lib/crypto/curve25519-hacl64.c

   1 // SPDX-License-Identifier: GPL-2.0 OR MIT
   2 /*
   3  * Copyright (C) 2016-2017 INRIA and Microsoft Corporation.
   4  * Copyright (C) 2018-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
   5  *
   6  * This is a machine-generated formally verified implementation of Curve25519
   7  * ECDH from: <https://github.com/mitls/hacl-star>. Though originally machine
   8  * generated, it has been tweaked to be suitable for use in the kernel. It is
   9  * optimized for 64-bit machines that can efficiently work with 128-bit
  10  * integer types.
  11  */
  12
  13 #include <asm/unaligned.h>
  14 #include <crypto/curve25519.h>
  15 #include <linux/string.h>
  16
  17 static __always_inline u64 u64_eq_mask(u64 a, u64 b)
  18 {
  19         u64 x = a ^ b;
  20         u64 minus_x = ~x + (u64)1U;
  21         u64 x_or_minus_x = x | minus_x;
  22         u64 xnx = x_or_minus_x >> (u32)63U;
  23         u64 c = xnx - (u64)1U;
  24         return c;
  25 }
  26
  27 static __always_inline u64 u64_gte_mask(u64 a, u64 b)
  28 {
  29         u64 x = a;
  30         u64 y = b;
  31         u64 x_xor_y = x ^ y;
  32         u64 x_sub_y = x - y;
  33         u64 x_sub_y_xor_y = x_sub_y ^ y;
  34         u64 q = x_xor_y | x_sub_y_xor_y;
  35         u64 x_xor_q = x ^ q;
  36         u64 x_xor_q_ = x_xor_q >> (u32)63U;
  37         u64 c = x_xor_q_ - (u64)1U;
  38         return c;
  39 }
  40
  41 static __always_inline void modulo_carry_top(u64 *b)
  42 {
  43         u64 b4 = b[4];
  44         u64 b0 = b[0];
  45         u64 b4_ = b4 & 0x7ffffffffffffLLU;
  46         u64 b0_ = b0 + 19 * (b4 >> 51);
  47         b[4] = b4_;
  48         b[0] = b0_;
  49 }
  50
  51 static __always_inline void fproduct_copy_from_wide_(u64 *output, u128 *input)
  52 {
  53         {
  54                 u128 xi = input[0];
  55                 output[0] = ((u64)(xi));
  56         }
  57         {
  58                 u128 xi = input[1];
  59                 output[1] = ((u64)(xi));
  60         }
  61         {
  62                 u128 xi = input[2];
  63                 output[2] = ((u64)(xi));
  64         }
  65         {
  66                 u128 xi = input[3];
  67                 output[3] = ((u64)(xi));
  68         }
  69         {
  70                 u128 xi = input[4];
  71                 output[4] = ((u64)(xi));
  72         }
  73 }
  74
  75 static __always_inline void
  76 fproduct_sum_scalar_multiplication_(u128 *output, u64 *input, u64 s)
  77 {
  78         output[0] += (u128)input[0] * s;
  79         output[1] += (u128)input[1] * s;
  80         output[2] += (u128)input[2] * s;
  81         output[3] += (u128)input[3] * s;
  82         output[4] += (u128)input[4] * s;
  83 }
  84
  85 static __always_inline void fproduct_carry_wide_(u128 *tmp)
  86 {
  87         {
  88                 u32 ctr = 0;
  89                 u128 tctr = tmp[ctr];
  90                 u128 tctrp1 = tmp[ctr + 1];
  91                 u64 r0 = ((u64)(tctr)) & 0x7ffffffffffffLLU;
  92                 u128 c = ((tctr) >> (51));
  93                 tmp[ctr] = ((u128)(r0));
  94                 tmp[ctr + 1] = ((tctrp1) + (c));
  95         }
  96         {
  97                 u32 ctr = 1;
  98                 u128 tctr = tmp[ctr];
  99                 u128 tctrp1 = tmp[ctr + 1];
 100                 u64 r0 = ((u64)(tctr)) & 0x7ffffffffffffLLU;
 101                 u128 c = ((tctr) >> (51));
