Loading...
Note: File does not exist in v3.5.6.
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
17typedef __uint128_t u128;
18
19static __always_inline u64 u64_eq_mask(u64 a, u64 b)
20{
21 u64 x = a ^ b;
22 u64 minus_x = ~x + (u64)1U;
23 u64 x_or_minus_x = x | minus_x;
24 u64 xnx = x_or_minus_x >> (u32)63U;
25 u64 c = xnx - (u64)1U;
26 return c;
27}
28
29static __always_inline u64 u64_gte_mask(u64 a, u64 b)
30{
31 u64 x = a;
32 u64 y = b;
33 u64 x_xor_y = x ^ y;
34 u64 x_sub_y = x - y;
35 u64 x_sub_y_xor_y = x_sub_y ^ y;
36 u64 q = x_xor_y | x_sub_y_xor_y;
37 u64 x_xor_q = x ^ q;
38 u64 x_xor_q_ = x_xor_q >> (u32)63U;
39 u64 c = x_xor_q_ - (u64)1U;
40 return c;
41}
42
43static __always_inline void modulo_carry_top(u64 *b)
44{
45 u64 b4 = b[4];
46 u64 b0 = b[0];
47 u64 b4_ = b4 & 0x7ffffffffffffLLU;
48 u64 b0_ = b0 + 19 * (b4 >> 51);
49 b[4] = b4_;
50 b[0] = b0_;
51}
52
53static __always_inline void fproduct_copy_from_wide_(u64 *output, u128 *input)
54{
55 {
56 u128 xi = input[0];
57 output[0] = ((u64)(xi));
58 }
59 {
60 u128 xi = input[1];
61 output[1] = ((u64)(xi));
62 }
63 {
64 u128 xi = input[2];
65 output[2] = ((u64)(xi));
66 }
67 {
68 u128 xi = input[3];
69 output[3] = ((u64)(xi));
70 }
71 {
72 u128 xi = input[4];
73 output[4] = ((u64)(xi));
74 }
75}
76
77static __always_inline void
78fproduct_sum_scalar_multiplication_(u128 *output, u64 *input, u64 s)
79{
80 output[0] += (u128)input[0] * s;
81 output[1] += (u128)input[1] * s;
82 output[2] += (u128)input[2] * s;
83 output[3] += (u128)input[3] * s;
84 output[4] += (u128)input[4] * s;
85}
86
87static __always_inline void fproduct_carry_wide_(u128 *tmp)
88{
89 {
90 u32 ctr = 0;
91 u128 tctr = tmp[ctr];
92 u128 tctrp1 = tmp[ctr + 1];
93 u64 r0 = ((u64)(tctr)) & 0x7ffffffffffffLLU;
94 u128 c = ((tctr) >> (51));
95 tmp[ctr] = ((u128)(r0));
96 tmp[ctr + 1] = ((tctrp1) + (c));
97 }
98 {
99 u32 ctr = 1;
100 u128 tctr = tmp[ctr];
101 u128 tctrp1 = tmp[ctr + 1];
102 u64 r0 = ((u64)(tctr)) & 0x7ffffffffffffLLU;
103 u128 c = ((tctr) >> (51));
104 tmp[ctr] = ((u128)(r0));
105 tmp[ctr + 1] = ((tctrp1) + (c));
106 }
107
108 {
109 u32 ctr = 2;
110 u128 tctr = tmp[ctr];
111 u128 tctrp1 = tmp[ctr + 1];
112 u64 r0 = ((u64)(tctr)) & 0x7ffffffffffffLLU;
113 u128 c = ((tctr) >> (51));
114 tmp[ctr] = ((u128)(r0));
115 tmp[ctr + 1] = ((tctrp1) + (c));
116 }
117 {
118 u32 ctr = 3;
119 u128 tctr = tmp[ctr];
120 u128 tctrp1 = tmp[ctr + 1];
121 u64 r0 = ((u64)(tctr)) & 0x7ffffffffffffLLU;
122 u128 c = ((tctr) >> (51));
123 tmp[ctr] = ((u128)(r0));
124 tmp[ctr + 1] = ((tctrp1) + (c));
125 }
126}
127
128static __always_inline void fmul_shift_reduce(u64 *output)
129{
130 u64 tmp = output[4];
131 u64 b0;
132 {
133 u32 ctr = 5 - 0 - 1;
134 u64 z = output[ctr - 1];
