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security/nss/lib/freebl/ecl/ecp_224.c@6474c204b198

security/nss/lib/freebl/ecl/ecp_224.c

Wed, 31 Dec 2014 06:09:35 +0100

author
Michael Schloh von Bennewitz <michael@schloh.com>
date
Wed, 31 Dec 2014 06:09:35 +0100
changeset 0
6474c204b198
permissions
-rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

     1 /* This Source Code Form is subject to the terms of the Mozilla Public

     2  * License, v. 2.0. If a copy of the MPL was not distributed with this

     3  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

     4 

     5 #include "ecp.h"

     6 #include "mpi.h"

     7 #include "mplogic.h"

     8 #include "mpi-priv.h"

     9 

    10 #define ECP224_DIGITS ECL_CURVE_DIGITS(224)

    11 

    12 /* Fast modular reduction for p224 = 2^224 - 2^96 + 1.  a can be r. Uses

    13  * algorithm 7 from Brown, Hankerson, Lopez, Menezes. Software

    14  * Implementation of the NIST Elliptic Curves over Prime Fields. */

    15 static mp_err

    16 ec_GFp_nistp224_mod(const mp_int *a, mp_int *r, const GFMethod *meth)

    17 {

    18 	mp_err res = MP_OKAY;

    19 	mp_size a_used = MP_USED(a);

    20 

    21 	int    r3b;

    22 	mp_digit carry;

    23 #ifdef ECL_THIRTY_TWO_BIT

    24         mp_digit a6a = 0, a6b = 0,

    25                 a5a = 0, a5b = 0, a4a = 0, a4b = 0, a3a = 0, a3b = 0;

    26         mp_digit r0a, r0b, r1a, r1b, r2a, r2b, r3a;

    27 #else

    28 	mp_digit a6 = 0, a5 = 0, a4 = 0, a3b = 0, a5a = 0;

    29         mp_digit a6b = 0, a6a_a5b = 0, a5b = 0, a5a_a4b = 0, a4a_a3b = 0;

    30         mp_digit r0, r1, r2, r3;

    31 #endif

    32 

    33 	/* reduction not needed if a is not larger than field size */

    34 	if (a_used < ECP224_DIGITS) {

    35 		if (a == r) return MP_OKAY;

    36 		return mp_copy(a, r);

    37 	}

    38 	/* for polynomials larger than twice the field size, use regular

    39 	 * reduction */

    40 	if (a_used > ECL_CURVE_DIGITS(224*2)) {

    41 		MP_CHECKOK(mp_mod(a, &meth->irr, r));

    42 	} else {

    43 #ifdef ECL_THIRTY_TWO_BIT

    44 		/* copy out upper words of a */

    45 		switch (a_used) {

    46 		case 14:

    47 			a6b = MP_DIGIT(a, 13);

    48 		case 13:

    49 			a6a = MP_DIGIT(a, 12);

    50 		case 12:

    51 			a5b = MP_DIGIT(a, 11);

    52 		case 11:

    53 			a5a = MP_DIGIT(a, 10);

    54 		case 10:

    55 			a4b = MP_DIGIT(a, 9);

    56 		case 9:

    57 			a4a = MP_DIGIT(a, 8);

    58 		case 8:

    59 			a3b = MP_DIGIT(a, 7);

    60 		}

    61 		r3a = MP_DIGIT(a, 6);

    62 		r2b= MP_DIGIT(a, 5);

    63 		r2a= MP_DIGIT(a, 4);

    64 		r1b = MP_DIGIT(a, 3);

    65 		r1a = MP_DIGIT(a, 2);

    66 		r0b = MP_DIGIT(a, 1);

    67 		r0a = MP_DIGIT(a, 0);

    68 

    69 

    70 		/* implement r = (a3a,a2,a1,a0)

    71 			+(a5a, a4,a3b,  0)

    72 			+(  0, a6,a5b,  0)

    73 			-(  0	 0,    0|a6b, a6a|a5b )

    74 			-(  a6b, a6a|a5b, a5a|a4b, a4a|a3b ) */

    75 		MP_ADD_CARRY (r1b, a3b, r1b, 0,     carry);

    76 		MP_ADD_CARRY (r2a, a4a, r2a, carry, carry);

    77 		MP_ADD_CARRY (r2b, a4b, r2b, carry, carry);

    78 		MP_ADD_CARRY (r3a, a5a, r3a, carry, carry);

    79 		r3b = carry;

    80 		MP_ADD_CARRY (r1b, a5b, r1b, 0,     carry);

    81 		MP_ADD_CARRY (r2a, a6a, r2a, carry, carry);

    82 		MP_ADD_CARRY (r2b, a6b, r2b, carry, carry);

    83 		MP_ADD_CARRY (r3a,   0, r3a, carry, carry);

    84 		r3b += carry;

