vendor/monocypher/src/optional/monocypher-ed25519.c

1// Monocypher version 4.0.3

2//

3// This file is dual-licensed. Choose whichever licence you want from

4// the two licences listed below.

5//

6// The first licence is a regular 2-clause BSD licence. The second licence

7// is the CC-0 from Creative Commons. It is intended to release Monocypher

8// to the public domain. The BSD licence serves as a fallback option.

9//

10// SPDX-License-Identifier: BSD-2-Clause OR CC0-1.0

11//

12// ------------------------------------------------------------------------

13//

16//

17//

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19// modification, are permitted provided that the following conditions are

20// met:

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22// 1. Redistributions of source code must retain the above copyright

23// notice, this list of conditions and the following disclaimer.

24//

25// 2. Redistributions in binary form must reproduce the above copyright

26// notice, this list of conditions and the following disclaimer in the

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28// distribution.

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31// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

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40// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

41//

42// ------------------------------------------------------------------------

43//

44// Written in 2017-2019 by Loup Vaillant

45//

46// To the extent possible under law, the author(s) have dedicated all copyright

47// and related neighboring rights to this software to the public domain

48// worldwide. This software is distributed without any warranty.

49//

50// You should have received a copy of the CC0 Public Domain Dedication along

51// with this software. If not, see

52// <https://creativecommons.org/publicdomain/zero/1.0/>

54#include "monocypher-ed25519.h"

56#ifdef MONOCYPHER_CPP_NAMESPACE

57namespace MONOCYPHER_CPP_NAMESPACE {

58#endif

60/////////////////

61/// Utilities ///

62/////////////////

63#define FOR(i, min, max) for (size_t i = min; i < max; i++)

64#define COPY(dst, src, size) FOR(_i_, 0, size) (dst)[_i_] = (src)[_i_]

65#define ZERO(buf, size) FOR(_i_, 0, size) (buf)[_i_] = 0

66#define WIPE_CTX(ctx) crypto_wipe(ctx , sizeof(*(ctx)))

67#define WIPE_BUFFER(buffer) crypto_wipe(buffer, sizeof(buffer))

68#define MIN(a, b) ((a) <= (b) ? (a) : (b))

69typedef uint8_t u8;

70typedef uint64_t u64;

72// Returns the smallest positive integer y such that

73// (x + y) % pow_2 == 0

74// Basically, it's how many bytes we need to add to "align" x.

75// Only works when pow_2 is a power of 2.

76// Note: we use ~x+1 instead of -x to avoid compiler warnings

77static size_t align(size_t x, size_t pow_2)

78{

79 return (~x + 1) & (pow_2 - 1);

80}

82static u64 load64_be(const u8 s[8])

83{

84 return((u64)s[0] << 56)

85 | ((u64)s[1] << 48)

86 | ((u64)s[2] << 40)

87 | ((u64)s[3] << 32)

88 | ((u64)s[4] << 24)

89 | ((u64)s[5] << 16)

90 | ((u64)s[6] << 8)

91 | (u64)s[7];

92}

94static void store64_be(u8 out[8], u64 in)

95{

96 out[0] = (u8)(in >> 56);

97 out[1] = (u8)(in >> 48);

98 out[2] = (u8)(in >> 40);

99 out[3] = (u8)(in >> 32);

100 out[4] = (u8)(in >> 24);

101 out[5] = (u8)(in >> 16);

102 out[6] = (u8)(in >> 8);

103 out[7] = (u8) in ;

