/src/botan/build/include/botan/internal/monty_exp.h
Line | Count | Source |
1 | | /* |
2 | | * (C) 2018 Jack Lloyd |
3 | | * |
4 | | * Botan is released under the Simplified BSD License (see license.txt) |
5 | | */ |
6 | | |
7 | | #ifndef BOTAN_MONTY_EXP_H_ |
8 | | #define BOTAN_MONTY_EXP_H_ |
9 | | |
10 | | #include <memory> |
11 | | #include <botan/bigint.h> |
12 | | |
13 | | namespace Botan { |
14 | | |
15 | | class Modular_Reducer; |
16 | | |
17 | | class Montgomery_Params; |
18 | | |
19 | | class Montgomery_Exponentation_State; |
20 | | |
21 | | /* |
22 | | * Precompute for calculating values g^x mod p |
23 | | */ |
24 | | std::shared_ptr<const Montgomery_Exponentation_State> |
25 | | monty_precompute(const std::shared_ptr<const Montgomery_Params>& params_p, |
26 | | const BigInt& g, |
27 | | size_t window_bits, |
28 | | bool const_time = true); |
29 | | |
30 | | /* |
31 | | * Return g^k mod p |
32 | | */ |
33 | | BigInt monty_execute(const Montgomery_Exponentation_State& precomputed_state, |
34 | | const BigInt& k, size_t max_k_bits); |
35 | | |
36 | | /* |
37 | | * Return g^k mod p taking variable time depending on k |
38 | | * @warning only use this if k is public |
39 | | */ |
40 | | BigInt monty_execute_vartime(const Montgomery_Exponentation_State& precomputed_state, |
41 | | const BigInt& k); |
42 | | |
43 | | inline |
44 | | BigInt monty_exp(std::shared_ptr<const Montgomery_Params> params_p, |
45 | | const BigInt& g, const BigInt& k, size_t max_k_bits) |
46 | 779 | { |
47 | 779 | auto precomputed = monty_precompute(params_p, g, 4, true); |
48 | 779 | return monty_execute(*precomputed, k, max_k_bits); |
49 | 779 | } |
50 | | |
51 | | inline |
52 | | BigInt monty_exp_vartime(std::shared_ptr<const Montgomery_Params> params_p, |
53 | | const BigInt& g, const BigInt& k) |
54 | 105k | { |
55 | 105k | auto precomputed = monty_precompute(params_p, g, 4, false); |
56 | 105k | return monty_execute_vartime(*precomputed, k); |
57 | 105k | } |
58 | | |
59 | | /** |
60 | | * Return (x^z1 * y^z2) % p |
61 | | */ |
62 | | BigInt monty_multi_exp(const std::shared_ptr<const Montgomery_Params>& params_p, |
63 | | const BigInt& x, |
64 | | const BigInt& z1, |
65 | | const BigInt& y, |
66 | | const BigInt& z2); |
67 | | |
68 | | } |
69 | | |
70 | | #endif |