 102                 tmp[ctr] = ((u128)(r0));
 103                 tmp[ctr + 1] = ((tctrp1) + (c));
 104         }
 105
 106         {
 107                 u32 ctr = 2;
 108                 u128 tctr = tmp[ctr];
 109                 u128 tctrp1 = tmp[ctr + 1];
 110                 u64 r0 = ((u64)(tctr)) & 0x7ffffffffffffLLU;
 111                 u128 c = ((tctr) >> (51));
 112                 tmp[ctr] = ((u128)(r0));
 113                 tmp[ctr + 1] = ((tctrp1) + (c));
 114         }
 115         {
 116                 u32 ctr = 3;
 117                 u128 tctr = tmp[ctr];
 118                 u128 tctrp1 = tmp[ctr + 1];
 119                 u64 r0 = ((u64)(tctr)) & 0x7ffffffffffffLLU;
 120                 u128 c = ((tctr) >> (51));
 121                 tmp[ctr] = ((u128)(r0));
 122                 tmp[ctr + 1] = ((tctrp1) + (c));
 123         }
 124 }
 125
 126 static __always_inline void fmul_shift_reduce(u64 *output)
 127 {
 128         u64 tmp = output[4];
 129         u64 b0;
 130         {
 131                 u32 ctr = 5 - 0 - 1;
 132                 u64 z = output[ctr - 1];
 133                 output[ctr] = z;
 134         }
 135         {
 136                 u32 ctr = 5 - 1 - 1;
 137                 u64 z = output[ctr - 1];
 138                 output[ctr] = z;
 139         }
 140         {
 141                 u32 ctr = 5 - 2 - 1;
 142                 u64 z = output[ctr - 1];
 143                 output[ctr] = z;
 144         }
 145         {
 146                 u32 ctr = 5 - 3 - 1;
 147                 u64 z = output[ctr - 1];
 148                 output[ctr] = z;
 149         }
 150         output[0] = tmp;
 151         b0 = output[0];
 152         output[0] = 19 * b0;
 153 }
 154
 155 static __always_inline void fmul_mul_shift_reduce_(u128 *output, u64 *input,
 156                                                    u64 *input21)
 157 {
 158         u32 i;
 159         u64 input2i;
 160         {
 161                 u64 input2i = input21[0];
 162                 fproduct_sum_scalar_multiplication_(output, input, input2i);
 163                 fmul_shift_reduce(input);
 164         }
 165         {
 166                 u64 input2i = input21[1];
 167                 fproduct_sum_scalar_multiplication_(output, input, input2i);
 168                 fmul_shift_reduce(input);
 169         }
 170         {
 171                 u64 input2i = input21[2];
 172                 fproduct_sum_scalar_multiplication_(output, input, input2i);
 173                 fmul_shift_reduce(input);
 174         }
 175         {
 176                 u64 input2i = input21[3];
 177                 fproduct_sum_scalar_multiplication_(output, input, input2i);
 178                 fmul_shift_reduce(input);
 179         }
 180         i = 4;
 181         input2i = input21[i];
 182         fproduct_sum_scalar_multiplication_(output, input, input2i);
 183 }
 184
 185 static __always_inline void fmul_fmul(u64 *output, u64 *input, u64 *input21)
 186 {
 187         u64 tmp[5] = { input[0], input[1], input[2], input[3], input[4] };
 188         {
 189                 u128 b4;
 190                 u128 b0;
 191                 u128 b4_;
 192                 u128 b0_;
 193                 u64 i0;
 194                 u64 i1;
 195                 u64 i0_;
 196                 u64 i1_;
 197                 u128 t[5] = { 0 };
 198                 fmul_mul_shift_reduce_(t, tmp, input21);
 199                 fproduct_carry_wide_(t);
 200                 b4 = t[4];