135 output[ctr] = z;
136 }
137 {
138 u32 ctr = 5 - 1 - 1;
139 u64 z = output[ctr - 1];
140 output[ctr] = z;
141 }
142 {
143 u32 ctr = 5 - 2 - 1;
144 u64 z = output[ctr - 1];
145 output[ctr] = z;
146 }
147 {
148 u32 ctr = 5 - 3 - 1;
149 u64 z = output[ctr - 1];
150 output[ctr] = z;
151 }
152 output[0] = tmp;
153 b0 = output[0];
154 output[0] = 19 * b0;
155}
156
157static __always_inline void fmul_mul_shift_reduce_(u128 *output, u64 *input,
158 u64 *input21)
159{
160 u32 i;
161 u64 input2i;
162 {
163 u64 input2i = input21[0];
164 fproduct_sum_scalar_multiplication_(output, input, input2i);
165 fmul_shift_reduce(input);
166 }
167 {
168 u64 input2i = input21[1];
169 fproduct_sum_scalar_multiplication_(output, input, input2i);
170 fmul_shift_reduce(input);
171 }
172 {
173 u64 input2i = input21[2];
174 fproduct_sum_scalar_multiplication_(output, input, input2i);
175 fmul_shift_reduce(input);
176 }
177 {
178 u64 input2i = input21[3];
179 fproduct_sum_scalar_multiplication_(output, input, input2i);
180 fmul_shift_reduce(input);
181 }
182 i = 4;
183 input2i = input21[i];
184 fproduct_sum_scalar_multiplication_(output, input, input2i);
185}
186
187static __always_inline void fmul_fmul(u64 *output, u64 *input, u64 *input21)
188{
189 u64 tmp[5] = { input[0], input[1], input[2], input[3], input[4] };
190 {
191 u128 b4;
192 u128 b0;
193 u128 b4_;
194 u128 b0_;
195 u64 i0;
196 u64 i1;
197 u64 i0_;
198 u64 i1_;
199 u128 t[5] = { 0 };
200 fmul_mul_shift_reduce_(t, tmp, input21);
201 fproduct_carry_wide_(t);
202 b4 = t[4];
203 b0 = t[0];
204 b4_ = ((b4) & (((u128)(0x7ffffffffffffLLU))));
205 b0_ = ((b0) + (((u128)(19) * (((u64)(((b4) >> (51))))))));
206 t[4] = b4_;
207 t[0] = b0_;
208 fproduct_copy_from_wide_(output, t);
209 i0 = output[0];
210 i1 = output[1];
211 i0_ = i0 & 0x7ffffffffffffLLU;
212 i1_ = i1 + (i0 >> 51);
213 output[0] = i0_;
214 output[1] = i1_;
215 }
216}
217
218static __always_inline void fsquare_fsquare__(u128 *tmp, u64 *output)
219{
220 u64 r0 = output[0];
221 u64 r1 = output[1];
222 u64 r2 = output[2];
223 u64 r3 = output[3];
224 u64 r4 = output[4];
225 u64 d0 = r0 * 2;
226 u64 d1 = r1 * 2;
227 u64 d2 = r2 * 2 * 19;
228 u64 d419 = r4 * 19;
229 u64 d4 = d419 * 2;
230 u128 s0 = ((((((u128)(r0) * (r0))) + (((u128)(d4) * (r1))))) +
231 (((u128)(d2) * (r3))));
232 u128 s1 = ((((((u128)(d0) * (r1))) + (((u128)(d4) * (r2))))) +
233 (((u128)(r3 * 19) * (r3))));
234 u128 s2 = ((((((u128)(d0) * (r2))) + (((u128)(r1) * (r1))))) +
235 (((u128)(d4) * (r3))));
236 u128 s3 = ((((((u128)(d0) * (r3))) + (((u128)(d1) * (r2))))) +
237 (((u128)(r4) * (d419))));
238 u128 s4 = ((((((u128)(d0) * (r4))) + (((u128)(d1) * (r3))))) +
239 (((u128)(r2) * (r2))));
240 tmp[0] = s0;
241 tmp[1] = s1;
242 tmp[2] = s2;
243 tmp[3] = s3;