    85 		MP_SUB_BORROW(r0a, a3b, r0a, 0,     carry);

    86 		MP_SUB_BORROW(r0b, a4a, r0b, carry, carry);

    87 		MP_SUB_BORROW(r1a, a4b, r1a, carry, carry);

    88 		MP_SUB_BORROW(r1b, a5a, r1b, carry, carry);

    89 		MP_SUB_BORROW(r2a, a5b, r2a, carry, carry);

    90 		MP_SUB_BORROW(r2b, a6a, r2b, carry, carry);

    91 		MP_SUB_BORROW(r3a, a6b, r3a, carry, carry);

    92 		r3b -= carry;

    93 		MP_SUB_BORROW(r0a, a5b, r0a, 0,     carry);

    94 		MP_SUB_BORROW(r0b, a6a, r0b, carry, carry);

    95 		MP_SUB_BORROW(r1a, a6b, r1a, carry, carry);

    96 		if (carry) {

    97 			MP_SUB_BORROW(r1b, 0, r1b, carry, carry);

    98 			MP_SUB_BORROW(r2a, 0, r2a, carry, carry);

    99 			MP_SUB_BORROW(r2b, 0, r2b, carry, carry);

   100 			MP_SUB_BORROW(r3a, 0, r3a, carry, carry);

   101 			r3b -= carry;

   102 		}

   103 

   104 		while (r3b > 0) {

   105 			int tmp;

   106 			MP_ADD_CARRY(r1b, r3b, r1b, 0,     carry);

   107 			if (carry) {

   108 				MP_ADD_CARRY(r2a,  0, r2a, carry, carry);

   109 				MP_ADD_CARRY(r2b,  0, r2b, carry, carry);

   110 				MP_ADD_CARRY(r3a,  0, r3a, carry, carry);

   111 			}

   112 			tmp = carry;

   113 			MP_SUB_BORROW(r0a, r3b, r0a, 0,     carry);

   114 			if (carry) {

   115 				MP_SUB_BORROW(r0b, 0, r0b, carry, carry);

   116 				MP_SUB_BORROW(r1a, 0, r1a, carry, carry);

   117 				MP_SUB_BORROW(r1b, 0, r1b, carry, carry);

   118 				MP_SUB_BORROW(r2a, 0, r2a, carry, carry);

   119 				MP_SUB_BORROW(r2b, 0, r2b, carry, carry);

   120 				MP_SUB_BORROW(r3a, 0, r3a, carry, carry);

   121 				tmp -= carry;

   122 			}

   123 			r3b = tmp;

   124 		}

   125 

   126 		while (r3b < 0) {

   127 			mp_digit maxInt = MP_DIGIT_MAX;

   128                 	MP_ADD_CARRY (r0a, 1, r0a, 0,     carry);

   129                 	MP_ADD_CARRY (r0b, 0, r0b, carry, carry);

   130                 	MP_ADD_CARRY (r1a, 0, r1a, carry, carry);

   131                 	MP_ADD_CARRY (r1b, maxInt, r1b, carry, carry);

   132                 	MP_ADD_CARRY (r2a, maxInt, r2a, carry, carry);

   133                 	MP_ADD_CARRY (r2b, maxInt, r2b, carry, carry);

   134                 	MP_ADD_CARRY (r3a, maxInt, r3a, carry, carry);

   135 			r3b += carry;

   136 		}

   137 		/* check for final reduction */

   138 		/* now the only way we are over is if the top 4 words are all ones */

   139 		if ((r3a == MP_DIGIT_MAX) && (r2b == MP_DIGIT_MAX)

   140 			&& (r2a == MP_DIGIT_MAX) && (r1b == MP_DIGIT_MAX) &&

   141 			 ((r1a != 0) || (r0b != 0) || (r0a != 0)) ) {

   142 			/* one last subraction */

   143 			MP_SUB_BORROW(r0a, 1, r0a, 0,     carry);

   144 			MP_SUB_BORROW(r0b, 0, r0b, carry, carry);

   145 			MP_SUB_BORROW(r1a, 0, r1a, carry, carry);

   146 			r1b = r2a = r2b = r3a = 0;