 201                 b0 = t[0];
 202                 b4_ = ((b4) & (((u128)(0x7ffffffffffffLLU))));
 203                 b0_ = ((b0) + (((u128)(19) * (((u64)(((b4) >> (51))))))));
 204                 t[4] = b4_;
 205                 t[0] = b0_;
 206                 fproduct_copy_from_wide_(output, t);
 207                 i0 = output[0];
 208                 i1 = output[1];
 209                 i0_ = i0 & 0x7ffffffffffffLLU;
 210                 i1_ = i1 + (i0 >> 51);
 211                 output[0] = i0_;
 212                 output[1] = i1_;
 213         }
 214 }
 215
 216 static __always_inline void fsquare_fsquare__(u128 *tmp, u64 *output)
 217 {
 218         u64 r0 = output[0];
 219         u64 r1 = output[1];
 220         u64 r2 = output[2];
 221         u64 r3 = output[3];
 222         u64 r4 = output[4];
 223         u64 d0 = r0 * 2;
 224         u64 d1 = r1 * 2;
 225         u64 d2 = r2 * 2 * 19;
 226         u64 d419 = r4 * 19;
 227         u64 d4 = d419 * 2;
 228         u128 s0 = ((((((u128)(r0) * (r0))) + (((u128)(d4) * (r1))))) +
 229                    (((u128)(d2) * (r3))));
 230         u128 s1 = ((((((u128)(d0) * (r1))) + (((u128)(d4) * (r2))))) +
 231                    (((u128)(r3 * 19) * (r3))));
 232         u128 s2 = ((((((u128)(d0) * (r2))) + (((u128)(r1) * (r1))))) +
 233                    (((u128)(d4) * (r3))));
 234         u128 s3 = ((((((u128)(d0) * (r3))) + (((u128)(d1) * (r2))))) +
 235                    (((u128)(r4) * (d419))));
 236         u128 s4 = ((((((u128)(d0) * (r4))) + (((u128)(d1) * (r3))))) +
 237                    (((u128)(r2) * (r2))));
 238         tmp[0] = s0;
 239         tmp[1] = s1;
 240         tmp[2] = s2;
 241         tmp[3] = s3;
 242         tmp[4] = s4;
 243 }
 244
 245 static __always_inline void fsquare_fsquare_(u128 *tmp, u64 *output)
 246 {
 247         u128 b4;
 248         u128 b0;
 249         u128 b4_;
 250         u128 b0_;
 251         u64 i0;
 252         u64 i1;
 253         u64 i0_;
 254         u64 i1_;
 255         fsquare_fsquare__(tmp, output);
 256         fproduct_carry_wide_(tmp);
 257         b4 = tmp[4];
 258         b0 = tmp[0];
 259         b4_ = ((b4) & (((u128)(0x7ffffffffffffLLU))));
 260         b0_ = ((b0) + (((u128)(19) * (((u64)(((b4) >> (51))))))));
 261         tmp[4] = b4_;
 262         tmp[0] = b0_;
 263         fproduct_copy_from_wide_(output, tmp);
 264         i0 = output[0];
 265         i1 = output[1];
 266         i0_ = i0 & 0x7ffffffffffffLLU;
 267         i1_ = i1 + (i0 >> 51);
 268         output[0] = i0_;
 269         output[1] = i1_;
 270 }
 271
 272 static __always_inline void fsquare_fsquare_times_(u64 *output, u128 *tmp,
 273                                                    u32 count1)
 274 {
 275         u32 i;
 276         fsquare_fsquare_(tmp, output);
 277         for (i = 1; i < count1; ++i)
 278                 fsquare_fsquare_(tmp, output);
 279 }
 280
 281 static __always_inline void fsquare_fsquare_times(u64 *output, u64 *input,
 282                                                   u32 count1)
 283 {
 284         u128 t[5];
 285         memcpy(output, input, 5 * sizeof(*input));
 286         fsquare_fsquare_times_(output, t, count1);
 287 }
 288
 289 static __always_inline void fsquare_fsquare_times_inplace(u64 *output,
 290                                                           u32 count1)
 291 {
 292         u128 t[5];
 293         fsquare_fsquare_times_(output, t, count1);
 294 }
