)?1:0;
    726 			}
    727 		*ap=c;
    728 		}
    729 	carry = (int)bn_add_words(r_d+(128/BN_BITS2), r_d+(128/BN_BITS2),
    730 		t_d, BN_NIST_256_TOP);
    731 	/*S2 */
    732 	carry += (int)bn_add_words(r_d, r_d, buf, BN_NIST_384_TOP);
    733 	/*S3*/
    734 	nist_set_384(t_d,buf,20,19,18,17,16,15,14,13,12,23,22,21);
    735 	carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_384_TOP);
    736 	/*S4*/
    737 	nist_set_384(t_d,buf,19,18,17,16,15,14,13,12,20,0,23,0);
    738 	carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_384_TOP);
    739 	/*S5*/
    740 	nist_set_384(t_d, buf,0,0,0,0,23,22,21,20,0,0,0,0);
    741 	carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_384_TOP);
    742 	/*S6*/
    743 	nist_set_384(t_d,buf,0,0,0,0,0,0,23,22,21,0,0,20);
    744 	carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_384_TOP);
    745 	/*D1*/
    746 	nist_set_384(t_d,buf,22,21,20,19,18,17,16,15,14,13,12,23);
    747 	carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_384_TOP);
    748 	/*D2*/
    749 	nist_set_384(t_d,buf,0,0,0,0,0,0,0,23,22,21,20,0);
    750 	carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_384_TOP);
    751 	/*D3*/
    752 	nist_set_384(t_d,buf,0,0,0,0,0,0,0,23,23,0,0,0);
    753 	carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_384_TOP);
    754 
    755 	/* see BN_nist_mod_224 for explanation */
    756 	u.f = bn_sub_words;
    757 	if (carry > 0)
    758 		carry = (int)bn_sub_words(r_d,r_d,_nist_p_384[carry-1],BN_NIST_384_TOP);
    759 	else if (carry < 0)
    760 		{
    761 		carry = (int)bn_add_words(r_d,r_d,_nist_p_384[-carry-1],BN_NIST_384_TOP);
    762 		mask = 0-(PTR_SIZE_INT)carry;
    763 		u.p = ((PTR_SIZE_INT)bn_sub_words&mask) |
    764 		 ((PTR_SIZE_INT)bn_add_words&~mask);
    765 		}
    766 	else
    767 		carry = 1;
    768 
    769 	mask  = 0-(PTR_SIZE_INT)(*u.f)(c_d,r_d,_nist_p_384[0],BN_NIST_384_TOP);
    770 	mask &= 0-(PTR_SIZE_INT)carry;
    771 	res   = (BN_ULONG *)(((PTR_SIZE_INT)c_d&~mask) |
    772 	 ((PTR_SIZE_INT)r_d&mask));
    773 	nist_cp_bn(r_d, res, BN_NIST_384_TOP);
    774 	r->top = BN_NIST_384_TOP;
    775 	bn_correct_top(r);
    776 
    777 	return 1;
    778 	}
    779 
    780 #define BN_NIST_521_RSHIFT	(521%BN_BITS2)
    781 #define BN_NIST_521_LSHIFT	(BN_BITS2-BN_NIST_521_RSHIFT)
    782 #define BN_NIST_521_TOP_MASK	((BN_ULONG)BN_MASK2>>BN_NIST_521_LSHIFT)
    783 
    784 int BN_nist_mod_521(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
    785 	BN_CTX *ctx)
    786 	{
    787 	int	top = a->top, i;
    788 	BN_ULONG *r_d, *a_d = a->d,
    789 		 t_d[BN_NIST_521_TOP],
    790 		 val,tmp,*res;
    791 	PTR_SIZE_INT mask;
    792 	static const BIGNUM _bignum_nist_p_521_sqr = {
    793 		(BN_ULONG *)_nist_p_521_sqr,
    794 		sizeof(_nist_p_521_sqr)/sizeof(_nist_p_521_sqr[0]),
    795 		sizeof(_nist_p_521_sqr)/sizeof(_nist_p_521_sqr[0]),
    796 		0,BN_FLG_STATIC_DATA };
    797 
    798 	field = &_bignum_nist_p_521; /* just to make sure */
    799 
    800  	if (BN_is_negative(a) || BN_ucmp(a,&_bignum_nist_p_521_sqr)>=0)
    801 		return BN_nnmod(r, a, field, ctx);
    802 
    803 	i = BN_ucmp(field, a);
    804 	if (i == 0)
    805 		{
    806 		BN_zero(r);
    807 		return 1;
    808 		}
    809 	else if (i > 0)
    810 		return (r == a)? 1 : (BN_copy(r ,a) != NULL);
    811 
    812 	if (r != a)
    813 		{
    814 		if (!bn_wexpand(r,BN_NIST_521_TOP))
    815 			return 0;
    816 		r_d = r->d;
    817 		nist_cp_bn(r_d,a_d, BN_NIST_521_TOP);
    818 		}
    819 	else
    820 		r_d = a_d;
    821 
    822 	/* upper 521 bits, copy ... */
    823 	nist_cp_bn_0(t_d,a_d + (BN_NIST_521_TOP-1), top - (BN_NIST_521_TOP-1),BN_NIST_521_TOP);
    824 	/* ... and right shift */
    825 	for (val=t_d[0],i=0; i<BN_NIST_521_TOP-1; i++)
    826 		{
    827 		tmp = val>>BN_NIST_521_RSHIFT;
    828 		val = t_d[i+1];
    829 		t_d[i] = (tmp | val<<BN_NIST_521_LSHIFT) & BN_MASK2;
    830 		}
    831 	t_d[i] = val>>BN_NIST_521_RSHIFT;
    832 	/* lower 521 bits */
    833 	r_d[i] &= BN_NIST_521_TOP_MASK;
    834 
    835 	bn_add_words(r_d,r_d,t_d,BN_NIST_521_TOP);
    836 	mask = 0-(PTR_SIZE_INT)bn_sub_words(t_d,r_d,_nist_p_521,BN_NIST_521_TOP);
    837 	res  = (BN_ULONG *)(((PTR_SIZE_INT)t_d&~mask) |
    838 	 ((PTR_SIZE_INT)r_d&mask));
    839 	nist_cp_bn(r_d,res,BN_NIST_521_TOP);
    840 	r->top = BN_NIST_521_TOP;
    841 	bn_correct_top(r);
    842 
    843 	return 1;
    844 	}
    845