   147 		}

   148 

   149 

   150 		if (a != r) {

   151 			MP_CHECKOK(s_mp_pad(r, 7));

   152 		}

   153 		/* set the lower words of r */

   154 		MP_SIGN(r) = MP_ZPOS;

   155 		MP_USED(r) = 7;

   156 		MP_DIGIT(r, 6) = r3a;

   157 		MP_DIGIT(r, 5) = r2b;

   158 		MP_DIGIT(r, 4) = r2a;

   159 		MP_DIGIT(r, 3) = r1b;

   160 		MP_DIGIT(r, 2) = r1a;

   161 		MP_DIGIT(r, 1) = r0b;

   162 		MP_DIGIT(r, 0) = r0a;

   163 #else

   164 		/* copy out upper words of a */

   165 		switch (a_used) {

   166 		case 7:

   167 			a6 = MP_DIGIT(a, 6);

   168 			a6b = a6 >> 32;

   169 			a6a_a5b = a6 << 32;

   170 		case 6:

   171 			a5 = MP_DIGIT(a, 5);

   172 			a5b = a5 >> 32;

   173 			a6a_a5b |= a5b;

   174 			a5b = a5b << 32;

   175 			a5a_a4b = a5 << 32;

   176 			a5a = a5 & 0xffffffff;

   177 		case 5:

   178 			a4 = MP_DIGIT(a, 4);

   179 			a5a_a4b |= a4 >> 32;

   180 			a4a_a3b = a4 << 32;

   181 		case 4:

   182 			a3b = MP_DIGIT(a, 3) >> 32;

   183 			a4a_a3b |= a3b;

   184 			a3b = a3b << 32;

   185 		}

   186 

   187 		r3 = MP_DIGIT(a, 3) & 0xffffffff;

   188 		r2 = MP_DIGIT(a, 2);

   189 		r1 = MP_DIGIT(a, 1);

   190 		r0 = MP_DIGIT(a, 0);

   191 

   192 		/* implement r = (a3a,a2,a1,a0)

   193 			+(a5a, a4,a3b,  0)

   194 			+(  0, a6,a5b,  0)

   195 			-(  0	 0,    0|a6b, a6a|a5b )

   196 			-(  a6b, a6a|a5b, a5a|a4b, a4a|a3b ) */

   197 		MP_ADD_CARRY (r1, a3b, r1, 0,     carry);

   198 		MP_ADD_CARRY (r2, a4 , r2, carry, carry);

   199 		MP_ADD_CARRY (r3, a5a, r3, carry, carry);

   200 		MP_ADD_CARRY (r1, a5b, r1, 0,     carry);

   201 		MP_ADD_CARRY (r2, a6 , r2, carry, carry);

   202 		MP_ADD_CARRY (r3,   0, r3, carry, carry);

   203 

   204 		MP_SUB_BORROW(r0, a4a_a3b, r0, 0,     carry);

   205 		MP_SUB_BORROW(r1, a5a_a4b, r1, carry, carry);

   206 		MP_SUB_BORROW(r2, a6a_a5b, r2, carry, carry);

   207 		MP_SUB_BORROW(r3, a6b    , r3, carry, carry);

   208 		MP_SUB_BORROW(r0, a6a_a5b, r0, 0,     carry);

   209 		MP_SUB_BORROW(r1, a6b    , r1, carry, carry);

   210 		if (carry) {

   211 			MP_SUB_BORROW(r2, 0, r2, carry, carry);

   212 			MP_SUB_BORROW(r3, 0, r3, carry, carry);

   213 		}

   214 

   215 

   216 		/* if the value is negative, r3 has a 2's complement 

   217 		 * high value */

   218 		r3b = (int)(r3 >>32);

   219 		while (r3b > 0) {

   220 			r3 &= 0xffffffff;

   221 			MP_ADD_CARRY(r1,((mp_digit)r3b) << 32, r1, 0, carry);

   222 			if (carry) {

   223 				MP_ADD_CARRY(r2,  0, r2, carry, carry);

   224 				MP_ADD_CARRY(r3,  0, r3, carry, carry);

   225 			}

   226 			MP_SUB_BORROW(r0, r3b, r0, 0, carry);

   227 			if (carry) {

   228 				MP_SUB_BORROW(r1, 0, r1, carry, carry);

   229 				MP_SUB_BORROW(r2, 0, r2, carry, carry);

   230 				MP_SUB_BORROW(r3, 0, r3, carry, carry);

   231 			}

   232 			r3b = (int)(r3 >>32);

   233 		}

   234 

   235 		while (r3b < 0) {

   236                 	MP_ADD_CARRY (r0, 1, r0, 0,     carry);

   237                 	MP_ADD_CARRY (r1, MP_DIGIT_MAX <<32, r1, carry, carry);

   238                 	MP_ADD_CARRY (r2, MP_DIGIT_MAX, r2, carry, carry);

   239                 	MP_ADD_CARRY (r3, MP_DIGIT_MAX >> 32, r3, carry, carry);

   240 			r3b = (int)(r3 >>32);