 295
 296 static __always_inline void crecip_crecip(u64 *out, u64 *z)
 297 {
 298         u64 buf[20] = { 0 };
 299         u64 *a0 = buf;
 300         u64 *t00 = buf + 5;
 301         u64 *b0 = buf + 10;
 302         u64 *t01;
 303         u64 *b1;
 304         u64 *c0;
 305         u64 *a;
 306         u64 *t0;
 307         u64 *b;
 308         u64 *c;
 309         fsquare_fsquare_times(a0, z, 1);
 310         fsquare_fsquare_times(t00, a0, 2);
 311         fmul_fmul(b0, t00, z);
 312         fmul_fmul(a0, b0, a0);
 313         fsquare_fsquare_times(t00, a0, 1);
 314         fmul_fmul(b0, t00, b0);
 315         fsquare_fsquare_times(t00, b0, 5);
 316         t01 = buf + 5;
 317         b1 = buf + 10;
 318         c0 = buf + 15;
 319         fmul_fmul(b1, t01, b1);
 320         fsquare_fsquare_times(t01, b1, 10);
 321         fmul_fmul(c0, t01, b1);
 322         fsquare_fsquare_times(t01, c0, 20);
 323         fmul_fmul(t01, t01, c0);
 324         fsquare_fsquare_times_inplace(t01, 10);
 325         fmul_fmul(b1, t01, b1);
 326         fsquare_fsquare_times(t01, b1, 50);
 327         a = buf;
 328         t0 = buf + 5;
 329         b = buf + 10;
 330         c = buf + 15;
 331         fmul_fmul(c, t0, b);
 332         fsquare_fsquare_times(t0, c, 100);
 333         fmul_fmul(t0, t0, c);
 334         fsquare_fsquare_times_inplace(t0, 50);
 335         fmul_fmul(t0, t0, b);
 336         fsquare_fsquare_times_inplace(t0, 5);
 337         fmul_fmul(out, t0, a);
 338 }
 339
 340 static __always_inline void fsum(u64 *a, u64 *b)
 341 {
 342         a[0] += b[0];
 343         a[1] += b[1];
 344         a[2] += b[2];
 345         a[3] += b[3];
 346         a[4] += b[4];
 347 }
 348
 349 static __always_inline void fdifference(u64 *a, u64 *b)
 350 {
 351         u64 tmp[5] = { 0 };
 352         u64 b0;
 353         u64 b1;
 354         u64 b2;
 355         u64 b3;
 356         u64 b4;
 357         memcpy(tmp, b, 5 * sizeof(*b));
 358         b0 = tmp[0];
 359         b1 = tmp[1];
 360         b2 = tmp[2];
 361         b3 = tmp[3];
 362         b4 = tmp[4];
 363         tmp[0] = b0 + 0x3fffffffffff68LLU;
 364         tmp[1] = b1 + 0x3ffffffffffff8LLU;
 365         tmp[2] = b2 + 0x3ffffffffffff8LLU;
 366         tmp[3] = b3 + 0x3ffffffffffff8LLU;
 367         tmp[4] = b4 + 0x3ffffffffffff8LLU;
 368         {
 369                 u64 xi = a[0];
 370                 u64 yi = tmp[0];
 371                 a[0] = yi - xi;
 372         }
 373         {
 374                 u64 xi = a[1];
 375                 u64 yi = tmp[1];
 376                 a[1] = yi - xi;
 377         }
 378         {
 379                 u64 xi = a[2];
 380                 u64 yi = tmp[2];
 381                 a[2] = yi - xi;
 382         }
 383         {
 384                 u64 xi = a[3];
 385                 u64 yi = tmp[3];
 386                 a[3] = yi - xi;
 387         }
 388         {
 389                 u64 xi = a[4];
 390                 u64 yi = tmp[4];
 391                 a[4] = yi - xi;
 392         }
 393 }
 394
 395 static __always_inline void fscalar(u64 *output, u64 *b, u64 s)
 396 {
 397         u128 tmp[5];
 398         u128 b4;
 399         u128 b0;
 400         u128 b4_;
 401         u128 b0_;
 402         {
 403                 u64 xi = b[0];
 404                 tmp[0] = ((u128)(xi) * (s));
 405         }
 406         {
 407                 u64 xi = b[1];
 408                 tmp[1] = ((u128)(xi) * (s));
 409         }
 410         {