244 tmp[4] = s4;
245}
246
247static __always_inline void fsquare_fsquare_(u128 *tmp, u64 *output)
248{
249 u128 b4;
250 u128 b0;
251 u128 b4_;
252 u128 b0_;
253 u64 i0;
254 u64 i1;
255 u64 i0_;
256 u64 i1_;
257 fsquare_fsquare__(tmp, output);
258 fproduct_carry_wide_(tmp);
259 b4 = tmp[4];
260 b0 = tmp[0];
261 b4_ = ((b4) & (((u128)(0x7ffffffffffffLLU))));
262 b0_ = ((b0) + (((u128)(19) * (((u64)(((b4) >> (51))))))));
263 tmp[4] = b4_;
264 tmp[0] = b0_;
265 fproduct_copy_from_wide_(output, tmp);
266 i0 = output[0];
267 i1 = output[1];
268 i0_ = i0 & 0x7ffffffffffffLLU;
269 i1_ = i1 + (i0 >> 51);
270 output[0] = i0_;
271 output[1] = i1_;
272}
273
274static __always_inline void fsquare_fsquare_times_(u64 *output, u128 *tmp,
275 u32 count1)
276{
277 u32 i;
278 fsquare_fsquare_(tmp, output);
279 for (i = 1; i < count1; ++i)
280 fsquare_fsquare_(tmp, output);
281}
282
283static __always_inline void fsquare_fsquare_times(u64 *output, u64 *input,
284 u32 count1)
285{
286 u128 t[5];
287 memcpy(output, input, 5 * sizeof(*input));
288 fsquare_fsquare_times_(output, t, count1);
289}
290
291static __always_inline void fsquare_fsquare_times_inplace(u64 *output,
292 u32 count1)
293{
294 u128 t[5];
295 fsquare_fsquare_times_(output, t, count1);
296}
297
298static __always_inline void crecip_crecip(u64 *out, u64 *z)
299{
300 u64 buf[20] = { 0 };
301 u64 *a0 = buf;
302 u64 *t00 = buf + 5;
303 u64 *b0 = buf + 10;
304 u64 *t01;
305 u64 *b1;
306 u64 *c0;
307 u64 *a;
308 u64 *t0;
309 u64 *b;
310 u64 *c;
311 fsquare_fsquare_times(a0, z, 1);
312 fsquare_fsquare_times(t00, a0, 2);
313 fmul_fmul(b0, t00, z);
314 fmul_fmul(a0, b0, a0);
315 fsquare_fsquare_times(t00, a0, 1);
316 fmul_fmul(b0, t00, b0);
317 fsquare_fsquare_times(t00, b0, 5);
318 t01 = buf + 5;
319 b1 = buf + 10;
320 c0 = buf + 15;
321 fmul_fmul(b1, t01, b1);
322 fsquare_fsquare_times(t01, b1, 10);
323 fmul_fmul(c0, t01, b1);
324 fsquare_fsquare_times(t01, c0, 20);
325 fmul_fmul(t01, t01, c0);
326 fsquare_fsquare_times_inplace(t01, 10);
327 fmul_fmul(b1, t01, b1);
328 fsquare_fsquare_times(t01, b1, 50);
329 a = buf;
330 t0 = buf + 5;
331 b = buf + 10;
332 c = buf + 15;
333 fmul_fmul(c, t0, b);
334 fsquare_fsquare_times(t0, c, 100);
335 fmul_fmul(t0, t0, c);
336 fsquare_fsquare_times_inplace(t0, 50);
337 fmul_fmul(t0, t0, b);
338 fsquare_fsquare_times_inplace(t0, 5);
339 fmul_fmul(out, t0, a);
340}
341
342static __always_inline void fsum(u64 *a, u64 *b)
343{
344 a[0] += b[0];
345 a[1] += b[1];
346 a[2] += b[2];
347 a[3] += b[3];
348 a[4] += b[4];
349}
350
351static __always_inline void fdifference(u64 *a, u64 *b)
352{
353 u64 tmp[5] = { 0 };
354 u64 b0;
355 u64 b1;
356 u64 b2;
357 u64 b3;
358 u64 b4;
359 memcpy(tmp, b, 5 * sizeof(*b));
360 b0 = tmp[0];
361 b1 = tmp[1];
