nss/lib/freebl/ecl/ecp_aff.c - Issue 2078763002: Delete bundled copy of NSS and replace with README.

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Issue 2078763002: Delete bundled copy of NSS and replace with README. (Closed) Base URL: https://chromium.googlesource.com/chromium/deps/nss@master

Patch Set: Delete bundled copy of NSS and replace with README. Created 4 years, 6 months ago

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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 "mplogic.h"

7 #include <stdlib.h>

8

9 /* Checks if point P(px, py) is at infinity. Uses affine coordinates. */

10 mp_err

11 ec_GFp_pt_is_inf_aff(const mp_int px, const mp_int py)

12 {

13

14 if ((mp_cmp_z(px) == 0) && (mp_cmp_z(py) == 0)) {

15 return MP_YES;

16 } else {

17 return MP_NO;

18 }

19

20 }

21

22 /* Sets P(px, py) to be the point at infinity. Uses affine coordinates. */

23 mp_err

24 ec_GFp_pt_set_inf_aff(mp_int px, mp_int py)

25 {

26 mp_zero(px);

27 mp_zero(py);

28 return MP_OKAY;

29 }

30

31 /* Computes R = P + Q based on IEEE P1363 A.10.1. Elliptic curve points P,

32 * Q, and R can all be identical. Uses affine coordinates. Assumes input

33 * is already field-encoded using field_enc, and returns output that is

34 * still field-encoded. */

35 mp_err

36 ec_GFp_pt_add_aff(const mp_int px, const mp_int py, const mp_int *qx,

37 const mp_int qy, mp_int rx, mp_int *ry,

38 const ECGroup *group)

39 {

40 mp_err res = MP_OKAY;

41 mp_int lambda, temp, tempx, tempy;

42

43 MP_DIGITS(&lambda) = 0;

44 MP_DIGITS(&temp) = 0;

45 MP_DIGITS(&tempx) = 0;

46 MP_DIGITS(&tempy) = 0;

47 MP_CHECKOK(mp_init(&lambda));

48 MP_CHECKOK(mp_init(&temp));

49 MP_CHECKOK(mp_init(&tempx));

50 MP_CHECKOK(mp_init(&tempy));

51 /* if P = inf, then R = Q */

52 if (ec_GFp_pt_is_inf_aff(px, py) == 0) {

53 MP_CHECKOK(mp_copy(qx, rx));

54 MP_CHECKOK(mp_copy(qy, ry));

55 res = MP_OKAY;

56 goto CLEANUP;

57 }

58 /* if Q = inf, then R = P */

59 if (ec_GFp_pt_is_inf_aff(qx, qy) == 0) {

60 MP_CHECKOK(mp_copy(px, rx));

61 MP_CHECKOK(mp_copy(py, ry));

62 res = MP_OKAY;

63 goto CLEANUP;

64 }

65 /* if px != qx, then lambda = (py-qy) / (px-qx) */

66 if (mp_cmp(px, qx) != 0) {

67 MP_CHECKOK(group->meth->field_sub(py, qy, &tempy, group->meth));

68 MP_CHECKOK(group->meth->field_sub(px, qx, &tempx, group->meth));

69 MP_CHECKOK(group->meth->

70 field_div(&tempy, &tempx, &lambda, group->met h));

71 } else {

72 /* if py != qy or qy = 0, then R = inf */

73 if (((mp_cmp(py, qy) != 0)) \|\| (mp_cmp_z(qy) == 0)) {

74 mp_zero(rx);

75 mp_zero(ry);

76 res = MP_OKAY;

77 goto CLEANUP;

78 }

79 /* lambda = (3qx^2+a) / (2qy) */

80 MP_CHECKOK(group->meth->field_sqr(qx, &tempx, group->meth));

81 MP_CHECKOK(mp_set_int(&temp, 3));

82 if (group->meth->field_enc) {

83 MP_CHECKOK(group->meth->field_enc(&temp, &temp, group->m eth));

84 }

85 MP_CHECKOK(group->meth->

86 field_mul(&tempx, &temp, &tempx, group->meth) );

87 MP_CHECKOK(group->meth->

88 field_add(&tempx, &group->curvea, &tempx, gro up->meth));

89 MP_CHECKOK(mp_set_int(&temp, 2));

90 if (group->meth->field_enc) {

91 MP_CHECKOK(group->meth->field_enc(&temp, &temp, group->m eth));

92 }

93 MP_CHECKOK(group->meth->field_mul(qy, &temp, &tempy, group->meth ));

94 MP_CHECKOK(group->meth->

95 field_div(&tempx, &tempy, &lambda, group->met h));

96 }

97 /* rx = lambda^2 - px - qx */

98 MP_CHECKOK(group->meth->field_sqr(&lambda, &tempx, group->meth));

99 MP_CHECKOK(group->meth->field_sub(&tempx, px, &tempx, group->meth));

100 MP_CHECKOK(group->meth->field_sub(&tempx, qx, &tempx, group->meth));

101 /* ry = (x1-x2) * lambda - y1 */

102 MP_CHECKOK(group->meth->field_sub(qx, &tempx, &tempy, group->meth));

103 MP_CHECKOK(group->meth->

104 field_mul(&tempy, &lambda, &tempy, group->meth));