 411                 u64 xi = b[2];
 412                 tmp[2] = ((u128)(xi) * (s));
 413         }
 414         {
 415                 u64 xi = b[3];
 416                 tmp[3] = ((u128)(xi) * (s));
 417         }
 418         {
 419                 u64 xi = b[4];
 420                 tmp[4] = ((u128)(xi) * (s));
 421         }
 422         fproduct_carry_wide_(tmp);
 423         b4 = tmp[4];
 424         b0 = tmp[0];
 425         b4_ = ((b4) & (((u128)(0x7ffffffffffffLLU))));
 426         b0_ = ((b0) + (((u128)(19) * (((u64)(((b4) >> (51))))))));
 427         tmp[4] = b4_;
 428         tmp[0] = b0_;
 429         fproduct_copy_from_wide_(output, tmp);
 430 }
 431
 432 static __always_inline void fmul(u64 *output, u64 *a, u64 *b)
 433 {
 434         fmul_fmul(output, a, b);
 435 }
 436
 437 static __always_inline void crecip(u64 *output, u64 *input)
 438 {
 439         crecip_crecip(output, input);
 440 }
 441
 442 static __always_inline void point_swap_conditional_step(u64 *a, u64 *b,
 443                                                         u64 swap1, u32 ctr)
 444 {
 445         u32 i = ctr - 1;
 446         u64 ai = a[i];
 447         u64 bi = b[i];
 448         u64 x = swap1 & (ai ^ bi);
 449         u64 ai1 = ai ^ x;
 450         u64 bi1 = bi ^ x;
 451         a[i] = ai1;
 452         b[i] = bi1;
 453 }
 454
 455 static __always_inline void point_swap_conditional5(u64 *a, u64 *b, u64 swap1)
 456 {
 457         point_swap_conditional_step(a, b, swap1, 5);
 458         point_swap_conditional_step(a, b, swap1, 4);
 459         point_swap_conditional_step(a, b, swap1, 3);
 460         point_swap_conditional_step(a, b, swap1, 2);
 461         point_swap_conditional_step(a, b, swap1, 1);
 462 }
 463
 464 static __always_inline void point_swap_conditional(u64 *a, u64 *b, u64 iswap)
 465 {
 466         u64 swap1 = 0 - iswap;
 467         point_swap_conditional5(a, b, swap1);
 468         point_swap_conditional5(a + 5, b + 5, swap1);
 469 }
 470
 471 static __always_inline void point_copy(u64 *output, u64 *input)
 472 {
 473         memcpy(output, input, 5 * sizeof(*input));
 474         memcpy(output + 5, input + 5, 5 * sizeof(*input));
 475 }
 476
 477 static __always_inline void addanddouble_fmonty(u64 *pp, u64 *ppq, u64 *p,
 478                                                 u64 *pq, u64 *qmqp)
 479 {
 480         u64 *qx = qmqp;
 481         u64 *x2 = pp;
 482         u64 *z2 = pp + 5;
 483         u64 *x3 = ppq;
 484         u64 *z3 = ppq + 5;
 485         u64 *x = p;
 486         u64 *z = p + 5;
 487         u64 *xprime = pq;
 488         u64 *zprime = pq + 5;
 489         u64 buf[40] = { 0 };
 490         u64 *origx = buf;
 491         u64 *origxprime0 = buf + 5;
 492         u64 *xxprime0;
 493         u64 *zzprime0;
 494         u64 *origxprime;
 495         xxprime0 = buf + 25;
 496         zzprime0 = buf + 30;
 497         memcpy(origx, x, 5 * sizeof(*x));
 498         fsum(x, z);
 499         fdifference(z, origx);
 500         memcpy(origxprime0, xprime, 5 * sizeof(*xprime));
 501         fsum(xprime, zprime);
 502         fdifference(zprime, origxprime0);
 503         fmul(xxprime0, xprime, z);
 504         fmul(zzprime0, x, zprime);
 505         origxprime = buf + 5;
 506         {
 507                 u64 *xx0;
 508                 u64 *zz0;
 509                 u64 *xxprime;
 510                 u64 *zzprime;
 511                 u64 *zzzprime;
 512                 xx0 = buf + 15;