362 b2 = tmp[2];
363 b3 = tmp[3];
364 b4 = tmp[4];
365 tmp[0] = b0 + 0x3fffffffffff68LLU;
366 tmp[1] = b1 + 0x3ffffffffffff8LLU;
367 tmp[2] = b2 + 0x3ffffffffffff8LLU;
368 tmp[3] = b3 + 0x3ffffffffffff8LLU;
369 tmp[4] = b4 + 0x3ffffffffffff8LLU;
370 {
371 u64 xi = a[0];
372 u64 yi = tmp[0];
373 a[0] = yi - xi;
374 }
375 {
376 u64 xi = a[1];
377 u64 yi = tmp[1];
378 a[1] = yi - xi;
379 }
380 {
381 u64 xi = a[2];
382 u64 yi = tmp[2];
383 a[2] = yi - xi;
384 }
385 {
386 u64 xi = a[3];
387 u64 yi = tmp[3];
388 a[3] = yi - xi;
389 }
390 {
391 u64 xi = a[4];
392 u64 yi = tmp[4];
393 a[4] = yi - xi;
394 }
395}
396
397static __always_inline void fscalar(u64 *output, u64 *b, u64 s)
398{
399 u128 tmp[5];
400 u128 b4;
401 u128 b0;
402 u128 b4_;
403 u128 b0_;
404 {
405 u64 xi = b[0];
406 tmp[0] = ((u128)(xi) * (s));
407 }
408 {
409 u64 xi = b[1];
410 tmp[1] = ((u128)(xi) * (s));
411 }
412 {
413 u64 xi = b[2];
414 tmp[2] = ((u128)(xi) * (s));
415 }
416 {
417 u64 xi = b[3];
418 tmp[3] = ((u128)(xi) * (s));
419 }
420 {
421 u64 xi = b[4];
422 tmp[4] = ((u128)(xi) * (s));
423 }
424 fproduct_carry_wide_(tmp);
425 b4 = tmp[4];
426 b0 = tmp[0];
427 b4_ = ((b4) & (((u128)(0x7ffffffffffffLLU))));
428 b0_ = ((b0) + (((u128)(19) * (((u64)(((b4) >> (51))))))));
429 tmp[4] = b4_;
430 tmp[0] = b0_;
431 fproduct_copy_from_wide_(output, tmp);
432}
433
434static __always_inline void fmul(u64 *output, u64 *a, u64 *b)
435{
436 fmul_fmul(output, a, b);
437}
438
439static __always_inline void crecip(u64 *output, u64 *input)
440{
441 crecip_crecip(output, input);
442}
443
444static __always_inline void point_swap_conditional_step(u64 *a, u64 *b,
445 u64 swap1, u32 ctr)
446{
447 u32 i = ctr - 1;
448 u64 ai = a[i];
449 u64 bi = b[i];
450 u64 x = swap1 & (ai ^ bi);
451 u64 ai1 = ai ^ x;
452 u64 bi1 = bi ^ x;
453 a[i] = ai1;
454 b[i] = bi1;
455}
456
457static __always_inline void point_swap_conditional5(u64 *a, u64 *b, u64 swap1)
458{
459 point_swap_conditional_step(a, b, swap1, 5);
460 point_swap_conditional_step(a, b, swap1, 4);
461 point_swap_conditional_step(a, b, swap1, 3);
462 point_swap_conditional_step(a, b, swap1, 2);
463 point_swap_conditional_step(a, b, swap1, 1);
464}
465
466static __always_inline void point_swap_conditional(u64 *a, u64 *b, u64 iswap)
467{
468 u64 swap1 = 0 - iswap;
469 point_swap_conditional5(a, b, swap1);
470 point_swap_conditional5(a + 5, b + 5, swap1);
471}
472
473static __always_inline void point_copy(u64 *output, u64 *input)
474{
475 memcpy(output, input, 5 * sizeof(*input));
476 memcpy(output + 5, input + 5, 5 * sizeof(*input));
477}
478
479static __always_inline void addanddouble_fmonty(u64 *pp, u64 *ppq, u64 *p,
480 u64 *pq, u64 *qmqp)
481{
482 u64 *qx = qmqp;
483 u64 *x2 = pp;
484 u64 *z2 = pp + 5;