   241 		}

   242 		/* check for final reduction */

   243 		/* now the only way we are over is if the top 4 words are 

   244 		 * all ones. Subtract the curve. (curve is 2^224 - 2^96 +1)

   245 		 */

   246 		if ((r3 == (MP_DIGIT_MAX >> 32)) && (r2 == MP_DIGIT_MAX)

   247 			&& ((r1 & MP_DIGIT_MAX << 32)== MP_DIGIT_MAX << 32) &&

   248 			 ((r1 != MP_DIGIT_MAX << 32 ) || (r0 != 0)) ) {

   249 			/* one last subraction */

   250 			MP_SUB_BORROW(r0, 1, r0, 0,     carry);

   251 			MP_SUB_BORROW(r1, MP_DIGIT_MAX << 32, r1, carry, carry);

   252 			r2 = r3 = 0;

   253 		}

   254 

   255 

   256 		if (a != r) {

   257 			MP_CHECKOK(s_mp_pad(r, 4));

   258 		}

   259 		/* set the lower words of r */

   260 		MP_SIGN(r) = MP_ZPOS;

   261 		MP_USED(r) = 4;

   262 		MP_DIGIT(r, 3) = r3;

   263 		MP_DIGIT(r, 2) = r2;

   264 		MP_DIGIT(r, 1) = r1;

   265 		MP_DIGIT(r, 0) = r0;

   266 #endif

   267 	}

   268 	s_mp_clamp(r);

   269 

   270   CLEANUP:

   271 	return res;

   272 }

   273 

   274 /* Compute the square of polynomial a, reduce modulo p224. Store the

   275  * result in r.  r could be a.  Uses optimized modular reduction for p224. 

   276  */

   277 static mp_err

   278 ec_GFp_nistp224_sqr(const mp_int *a, mp_int *r, const GFMethod *meth)

   279 {

   280 	mp_err res = MP_OKAY;

   281 

   282 	MP_CHECKOK(mp_sqr(a, r));

   283 	MP_CHECKOK(ec_GFp_nistp224_mod(r, r, meth));

   284   CLEANUP:

   285 	return res;

   286 }

   287 

   288 /* Compute the product of two polynomials a and b, reduce modulo p224.

   289  * Store the result in r.  r could be a or b; a could be b.  Uses

   290  * optimized modular reduction for p224. */

   291 static mp_err

   292 ec_GFp_nistp224_mul(const mp_int *a, const mp_int *b, mp_int *r,

   293 					const GFMethod *meth)

   294 {

   295 	mp_err res = MP_OKAY;

   296 

   297 	MP_CHECKOK(mp_mul(a, b, r));

   298 	MP_CHECKOK(ec_GFp_nistp224_mod(r, r, meth));

   299   CLEANUP:

   300 	return res;

   301 }

   302 

   303 /* Divides two field elements. If a is NULL, then returns the inverse of

   304  * b. */

   305 static mp_err

   306 ec_GFp_nistp224_div(const mp_int *a, const mp_int *b, mp_int *r,

   307 		   const GFMethod *meth)

   308 {

   309 	mp_err res = MP_OKAY;

   310 	mp_int t;

   311 

   312 	/* If a is NULL, then return the inverse of b, otherwise return a/b. */

   313 	if (a == NULL) {

   314 		return  mp_invmod(b, &meth->irr, r);

   315 	} else {

   316 		/* MPI doesn't support divmod, so we implement it using invmod and 

   317 		 * mulmod. */

   318 		MP_CHECKOK(mp_init(&t));

   319 		MP_CHECKOK(mp_invmod(b, &meth->irr, &t));

   320 		MP_CHECKOK(mp_mul(a, &t, r));

   321 		MP_CHECKOK(ec_GFp_nistp224_mod(r, r, meth));

   322 	  CLEANUP:

   323 		mp_clear(&t);

   324 		return res;

   325 	}

   326 }

   327 

   328 /* Wire in fast field arithmetic and precomputation of base point for

   329  * named curves. */

   330 mp_err

   331 ec_group_set_gfp224(ECGroup *group, ECCurveName name)

   332 {

   333 	if (name == ECCurve_NIST_P224) {

   334 		group->meth->field_mod = &ec_GFp_nistp224_mod;

   335 		group->meth->field_mul = &ec_GFp_nistp224_mul;

   336 		group->meth->field_sqr = &ec_GFp_nistp224_sqr;

   337 		group->meth->field_div = &ec_GFp_nistp224_div;

   338 	}

   339 	return MP_OKAY;

   340 }

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