104}

105

106static void load64_be_buf (u64 *dst, const u8 *src, size_t size) {

107 FOR(i, 0, size) { dst[i] = load64_be(src + i*8); }

108}

109

110///////////////

111/// SHA 512 ///

112///////////////

113static u64 rot(u64 x, int c ) { return (x >> c) | (x << (64 - c)); }

114static u64 ch (u64 x, u64 y, u64 z) { return (x & y) ^ (~x & z); }

115static u64 maj(u64 x, u64 y, u64 z) { return (x & y) ^ ( x & z) ^ (y & z); }

116static u64 big_sigma0(u64 x) { return rot(x, 28) ^ rot(x, 34) ^ rot(x, 39); }

117static u64 big_sigma1(u64 x) { return rot(x, 14) ^ rot(x, 18) ^ rot(x, 41); }

118static u64 lit_sigma0(u64 x) { return rot(x, 1) ^ rot(x, 8) ^ (x >> 7); }

119static u64 lit_sigma1(u64 x) { return rot(x, 19) ^ rot(x, 61) ^ (x >> 6); }

120

121static const u64 K[80] = {

122 0x428a2f98d728ae22,0x7137449123ef65cd,0xb5c0fbcfec4d3b2f,0xe9b5dba58189dbbc,

123 0x3956c25bf348b538,0x59f111f1b605d019,0x923f82a4af194f9b,0xab1c5ed5da6d8118,

124 0xd807aa98a3030242,0x12835b0145706fbe,0x243185be4ee4b28c,0x550c7dc3d5ffb4e2,

125 0x72be5d74f27b896f,0x80deb1fe3b1696b1,0x9bdc06a725c71235,0xc19bf174cf692694,

126 0xe49b69c19ef14ad2,0xefbe4786384f25e3,0x0fc19dc68b8cd5b5,0x240ca1cc77ac9c65,

127 0x2de92c6f592b0275,0x4a7484aa6ea6e483,0x5cb0a9dcbd41fbd4,0x76f988da831153b5,

128 0x983e5152ee66dfab,0xa831c66d2db43210,0xb00327c898fb213f,0xbf597fc7beef0ee4,

129 0xc6e00bf33da88fc2,0xd5a79147930aa725,0x06ca6351e003826f,0x142929670a0e6e70,

130 0x27b70a8546d22ffc,0x2e1b21385c26c926,0x4d2c6dfc5ac42aed,0x53380d139d95b3df,

131 0x650a73548baf63de,0x766a0abb3c77b2a8,0x81c2c92e47edaee6,0x92722c851482353b,

132 0xa2bfe8a14cf10364,0xa81a664bbc423001,0xc24b8b70d0f89791,0xc76c51a30654be30,

133 0xd192e819d6ef5218,0xd69906245565a910,0xf40e35855771202a,0x106aa07032bbd1b8,

134 0x19a4c116b8d2d0c8,0x1e376c085141ab53,0x2748774cdf8eeb99,0x34b0bcb5e19b48a8,

135 0x391c0cb3c5c95a63,0x4ed8aa4ae3418acb,0x5b9cca4f7763e373,0x682e6ff3d6b2b8a3,

136 0x748f82ee5defb2fc,0x78a5636f43172f60,0x84c87814a1f0ab72,0x8cc702081a6439ec,

137 0x90befffa23631e28,0xa4506cebde82bde9,0xbef9a3f7b2c67915,0xc67178f2e372532b,

138 0xca273eceea26619c,0xd186b8c721c0c207,0xeada7dd6cde0eb1e,0xf57d4f7fee6ed178,

139 0x06f067aa72176fba,0x0a637dc5a2c898a6,0x113f9804bef90dae,0x1b710b35131c471b,

140 0x28db77f523047d84,0x32caab7b40c72493,0x3c9ebe0a15c9bebc,0x431d67c49c100d4c,

141 0x4cc5d4becb3e42b6,0x597f299cfc657e2a,0x5fcb6fab3ad6faec,0x6c44198c4a475817

142};

143

144static void sha512_compress(crypto_sha512_ctx *ctx)

145{

146 u64 a = ctx->hash[0]; u64 b = ctx->hash[1];

147 u64 c = ctx->hash[2]; u64 d = ctx->hash[3];

148 u64 e = ctx->hash[4]; u64 f = ctx->hash[5];

149 u64 g = ctx->hash[6]; u64 h = ctx->hash[7];

150

151 FOR (j, 0, 16) {

152 u64 in = K[j] + ctx->input[j];

153 u64 t1 = big_sigma1(e) + ch (e, f, g) + h + in;

154 u64 t2 = big_sigma0(a) + maj(a, b, c);

155 h = g; g = f; f = e; e = d + t1;

156 d = c; c = b; b = a; a = t1 + t2;

157 }

158 size_t i16 = 0;

159 FOR(i, 1, 5) {

160 i16 += 16;

161 FOR (j, 0, 16) {

162 ctx->input[j] += lit_sigma1(ctx->input[(j- 2) & 15]);

163 ctx->input[j] += lit_sigma0(ctx->input[(j-15) & 15]);

164 ctx->input[j] += ctx->input[(j- 7) & 15];

165 u64 in = K[i16 + j] + ctx->input[j];

166 u64 t1 = big_sigma1(e) + ch (e, f, g) + h + in;

167 u64 t2 = big_sigma0(a) + maj(a, b, c);