485 u64 *x3 = ppq;
486 u64 *z3 = ppq + 5;
487 u64 *x = p;
488 u64 *z = p + 5;
489 u64 *xprime = pq;
490 u64 *zprime = pq + 5;
491 u64 buf[40] = { 0 };
492 u64 *origx = buf;
493 u64 *origxprime0 = buf + 5;
494 u64 *xxprime0;
495 u64 *zzprime0;
496 u64 *origxprime;
497 xxprime0 = buf + 25;
498 zzprime0 = buf + 30;
499 memcpy(origx, x, 5 * sizeof(*x));
500 fsum(x, z);
501 fdifference(z, origx);
502 memcpy(origxprime0, xprime, 5 * sizeof(*xprime));
503 fsum(xprime, zprime);
504 fdifference(zprime, origxprime0);
505 fmul(xxprime0, xprime, z);
506 fmul(zzprime0, x, zprime);
507 origxprime = buf + 5;
508 {
509 u64 *xx0;
510 u64 *zz0;
511 u64 *xxprime;
512 u64 *zzprime;
513 u64 *zzzprime;
514 xx0 = buf + 15;
515 zz0 = buf + 20;
516 xxprime = buf + 25;
517 zzprime = buf + 30;
518 zzzprime = buf + 35;
519 memcpy(origxprime, xxprime, 5 * sizeof(*xxprime));
520 fsum(xxprime, zzprime);
521 fdifference(zzprime, origxprime);
522 fsquare_fsquare_times(x3, xxprime, 1);
523 fsquare_fsquare_times(zzzprime, zzprime, 1);
524 fmul(z3, zzzprime, qx);
525 fsquare_fsquare_times(xx0, x, 1);
526 fsquare_fsquare_times(zz0, z, 1);
527 {
528 u64 *zzz;
529 u64 *xx;
530 u64 *zz;
531 u64 scalar;
532 zzz = buf + 10;
533 xx = buf + 15;
534 zz = buf + 20;
535 fmul(x2, xx, zz);
536 fdifference(zz, xx);
537 scalar = 121665;
538 fscalar(zzz, zz, scalar);
539 fsum(zzz, xx);
540 fmul(z2, zzz, zz);
541 }
542 }
543}
544
545static __always_inline void
546ladder_smallloop_cmult_small_loop_step(u64 *nq, u64 *nqpq, u64 *nq2, u64 *nqpq2,
547 u64 *q, u8 byt)
548{
549 u64 bit0 = (u64)(byt >> 7);
550 u64 bit;
551 point_swap_conditional(nq, nqpq, bit0);
552 addanddouble_fmonty(nq2, nqpq2, nq, nqpq, q);
553 bit = (u64)(byt >> 7);
554 point_swap_conditional(nq2, nqpq2, bit);
555}
556
557static __always_inline void
558ladder_smallloop_cmult_small_loop_double_step(u64 *nq, u64 *nqpq, u64 *nq2,
559 u64 *nqpq2, u64 *q, u8 byt)
560{
561 u8 byt1;
562 ladder_smallloop_cmult_small_loop_step(nq, nqpq, nq2, nqpq2, q, byt);
563 byt1 = byt << 1;
564 ladder_smallloop_cmult_small_loop_step(nq2, nqpq2, nq, nqpq, q, byt1);
565}
566
567static __always_inline void
568ladder_smallloop_cmult_small_loop(u64 *nq, u64 *nqpq, u64 *nq2, u64 *nqpq2,
569 u64 *q, u8 byt, u32 i)
570{
571 while (i--) {
572 ladder_smallloop_cmult_small_loop_double_step(nq, nqpq, nq2,
573 nqpq2, q, byt);
574 byt <<= 2;
575 }
576}
577
578static __always_inline void ladder_bigloop_cmult_big_loop(u8 *n1, u64 *nq,
579 u64 *nqpq, u64 *nq2,
580 u64 *nqpq2, u64 *q,
581 u32 i)
582{
583 while (i--) {
584 u8 byte = n1[i];
585 ladder_smallloop_cmult_small_loop(nq, nqpq, nq2, nqpq2, q,
586 byte, 4);
587 }
588}
589
590static void ladder_cmult(u64 *result, u8 *n1, u64 *q)
591{
592 u64 point_buf[40] = { 0 };