 513                 zz0 = buf + 20;
 514                 xxprime = buf + 25;
 515                 zzprime = buf + 30;
 516                 zzzprime = buf + 35;
 517                 memcpy(origxprime, xxprime, 5 * sizeof(*xxprime));
 518                 fsum(xxprime, zzprime);
 519                 fdifference(zzprime, origxprime);
 520                 fsquare_fsquare_times(x3, xxprime, 1);
 521                 fsquare_fsquare_times(zzzprime, zzprime, 1);
 522                 fmul(z3, zzzprime, qx);
 523                 fsquare_fsquare_times(xx0, x, 1);
 524                 fsquare_fsquare_times(zz0, z, 1);
 525                 {
 526                         u64 *zzz;
 527                         u64 *xx;
 528                         u64 *zz;
 529                         u64 scalar;
 530                         zzz = buf + 10;
 531                         xx = buf + 15;
 532                         zz = buf + 20;
 533                         fmul(x2, xx, zz);
 534                         fdifference(zz, xx);
 535                         scalar = 121665;
 536                         fscalar(zzz, zz, scalar);
 537                         fsum(zzz, xx);
 538                         fmul(z2, zzz, zz);
 539                 }
 540         }
 541 }
 542
 543 static __always_inline void
 544 ladder_smallloop_cmult_small_loop_step(u64 *nq, u64 *nqpq, u64 *nq2, u64 *nqpq2,
 545                                        u64 *q, u8 byt)
 546 {
 547         u64 bit0 = (u64)(byt >> 7);
 548         u64 bit;
 549         point_swap_conditional(nq, nqpq, bit0);
 550         addanddouble_fmonty(nq2, nqpq2, nq, nqpq, q);
 551         bit = (u64)(byt >> 7);
 552         point_swap_conditional(nq2, nqpq2, bit);
 553 }
 554
 555 static __always_inline void
 556 ladder_smallloop_cmult_small_loop_double_step(u64 *nq, u64 *nqpq, u64 *nq2,
 557                                               u64 *nqpq2, u64 *q, u8 byt)
 558 {
 559         u8 byt1;
 560         ladder_smallloop_cmult_small_loop_step(nq, nqpq, nq2, nqpq2, q, byt);
 561         byt1 = byt << 1;
 562         ladder_smallloop_cmult_small_loop_step(nq2, nqpq2, nq, nqpq, q, byt1);
 563 }
 564
 565 static __always_inline void
 566 ladder_smallloop_cmult_small_loop(u64 *nq, u64 *nqpq, u64 *nq2, u64 *nqpq2,
 567                                   u64 *q, u8 byt, u32 i)
 568 {
 569         while (i--) {
 570                 ladder_smallloop_cmult_small_loop_double_step(nq, nqpq, nq2,
 571                                                               nqpq2, q, byt);
 572                 byt <<= 2;
 573         }
 574 }
 575
 576 static __always_inline void ladder_bigloop_cmult_big_loop(u8 *n1, u64 *nq,
 577                                                           u64 *nqpq, u64 *nq2,
 578                                                           u64 *nqpq2, u64 *q,
 579                                                           u32 i)
 580 {
 581         while (i--) {
 582                 u8 byte = n1[i];
 583                 ladder_smallloop_cmult_small_loop(nq, nqpq, nq2, nqpq2, q,
 584                                                   byte, 4);
 585         }
 586 }
 587
 588 static void ladder_cmult(u64 *result, u8 *n1, u64 *q)
 589 {
 590         u64 point_buf[40] = { 0 };
 591         u64 *nq = point_buf;
 592         u64 *nqpq = point_buf + 10;
 593         u64 *nq2 = point_buf + 20;
 594         u64 *nqpq2 = point_buf + 30;
 595         point_copy(nqpq, q);
 596         nq[0] = 1;
