Line | Count | Source |
1 | | /* |
2 | | * Copyright Supranational LLC |
3 | | * Licensed under the Apache License, Version 2.0, see LICENSE for details. |
4 | | * SPDX-License-Identifier: Apache-2.0 |
5 | | */ |
6 | | |
7 | | #include "vect.h" |
8 | | |
9 | | /* |
10 | | * |out| = |inp|^|pow|, small footprint, public exponent |
11 | | */ |
12 | | static void exp_mont_384(vec384 out, const vec384 inp, const byte *pow, |
13 | | size_t pow_bits, const vec384 p, limb_t n0) |
14 | 0 | { |
15 | 0 | #if 1 |
16 | 0 | vec384 ret; |
17 | 0 |
|
18 | 0 | vec_copy(ret, inp, sizeof(ret)); /* ret = inp^1 */ |
19 | 0 | --pow_bits; /* most significant bit is set, skip over */ |
20 | 0 | while (pow_bits--) { |
21 | 0 | sqr_mont_384(ret, ret, p, n0); |
22 | 0 | if (is_bit_set(pow, pow_bits)) |
23 | 0 | mul_mont_384(ret, ret, inp, p, n0); |
24 | 0 | } |
25 | 0 | vec_copy(out, ret, sizeof(ret)); /* out = ret */ |
26 | 0 | #else |
27 | 0 | unsigned int i; |
28 | 0 | vec384 sqr; |
29 | 0 |
|
30 | 0 | vec_copy(sqr, inp, sizeof(sqr)); |
31 | 0 | for (i = 0; !is_bit_set(pow, i++);) |
32 | 0 | sqr_mont_384(sqr, sqr, sqr, p, n0); |
33 | 0 | vec_copy(out, sqr, sizeof(sqr)); |
34 | 0 | for (; i < pow_bits; i++) { |
35 | 0 | sqr_mont_384(sqr, sqr, sqr, p, n0); |
36 | 0 | if (is_bit_set(pow, i)) |
37 | 0 | mul_mont_384(out, out, sqr, p, n0); |
38 | 0 | } |
39 | 0 | #endif |
40 | 0 | } |
41 | | |
42 | | static void exp_mont_384x(vec384x out, const vec384x inp, const byte *pow, |
43 | | size_t pow_bits, const vec384 p, limb_t n0) |
44 | 0 | { |
45 | 0 | vec384x ret; |
46 | 0 |
|
47 | 0 | vec_copy(ret, inp, sizeof(ret)); /* |ret| = |inp|^1 */ |
48 | 0 | --pow_bits; /* most significant bit is accounted for, skip over */ |
49 | 0 | while (pow_bits--) { |
50 | 0 | sqr_mont_384x(ret, ret, p, n0); |
51 | 0 | if (is_bit_set(pow, pow_bits)) |
52 | 0 | mul_mont_384x(ret, ret, inp, p, n0); |
53 | 0 | } |
54 | 0 | vec_copy(out, ret, sizeof(ret)); /* |out| = |ret| */ |
55 | 0 | } |