105 MP_CHECKOK(group->meth->field_sub(&tempy, qy, &tempy, group->meth));

106 MP_CHECKOK(mp_copy(&tempx, rx));

107 MP_CHECKOK(mp_copy(&tempy, ry));

108

109 CLEANUP:

110 mp_clear(&lambda);

111 mp_clear(&temp);

112 mp_clear(&tempx);

113 mp_clear(&tempy);

114 return res;

115 }

116

117 /* Computes R = P - Q. Elliptic curve points P, Q, and R can all be

118 * identical. Uses affine coordinates. Assumes input is already

119 * field-encoded using field_enc, and returns output that is still

120 * field-encoded. */

121 mp_err

122 ec_GFp_pt_sub_aff(const mp_int px, const mp_int py, const mp_int *qx,

123 const mp_int qy, mp_int rx, mp_int *ry,

124 const ECGroup *group)

125 {

126 mp_err res = MP_OKAY;

127 mp_int nqy;

128

129 MP_DIGITS(&nqy) = 0;

130 MP_CHECKOK(mp_init(&nqy));

131 /* nqy = -qy */

132 MP_CHECKOK(group->meth->field_neg(qy, &nqy, group->meth));

133 res = group->point_add(px, py, qx, &nqy, rx, ry, group);

134 CLEANUP:

135 mp_clear(&nqy);

136 return res;

137 }

138

139 /* Computes R = 2P. Elliptic curve points P and R can be identical. Uses

140 * affine coordinates. Assumes input is already field-encoded using

141 * field_enc, and returns output that is still field-encoded. */

142 mp_err

143 ec_GFp_pt_dbl_aff(const mp_int px, const mp_int py, mp_int *rx,

144 mp_int ry, const ECGroup group)

145 {

146 return ec_GFp_pt_add_aff(px, py, px, py, rx, ry, group);

147 }

148

149 /* by default, this routine is unused and thus doesn't need to be compiled */

150 #ifdef ECL_ENABLE_GFP_PT_MUL_AFF

151 /* Computes R = nP based on IEEE P1363 A.10.3. Elliptic curve points P and

152 * R can be identical. Uses affine coordinates. Assumes input is already

153 * field-encoded using field_enc, and returns output that is still

154 * field-encoded. */

155 mp_err

156 ec_GFp_pt_mul_aff(const mp_int n, const mp_int px, const mp_int *py,

157 mp_int rx, mp_int ry, const ECGroup *group)

158 {

159 mp_err res = MP_OKAY;

160 mp_int k, k3, qx, qy, sx, sy;

161 int b1, b3, i, l;

162

163 MP_DIGITS(&k) = 0;

164 MP_DIGITS(&k3) = 0;

165 MP_DIGITS(&qx) = 0;

166 MP_DIGITS(&qy) = 0;

167 MP_DIGITS(&sx) = 0;

168 MP_DIGITS(&sy) = 0;

169 MP_CHECKOK(mp_init(&k));

170 MP_CHECKOK(mp_init(&k3));

171 MP_CHECKOK(mp_init(&qx));

172 MP_CHECKOK(mp_init(&qy));

173 MP_CHECKOK(mp_init(&sx));

174 MP_CHECKOK(mp_init(&sy));

175

176 /* if n = 0 then r = inf */

177 if (mp_cmp_z(n) == 0) {

178 mp_zero(rx);

179 mp_zero(ry);

180 res = MP_OKAY;

181 goto CLEANUP;

182 }

183 /* Q = P, k = n */

184 MP_CHECKOK(mp_copy(px, &qx));

185 MP_CHECKOK(mp_copy(py, &qy));

186 MP_CHECKOK(mp_copy(n, &k));

187 /* if n < 0 then Q = -Q, k = -k */

188 if (mp_cmp_z(n) < 0) {

189 MP_CHECKOK(group->meth->field_neg(&qy, &qy, group->meth));

190 MP_CHECKOK(mp_neg(&k, &k));

191 }

192 #ifdef ECL_DEBUG /* basic double and add method * /

193 l = mpl_significant_bits(&k) - 1;

194 MP_CHECKOK(mp_copy(&qx, &sx));

195 MP_CHECKOK(mp_copy(&qy, &sy));

196 for (i = l - 1; i >= 0; i--) {

197 /* S = 2S */

198 MP_CHECKOK(group->point_dbl(&sx, &sy, &sx, &sy, group));

199 /* if k_i = 1, then S = S + Q */

200 if (mpl_get_bit(&k, i) != 0) {

201 MP_CHECKOK(group->

202 point_add(&sx, &sy, &qx, &qy, &sx, &s y, group));