 597         ladder_bigloop_cmult_big_loop(n1, nq, nqpq, nq2, nqpq2, q, 32);
 598         point_copy(result, nq);
 599 }
 600
 601 static __always_inline void format_fexpand(u64 *output, const u8 *input)
 602 {
 603         const u8 *x00 = input + 6;
 604         const u8 *x01 = input + 12;
 605         const u8 *x02 = input + 19;
 606         const u8 *x0 = input + 24;
 607         u64 i0, i1, i2, i3, i4, output0, output1, output2, output3, output4;
 608         i0 = get_unaligned_le64(input);
 609         i1 = get_unaligned_le64(x00);
 610         i2 = get_unaligned_le64(x01);
 611         i3 = get_unaligned_le64(x02);
 612         i4 = get_unaligned_le64(x0);
 613         output0 = i0 & 0x7ffffffffffffLLU;
 614         output1 = i1 >> 3 & 0x7ffffffffffffLLU;
 615         output2 = i2 >> 6 & 0x7ffffffffffffLLU;
 616         output3 = i3 >> 1 & 0x7ffffffffffffLLU;
 617         output4 = i4 >> 12 & 0x7ffffffffffffLLU;
 618         output[0] = output0;
 619         output[1] = output1;
 620         output[2] = output2;
 621         output[3] = output3;
 622         output[4] = output4;
 623 }
 624
 625 static __always_inline void format_fcontract_first_carry_pass(u64 *input)
 626 {
 627         u64 t0 = input[0];
 628         u64 t1 = input[1];
 629         u64 t2 = input[2];
 630         u64 t3 = input[3];
 631         u64 t4 = input[4];
 632         u64 t1_ = t1 + (t0 >> 51);
 633         u64 t0_ = t0 & 0x7ffffffffffffLLU;
 634         u64 t2_ = t2 + (t1_ >> 51);
 635         u64 t1__ = t1_ & 0x7ffffffffffffLLU;
 636         u64 t3_ = t3 + (t2_ >> 51);
 637         u64 t2__ = t2_ & 0x7ffffffffffffLLU;
 638         u64 t4_ = t4 + (t3_ >> 51);
 639         u64 t3__ = t3_ & 0x7ffffffffffffLLU;
 640         input[0] = t0_;
 641         input[1] = t1__;
 642         input[2] = t2__;
 643         input[3] = t3__;
 644         input[4] = t4_;
 645 }
 646
 647 static __always_inline void format_fcontract_first_carry_full(u64 *input)
 648 {
 649         format_fcontract_first_carry_pass(input);
 650         modulo_carry_top(input);
 651 }
 652
 653 static __always_inline void format_fcontract_second_carry_pass(u64 *input)
 654 {
 655         u64 t0 = input[0];
 656         u64 t1 = input[1];
 657         u64 t2 = input[2];
 658         u64 t3 = input[3];
 659         u64 t4 = input[4];
 660         u64 t1_ = t1 + (t0 >> 51);
 661         u64 t0_ = t0 & 0x7ffffffffffffLLU;
 662         u64 t2_ = t2 + (t1_ >> 51);
 663         u64 t1__ = t1_ & 0x7ffffffffffffLLU;
 664         u64 t3_ = t3 + (t2_ >> 51);
 665         u64 t2__ = t2_ & 0x7ffffffffffffLLU;
 666         u64 t4_ = t4 + (t3_ >> 51);
 667         u64 t3__ = t3_ & 0x7ffffffffffffLLU;
 668         input[0] = t0_;
 669         input[1] = t1__;
 670         input[2] = t2__;
 671         input[3] = t3__;
 672         input[4] = t4_;
 673 }
 674
 675 static __always_inline void format_fcontract_second_carry_full(u64 *input)
 676 {
 677         u64 i0;
 678         u64 i1;
 679         u64 i0_;
 680         u64 i1_;
 681         format_fcontract_second_carry_pass(input);
 682         modulo_carry_top(input);
 683         i0 = input[0];
 684         i1 = input[1];
 685         i0_ = i0 & 0x7ffffffffffffLLU;
 686         i1_ = i1 + (i0 >> 51);
 687         input[0] = i0_;
 688         input[1] = i1_;
 689 }
 690
 691 static __always_inline void format_fcontract_trim(u64 *input)
 692 {
 693         u64 a0 = input[0];
 694         u64 a1 = input[1];
 695         u64 a2 = input[2];