168 h = g; g = f; f = e; e = d + t1;

169 d = c; c = b; b = a; a = t1 + t2;

170 }

171 }

172

173 ctx->hash[0] += a; ctx->hash[1] += b;

174 ctx->hash[2] += c; ctx->hash[3] += d;

175 ctx->hash[4] += e; ctx->hash[5] += f;

176 ctx->hash[6] += g; ctx->hash[7] += h;

177}

178

179// Write 1 input byte

180static void sha512_set_input(crypto_sha512_ctx *ctx, u8 input)

181{

182 size_t word = ctx->input_idx >> 3;

183 size_t byte = ctx->input_idx & 7;

184 ctx->input[word] |= (u64)input << (8 * (7 - byte));

185}

186

187// Increment a 128-bit "word".

188static void sha512_incr(u64 x[2], u64 y)

189{

190 x[1] += y;

191 if (x[1] < y) {

192 x[0]++;

193 }

194}

195

196void crypto_sha512_init(crypto_sha512_ctx *ctx)

197{

198 ctx->hash[0] = 0x6a09e667f3bcc908;

199 ctx->hash[1] = 0xbb67ae8584caa73b;

200 ctx->hash[2] = 0x3c6ef372fe94f82b;

201 ctx->hash[3] = 0xa54ff53a5f1d36f1;

202 ctx->hash[4] = 0x510e527fade682d1;

203 ctx->hash[5] = 0x9b05688c2b3e6c1f;

204 ctx->hash[6] = 0x1f83d9abfb41bd6b;

205 ctx->hash[7] = 0x5be0cd19137e2179;

206 ctx->input_size[0] = 0;

207 ctx->input_size[1] = 0;

208 ctx->input_idx = 0;

209 ZERO(ctx->input, 16);

210}

211

212void crypto_sha512_update(crypto_sha512_ctx *ctx,

213 const u8 *message, size_t message_size)

214{

215 // Avoid undefined NULL pointer increments with empty messages

216 if (message_size == 0) {

217 return;

218 }

219

220 // Align ourselves with word boundaries

221 if ((ctx->input_idx & 7) != 0) {

222 size_t nb_bytes = MIN(align(ctx->input_idx, 8), message_size);

223 FOR (i, 0, nb_bytes) {

224 sha512_set_input(ctx, message[i]);

225 ctx->input_idx++;

226 }

227 message += nb_bytes;

228 message_size -= nb_bytes;

229 }

230

231 // Align ourselves with block boundaries

232 if ((ctx->input_idx & 127) != 0) {

233 size_t nb_words = MIN(align(ctx->input_idx, 128), message_size) >> 3;

234 load64_be_buf(ctx->input + (ctx->input_idx >> 3), message, nb_words);

235 ctx->input_idx += nb_words << 3;

236 message += nb_words << 3;

237 message_size -= nb_words << 3;

238 }

239

240 // Compress block if needed

241 if (ctx->input_idx == 128) {

242 sha512_incr(ctx->input_size, 1024); // size is in bits

243 sha512_compress(ctx);

244 ctx->input_idx = 0;

245 ZERO(ctx->input, 16);

246 }

247

248 // Process the message block by block

249 FOR (i, 0, message_size >> 7) { // number of blocks

250 load64_be_buf(ctx->input, message, 16);

251 sha512_incr(ctx->input_size, 1024); // size is in bits

252 sha512_compress(ctx);

253 ctx->input_idx = 0;

254 ZERO(ctx->input, 16);

255 message += 128;

256 }

257 message_size &= 127;

258

259 if (message_size != 0) {

260 // Remaining words

261 size_t nb_words = message_size >> 3;

262 load64_be_buf(ctx->input, message, nb_words);

263 ctx->input_idx += nb_words << 3;

264 message += nb_words << 3;

265 message_size -= nb_words << 3;

266

267 // Remaining bytes

268 FOR (i, 0, message_size) {

269 sha512_set_input(ctx, message[i]);

270 ctx->input_idx++;

271 }

272 }

273}

274

275void crypto_sha512_final(crypto_sha512_ctx *ctx, u8 hash[64])

276{

277 // Add padding bit

278 if (ctx->input_idx == 0) {

279 ZERO(ctx->input, 16);

280 }

281 sha512_set_input(ctx, 128);

282

283 // Update size

284 sha512_incr(ctx->input_size, ctx->input_idx * 8);

285

286 // Compress penultimate block (if any)