203 }

204 }

205 #else /* double and add/subtra ct method from

206 * standard */

207 /* k3 = 3 * k */

208 MP_CHECKOK(mp_set_int(&k3, 3));

209 MP_CHECKOK(mp_mul(&k, &k3, &k3));

210 /* S = Q */

211 MP_CHECKOK(mp_copy(&qx, &sx));

212 MP_CHECKOK(mp_copy(&qy, &sy));

213 /* l = index of high order bit in binary representation of 3k /

214 l = mpl_significant_bits(&k3) - 1;

215 /* for i = l-1 downto 1 */

216 for (i = l - 1; i >= 1; i--) {

217 /* S = 2S */

218 MP_CHECKOK(group->point_dbl(&sx, &sy, &sx, &sy, group));

219 b3 = MP_GET_BIT(&k3, i);

220 b1 = MP_GET_BIT(&k, i);

221 /* if k3_i = 1 and k_i = 0, then S = S + Q */

222 if ((b3 == 1) && (b1 == 0)) {

223 MP_CHECKOK(group->

224 point_add(&sx, &sy, &qx, &qy, &sx, &s y, group));

225 /* if k3_i = 0 and k_i = 1, then S = S - Q */

226 } else if ((b3 == 0) && (b1 == 1)) {

227 MP_CHECKOK(group->

228 point_sub(&sx, &sy, &qx, &qy, &sx, &s y, group));

229 }

230 }

231 #endif

232 /* output S */

233 MP_CHECKOK(mp_copy(&sx, rx));

234 MP_CHECKOK(mp_copy(&sy, ry));

235

236 CLEANUP:

237 mp_clear(&k);

238 mp_clear(&k3);

239 mp_clear(&qx);

240 mp_clear(&qy);

241 mp_clear(&sx);

242 mp_clear(&sy);

243 return res;

244 }

245 #endif

246

247 /* Validates a point on a GFp curve. */

248 mp_err

249 ec_GFp_validate_point(const mp_int px, const mp_int py, const ECGroup *group)

250 {

251 mp_err res = MP_NO;

252 mp_int accl, accr, tmp, pxt, pyt;

253

254 MP_DIGITS(&accl) = 0;

255 MP_DIGITS(&accr) = 0;

256 MP_DIGITS(&tmp) = 0;

257 MP_DIGITS(&pxt) = 0;

258 MP_DIGITS(&pyt) = 0;

259 MP_CHECKOK(mp_init(&accl));

260 MP_CHECKOK(mp_init(&accr));

261 MP_CHECKOK(mp_init(&tmp));

262 MP_CHECKOK(mp_init(&pxt));

263 MP_CHECKOK(mp_init(&pyt));

264

265 /* 1: Verify that publicValue is not the point at infinity */

266 if (ec_GFp_pt_is_inf_aff(px, py) == MP_YES) {

267 res = MP_NO;

268 goto CLEANUP;

269 }

270 /* 2: Verify that the coordinates of publicValue are elements

271 * of the field.

272 */

273 if ((MP_SIGN(px) == MP_NEG) \|\| (mp_cmp(px, &group->meth->irr) >= 0) \|\|

274 (MP_SIGN(py) == MP_NEG) \|\| (mp_cmp(py, &group->meth->irr) >= 0)) {

275 res = MP_NO;

276 goto CLEANUP;

277 }

278 /* 3: Verify that publicValue is on the curve. */

279 if (group->meth->field_enc) {

280 group->meth->field_enc(px, &pxt, group->meth);

281 group->meth->field_enc(py, &pyt, group->meth);

282 } else {

283 MP_CHECKOK( mp_copy(px, &pxt) );

284 MP_CHECKOK( mp_copy(py, &pyt) );

285 }

286 /* left-hand side: y^2 */

287 MP_CHECKOK( group->meth->field_sqr(&pyt, &accl, group->meth) );

288 /* right-hand side: x^3 + ax + b = (x^2 + a)x + b by Horner's rule */

289 MP_CHECKOK( group->meth->field_sqr(&pxt, &tmp, group->meth) );

290 MP_CHECKOK( group->meth->field_add(&tmp, &group->curvea, &tmp, group->me th) );

291 MP_CHECKOK( group->meth->field_mul(&tmp, &pxt, &accr, group->meth) );

292 MP_CHECKOK( group->meth->field_add(&accr, &group->curveb, &accr, group-> meth) );

293 /* check LHS - RHS == 0 */

294 MP_CHECKOK( group->meth->field_sub(&accl, &accr, &accr, group->meth) );

295 if (mp_cmp_z(&accr) != 0) {

296 res = MP_NO;

297 goto CLEANUP;

298 }

299 /* 4: Verify that the order of the curve times the publicValue

300 * is the point at infinity.

301 */

302 MP_CHECKOK( ECPoint_mul(group, &group->order, px, py, &pxt, &pyt) );

303 if (ec_GFp_pt_is_inf_aff(&pxt, &pyt) != MP_YES) {

304 res = MP_NO;

305 goto CLEANUP;

306 }

307

308 res = MP_YES;

309

310 CLEANUP:

311 mp_clear(&accl);

312 mp_clear(&accr);

313 mp_clear(&tmp);

314 mp_clear(&pxt);

315 mp_clear(&pyt);

316 return res;

317 }

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