Bitcoin ABC  0.24.7
P2P Digital Currency
modinv64.h
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1 /***********************************************************************
2  * Copyright (c) 2020 Peter Dettman *
3  * Distributed under the MIT software license, see the accompanying *
4  * file COPYING or https://www.opensource.org/licenses/mit-license.php.*
5  **********************************************************************/
6 
7 #ifndef SECP256K1_MODINV64_H
8 #define SECP256K1_MODINV64_H
9 
10 #if defined HAVE_CONFIG_H
11 #include "libsecp256k1-config.h"
12 #endif
13 
14 #include "util.h"
15 
16 #ifndef SECP256K1_WIDEMUL_INT128
17 #error "modinv64 requires 128-bit wide multiplication support"
18 #endif
19 
20 /* A signed 62-bit limb representation of integers.
21  *
22  * Its value is sum(v[i] * 2^(62*i), i=0..4). */
23 typedef struct {
24  int64_t v[5];
26 
27 typedef struct {
28  /* The modulus in signed62 notation, must be odd and in [3, 2^256]. */
30 
31  /* modulus^{-1} mod 2^62 */
32  uint64_t modulus_inv62;
34 
35 /* Replace x with its modular inverse mod modinfo->modulus. x must be in range [0, modulus).
36  * If x is zero, the result will be zero as well. If not, the inverse must exist (i.e., the gcd of
37  * x and modulus must be 1). These rules are automatically satisfied if the modulus is prime.
38  *
39  * On output, all of x's limbs will be in [0, 2^62).
40  */
42 
43 /* Same as secp256k1_modinv64_var, but constant time in x (not in the modulus). */
45 
46 #endif /* SECP256K1_MODINV64_H */
util.h
secp256k1_modinv64_var
static void secp256k1_modinv64_var(secp256k1_modinv64_signed62 *x, const secp256k1_modinv64_modinfo *modinfo)
secp256k1_modinv64_modinfo::modulus_inv62
uint64_t modulus_inv62
Definition: modinv64.h:32
secp256k1_modinv64_modinfo
Definition: modinv64.h:27
secp256k1_modinv64_modinfo::modulus
secp256k1_modinv64_signed62 modulus
Definition: modinv64.h:29
secp256k1_modinv64_signed62
Definition: modinv64.h:23
secp256k1_modinv64
static void secp256k1_modinv64(secp256k1_modinv64_signed62 *x, const secp256k1_modinv64_modinfo *modinfo)