287 if (ctx->input_idx > 111) {

288 sha512_compress(ctx);

289 ZERO(ctx->input, 14);

290 }

291 // Compress last block

292 ctx->input[14] = ctx->input_size[0];

293 ctx->input[15] = ctx->input_size[1];

294 sha512_compress(ctx);

295

296 // Copy hash to output (big endian)

297 FOR (i, 0, 8) {

298 store64_be(hash + i*8, ctx->hash[i]);

299 }

300

301 WIPE_CTX(ctx);

302}

303

304void crypto_sha512(u8 hash[64], const u8 *message, size_t message_size)

305{

306 crypto_sha512_ctx ctx;

307 crypto_sha512_init (&ctx);

308 crypto_sha512_update(&ctx, message, message_size);

309 crypto_sha512_final (&ctx, hash);

310}

311

312////////////////////

313/// HMAC SHA 512 ///

314////////////////////

315void crypto_sha512_hmac_init(crypto_sha512_hmac_ctx *ctx,

316 const u8 *key, size_t key_size)

317{

318 // hash key if it is too long

319 if (key_size > 128) {

320 crypto_sha512(ctx->key, key, key_size);

321 key = ctx->key;

322 key_size = 64;

323 }

324 // Compute inner key: padded key XOR 0x36

325 FOR (i, 0, key_size) { ctx->key[i] = key[i] ^ 0x36; }

326 FOR (i, key_size, 128) { ctx->key[i] = 0x36; }

327 // Start computing inner hash

328 crypto_sha512_init (&ctx->ctx);

329 crypto_sha512_update(&ctx->ctx, ctx->key, 128);

330}

331

332void crypto_sha512_hmac_update(crypto_sha512_hmac_ctx *ctx,

333 const u8 *message, size_t message_size)

334{

335 crypto_sha512_update(&ctx->ctx, message, message_size);

336}

337

338void crypto_sha512_hmac_final(crypto_sha512_hmac_ctx *ctx, u8 hmac[64])

339{

340 // Finish computing inner hash

341 crypto_sha512_final(&ctx->ctx, hmac);

342 // Compute outer key: padded key XOR 0x5c

343 FOR (i, 0, 128) {

344 ctx->key[i] ^= 0x36 ^ 0x5c;

345 }

346 // Compute outer hash

347 crypto_sha512_init (&ctx->ctx);

348 crypto_sha512_update(&ctx->ctx, ctx->key , 128);

349 crypto_sha512_update(&ctx->ctx, hmac, 64);

350 crypto_sha512_final (&ctx->ctx, hmac); // outer hash

351 WIPE_CTX(ctx);

352}

353

354void crypto_sha512_hmac(u8 hmac[64], const u8 *key, size_t key_size,

355 const u8 *message, size_t message_size)

356{

357 crypto_sha512_hmac_ctx ctx;

358 crypto_sha512_hmac_init (&ctx, key, key_size);

359 crypto_sha512_hmac_update(&ctx, message, message_size);

360 crypto_sha512_hmac_final (&ctx, hmac);

361}

362

363////////////////////

364/// HKDF SHA 512 ///

365////////////////////

366void crypto_sha512_hkdf_expand(u8 *okm, size_t okm_size,

367 const u8 *prk, size_t prk_size,

368 const u8 *info, size_t info_size)

369{

370 int not_first = 0;

371 u8 ctr = 1;

372 u8 blk[64];

373

374 while (okm_size > 0) {

375 size_t out_size = MIN(okm_size, sizeof(blk));

376

377 crypto_sha512_hmac_ctx ctx;

378 crypto_sha512_hmac_init(&ctx, prk , prk_size);

379 if (not_first) {

380 // For some reason HKDF uses some kind of CBC mode.

381 // For some reason CTR mode alone wasn't enough.

382 // Like what, they didn't trust HMAC in 2010? Really??