593 u64 *nq = point_buf;
594 u64 *nqpq = point_buf + 10;
595 u64 *nq2 = point_buf + 20;
596 u64 *nqpq2 = point_buf + 30;
597 point_copy(nqpq, q);
598 nq[0] = 1;
599 ladder_bigloop_cmult_big_loop(n1, nq, nqpq, nq2, nqpq2, q, 32);
600 point_copy(result, nq);
601}
602
603static __always_inline void format_fexpand(u64 *output, const u8 *input)
604{
605 const u8 *x00 = input + 6;
606 const u8 *x01 = input + 12;
607 const u8 *x02 = input + 19;
608 const u8 *x0 = input + 24;
609 u64 i0, i1, i2, i3, i4, output0, output1, output2, output3, output4;
610 i0 = get_unaligned_le64(input);
611 i1 = get_unaligned_le64(x00);
612 i2 = get_unaligned_le64(x01);
613 i3 = get_unaligned_le64(x02);
614 i4 = get_unaligned_le64(x0);
615 output0 = i0 & 0x7ffffffffffffLLU;
616 output1 = i1 >> 3 & 0x7ffffffffffffLLU;
617 output2 = i2 >> 6 & 0x7ffffffffffffLLU;
618 output3 = i3 >> 1 & 0x7ffffffffffffLLU;
619 output4 = i4 >> 12 & 0x7ffffffffffffLLU;
620 output[0] = output0;
621 output[1] = output1;
622 output[2] = output2;
623 output[3] = output3;
624 output[4] = output4;
625}
626
627static __always_inline void format_fcontract_first_carry_pass(u64 *input)
628{
629 u64 t0 = input[0];
630 u64 t1 = input[1];
631 u64 t2 = input[2];
632 u64 t3 = input[3];
633 u64 t4 = input[4];
634 u64 t1_ = t1 + (t0 >> 51);
635 u64 t0_ = t0 & 0x7ffffffffffffLLU;
636 u64 t2_ = t2 + (t1_ >> 51);
637 u64 t1__ = t1_ & 0x7ffffffffffffLLU;
638 u64 t3_ = t3 + (t2_ >> 51);
639 u64 t2__ = t2_ & 0x7ffffffffffffLLU;
640 u64 t4_ = t4 + (t3_ >> 51);
641 u64 t3__ = t3_ & 0x7ffffffffffffLLU;
642 input[0] = t0_;
643 input[1] = t1__;
644 input[2] = t2__;
645 input[3] = t3__;
646 input[4] = t4_;
647}
648
649static __always_inline void format_fcontract_first_carry_full(u64 *input)
650{
651 format_fcontract_first_carry_pass(input);
652 modulo_carry_top(input);
653}
654
655static __always_inline void format_fcontract_second_carry_pass(u64 *input)
656{
657 u64 t0 = input[0];
658 u64 t1 = input[1];
659 u64 t2 = input[2];
660 u64 t3 = input[3];
661 u64 t4 = input[4];
662 u64 t1_ = t1 + (t0 >> 51);
663 u64 t0_ = t0 & 0x7ffffffffffffLLU;
664 u64 t2_ = t2 + (t1_ >> 51);
665 u64 t1__ = t1_ & 0x7ffffffffffffLLU;
666 u64 t3_ = t3 + (t2_ >> 51);
667 u64 t2__ = t2_ & 0x7ffffffffffffLLU;
668 u64 t4_ = t4 + (t3_ >> 51);
669 u64 t3__ = t3_ & 0x7ffffffffffffLLU;
670 input[0] = t0_;
671 input[1] = t1__;
672 input[2] = t2__;
673 input[3] = t3__;
674 input[4] = t4_;
675}
676
677static __always_inline void format_fcontract_second_carry_full(u64 *input)
678{
679 u64 i0;
680 u64 i1;
681 u64 i0_;
682 u64 i1_;
683 format_fcontract_second_carry_pass(input);
684 modulo_carry_top(input);
685 i0 = input[0];
686 i1 = input[1];
687 i0_ = i0 & 0x7ffffffffffffLLU;
688 i1_ = i1 + (i0 >> 51);
689 input[0] = i0_;