 696         u64 a3 = input[3];
 697         u64 a4 = input[4];
 698         u64 mask0 = u64_gte_mask(a0, 0x7ffffffffffedLLU);
 699         u64 mask1 = u64_eq_mask(a1, 0x7ffffffffffffLLU);
 700         u64 mask2 = u64_eq_mask(a2, 0x7ffffffffffffLLU);
 701         u64 mask3 = u64_eq_mask(a3, 0x7ffffffffffffLLU);
 702         u64 mask4 = u64_eq_mask(a4, 0x7ffffffffffffLLU);
 703         u64 mask = (((mask0 & mask1) & mask2) & mask3) & mask4;
 704         u64 a0_ = a0 - (0x7ffffffffffedLLU & mask);
 705         u64 a1_ = a1 - (0x7ffffffffffffLLU & mask);
 706         u64 a2_ = a2 - (0x7ffffffffffffLLU & mask);
 707         u64 a3_ = a3 - (0x7ffffffffffffLLU & mask);
 708         u64 a4_ = a4 - (0x7ffffffffffffLLU & mask);
 709         input[0] = a0_;
 710         input[1] = a1_;
 711         input[2] = a2_;
 712         input[3] = a3_;
 713         input[4] = a4_;
 714 }
 715
 716 static __always_inline void format_fcontract_store(u8 *output, u64 *input)
 717 {
 718         u64 t0 = input[0];
 719         u64 t1 = input[1];
 720         u64 t2 = input[2];
 721         u64 t3 = input[3];
 722         u64 t4 = input[4];
 723         u64 o0 = t1 << 51 | t0;
 724         u64 o1 = t2 << 38 | t1 >> 13;
 725         u64 o2 = t3 << 25 | t2 >> 26;
 726         u64 o3 = t4 << 12 | t3 >> 39;
 727         u8 *b0 = output;
 728         u8 *b1 = output + 8;
 729         u8 *b2 = output + 16;
 730         u8 *b3 = output + 24;
 731         put_unaligned_le64(o0, b0);
 732         put_unaligned_le64(o1, b1);
 733         put_unaligned_le64(o2, b2);
 734         put_unaligned_le64(o3, b3);
 735 }
 736
 737 static __always_inline void format_fcontract(u8 *output, u64 *input)
 738 {
 739         format_fcontract_first_carry_full(input);
 740         format_fcontract_second_carry_full(input);
 741         format_fcontract_trim(input);
 742         format_fcontract_store(output, input);
 743 }
 744
 745 static __always_inline void format_scalar_of_point(u8 *scalar, u64 *point)
 746 {
 747         u64 *x = point;
 748         u64 *z = point + 5;
 749         u64 buf[10] __aligned(32) = { 0 };
 750         u64 *zmone = buf;
 751         u64 *sc = buf + 5;
 752         crecip(zmone, z);
 753         fmul(sc, x, zmone);
 754         format_fcontract(scalar, sc);
 755 }
 756
 757 void curve25519_generic(u8 mypublic[CURVE25519_KEY_SIZE],
 758                         const u8 secret[CURVE25519_KEY_SIZE],
 759                         const u8 basepoint[CURVE25519_KEY_SIZE])
 760 {
 761         u64 buf0[10] __aligned(32) = { 0 };
 762         u64 *x0 = buf0;
 763         u64 *z = buf0 + 5;
 764         u64 *q;
 765         format_fexpand(x0, basepoint);
 766         z[0] = 1;
 767         q = buf0;
 768         {
 769                 u8 e[32] __aligned(32) = { 0 };
 770                 u8 *scalar;
 771                 memcpy(e, secret, 32);
 772                 curve25519_clamp_secret(e);
 773                 scalar = e;
 774                 {
 775                         u64 buf[15] = { 0 };
 776                         u64 *nq = buf;
 777                         u64 *x = nq;
 778                         x[0] = 1;
 779                         ladder_cmult(nq, scalar, q);
 780                         format_scalar_of_point(mypublic, nq);
 781                         memzero_explicit(buf, sizeof(buf));
 782                 }
 783                 memzero_explicit(e, sizeof(e));
 784         }
 785         memzero_explicit(buf0, sizeof(buf0));
 786 }