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 }
787
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