690 input[1] = i1_;
691}
692
693static __always_inline void format_fcontract_trim(u64 *input)
694{
695 u64 a0 = input[0];
696 u64 a1 = input[1];
697 u64 a2 = input[2];
698 u64 a3 = input[3];
699 u64 a4 = input[4];
700 u64 mask0 = u64_gte_mask(a0, 0x7ffffffffffedLLU);
701 u64 mask1 = u64_eq_mask(a1, 0x7ffffffffffffLLU);
702 u64 mask2 = u64_eq_mask(a2, 0x7ffffffffffffLLU);
703 u64 mask3 = u64_eq_mask(a3, 0x7ffffffffffffLLU);
704 u64 mask4 = u64_eq_mask(a4, 0x7ffffffffffffLLU);
705 u64 mask = (((mask0 & mask1) & mask2) & mask3) & mask4;
706 u64 a0_ = a0 - (0x7ffffffffffedLLU & mask);
707 u64 a1_ = a1 - (0x7ffffffffffffLLU & mask);
708 u64 a2_ = a2 - (0x7ffffffffffffLLU & mask);
709 u64 a3_ = a3 - (0x7ffffffffffffLLU & mask);
710 u64 a4_ = a4 - (0x7ffffffffffffLLU & mask);
711 input[0] = a0_;
712 input[1] = a1_;
713 input[2] = a2_;
714 input[3] = a3_;
715 input[4] = a4_;
716}
717
718static __always_inline void format_fcontract_store(u8 *output, u64 *input)
719{
720 u64 t0 = input[0];
721 u64 t1 = input[1];
722 u64 t2 = input[2];
723 u64 t3 = input[3];
724 u64 t4 = input[4];
725 u64 o0 = t1 << 51 | t0;
726 u64 o1 = t2 << 38 | t1 >> 13;
727 u64 o2 = t3 << 25 | t2 >> 26;
728 u64 o3 = t4 << 12 | t3 >> 39;
729 u8 *b0 = output;
730 u8 *b1 = output + 8;
731 u8 *b2 = output + 16;
732 u8 *b3 = output + 24;
733 put_unaligned_le64(o0, b0);
734 put_unaligned_le64(o1, b1);
735 put_unaligned_le64(o2, b2);
736 put_unaligned_le64(o3, b3);
737}
738
739static __always_inline void format_fcontract(u8 *output, u64 *input)
740{
741 format_fcontract_first_carry_full(input);
742 format_fcontract_second_carry_full(input);
743 format_fcontract_trim(input);
744 format_fcontract_store(output, input);
745}
746
747static __always_inline void format_scalar_of_point(u8 *scalar, u64 *point)
748{
749 u64 *x = point;
750 u64 *z = point + 5;
751 u64 buf[10] __aligned(32) = { 0 };
752 u64 *zmone = buf;
753 u64 *sc = buf + 5;
754 crecip(zmone, z);
755 fmul(sc, x, zmone);
756 format_fcontract(scalar, sc);
757}
758
759void curve25519_generic(u8 mypublic[CURVE25519_KEY_SIZE],
760 const u8 secret[CURVE25519_KEY_SIZE],
761 const u8 basepoint[CURVE25519_KEY_SIZE])
762{
763 u64 buf0[10] __aligned(32) = { 0 };
764 u64 *x0 = buf0;
765 u64 *z = buf0 + 5;
766 u64 *q;
767 format_fexpand(x0, basepoint);
768 z[0] = 1;
769 q = buf0;
770 {
771 u8 e[32] __aligned(32) = { 0 };
772 u8 *scalar;
773 memcpy(e, secret, 32);
774 curve25519_clamp_secret(e);
775 scalar = e;
776 {
777 u64 buf[15] = { 0 };
778 u64 *nq = buf;
779 u64 *x = nq;
780 x[0] = 1;
781 ladder_cmult(nq, scalar, q);
782 format_scalar_of_point(mypublic, nq);
783 memzero_explicit(buf, sizeof(buf));
784 }
785 memzero_explicit(e, sizeof(e));
786 }
787 memzero_explicit(buf0, sizeof(buf0));
788}