383 crypto_sha512_hmac_update(&ctx, blk , sizeof(blk));

384 }

385 crypto_sha512_hmac_update(&ctx, info, info_size);

386 crypto_sha512_hmac_update(&ctx, &ctr, 1);

387 crypto_sha512_hmac_final(&ctx, blk);

388

389 COPY(okm, blk, out_size);

390

391 not_first = 1;

392 okm += out_size;

393 okm_size -= out_size;

394 ctr++;

395 }

396 WIPE_BUFFER(blk);

397}

398

399void crypto_sha512_hkdf(u8 *okm , size_t okm_size,

400 const u8 *ikm , size_t ikm_size,

401 const u8 *salt, size_t salt_size,

402 const u8 *info, size_t info_size)

403{

404 // Extract

405 u8 prk[64];

406 crypto_sha512_hmac(prk, salt, salt_size, ikm, ikm_size);

407

408 // Expand

409 crypto_sha512_hkdf_expand(okm, okm_size, prk, sizeof(prk), info, info_size);

410

411 WIPE_BUFFER(prk);

412}

413

414///////////////

415/// Ed25519 ///

416///////////////

417void crypto_ed25519_key_pair(u8 secret_key[64], u8 public_key[32], u8 seed[32])

418{

419 u8 a[64];

420 COPY(a, seed, 32); // a[ 0..31] = seed

421 crypto_wipe(seed, 32);

422 COPY(secret_key, a, 32); // secret key = seed

423 crypto_sha512(a, a, 32); // a[ 0..31] = scalar

424 crypto_eddsa_trim_scalar(a, a); // a[ 0..31] = trimmed scalar

425 crypto_eddsa_scalarbase(public_key, a); // public key = [trimmed scalar]B

426 COPY(secret_key + 32, public_key, 32); // secret key includes public half

427 WIPE_BUFFER(a);

428}

429

430static void hash_reduce(u8 h[32],

431 const u8 *a, size_t a_size,

432 const u8 *b, size_t b_size,

433 const u8 *c, size_t c_size,

434 const u8 *d, size_t d_size)

435{

436 u8 hash[64];

437 crypto_sha512_ctx ctx;

438 crypto_sha512_init (&ctx);

439 crypto_sha512_update(&ctx, a, a_size);

440 crypto_sha512_update(&ctx, b, b_size);

441 crypto_sha512_update(&ctx, c, c_size);

442 crypto_sha512_update(&ctx, d, d_size);

443 crypto_sha512_final (&ctx, hash);

444 crypto_eddsa_reduce(h, hash);

445}

446

447static void ed25519_dom_sign(u8 signature[64], const u8 secret_key[64],

448 const u8 *dom, size_t dom_size,

449 const u8 *message, size_t message_size)

450{

451 u8 a[64]; // secret scalar and prefix

452 u8 r[32]; // secret deterministic "random" nonce

453 u8 h[32]; // publically verifiable hash of the message (not wiped)

454 u8 R[32]; // first half of the signature (allows overlapping inputs)

455 const u8 *pk = secret_key + 32;

456

457 crypto_sha512(a, secret_key, 32);

458 crypto_eddsa_trim_scalar(a, a);

459 hash_reduce(r, dom, dom_size, a + 32, 32, message, message_size, 0, 0);

460 crypto_eddsa_scalarbase(R, r);

461 hash_reduce(h, dom, dom_size, R, 32, pk, 32, message, message_size);

462 COPY(signature, R, 32);

463 crypto_eddsa_mul_add(signature + 32, h, a, r);

464

465 WIPE_BUFFER(a);

466 WIPE_BUFFER(r);

467}

468

469void crypto_ed25519_sign(u8 signature [64], const u8 secret_key[64],

470 const u8 *message, size_t message_size)

471{

472 ed25519_dom_sign(signature, secret_key, 0, 0, message, message_size);

473}

474

475int crypto_ed25519_check(const u8 signature[64], const u8 public_key[32],

476 const u8 *msg, size_t msg_size)

477{

478 u8 h_ram[32];

479 hash_reduce(h_ram, signature, 32, public_key, 32, msg, msg_size, 0, 0);

480 return crypto_eddsa_check_equation(signature, public_key, h_ram);

481}

482

483static const u8 domain[34] = "SigEd25519 no Ed25519 collisions\1";

484

485void crypto_ed25519_ph_sign(uint8_t signature[64], const uint8_t secret_key[64],

486 const uint8_t message_hash[64])

487{

488 ed25519_dom_sign(signature, secret_key, domain, sizeof(domain),

489 message_hash, 64);

490}

491

492int crypto_ed25519_ph_check(const uint8_t sig[64], const uint8_t pk[32],

493 const uint8_t msg_hash[64])

494{

495 u8 h_ram[32];

496 hash_reduce(h_ram, domain, sizeof(domain), sig, 32, pk, 32, msg_hash, 64);

497 return crypto_eddsa_check_equation(sig, pk, h_ram);

498}

499

500

501#ifdef MONOCYPHER_CPP_NAMESPACE

502}

503#endif