rust-secp256k1-unsafe-fast/secp256k1-sys/depend/secp256k1/src/scalar.h

118 lines
6.2 KiB
C

/***********************************************************************
* Copyright (c) 2014 Pieter Wuille *
* Distributed under the MIT software license, see the accompanying *
* file COPYING or https://www.opensource.org/licenses/mit-license.php.*
***********************************************************************/
#ifndef SECP256K1_SCALAR_H
#define SECP256K1_SCALAR_H
#include "num.h"
#include "util.h"
#if defined HAVE_CONFIG_H
#include "libsecp256k1-config.h"
#endif
#if defined(EXHAUSTIVE_TEST_ORDER)
#include "scalar_low.h"
#elif defined(SECP256K1_WIDEMUL_INT128)
#include "scalar_4x64.h"
#elif defined(SECP256K1_WIDEMUL_INT64)
#include "scalar_8x32.h"
#else
#error "Please select wide multiplication implementation"
#endif
/** Clear a scalar to prevent the leak of sensitive data. */
static void rustsecp256k1_v0_4_0_scalar_clear(rustsecp256k1_v0_4_0_scalar *r);
/** Access bits from a scalar. All requested bits must belong to the same 32-bit limb. */
static unsigned int rustsecp256k1_v0_4_0_scalar_get_bits(const rustsecp256k1_v0_4_0_scalar *a, unsigned int offset, unsigned int count);
/** Access bits from a scalar. Not constant time. */
static unsigned int rustsecp256k1_v0_4_0_scalar_get_bits_var(const rustsecp256k1_v0_4_0_scalar *a, unsigned int offset, unsigned int count);
/** Set a scalar from a big endian byte array. The scalar will be reduced modulo group order `n`.
* In: bin: pointer to a 32-byte array.
* Out: r: scalar to be set.
* overflow: non-zero if the scalar was bigger or equal to `n` before reduction, zero otherwise (can be NULL).
*/
static void rustsecp256k1_v0_4_0_scalar_set_b32(rustsecp256k1_v0_4_0_scalar *r, const unsigned char *bin, int *overflow);
/** Set a scalar from a big endian byte array and returns 1 if it is a valid
* seckey and 0 otherwise. */
static int rustsecp256k1_v0_4_0_scalar_set_b32_seckey(rustsecp256k1_v0_4_0_scalar *r, const unsigned char *bin);
/** Set a scalar to an unsigned integer. */
static void rustsecp256k1_v0_4_0_scalar_set_int(rustsecp256k1_v0_4_0_scalar *r, unsigned int v);
/** Convert a scalar to a byte array. */
static void rustsecp256k1_v0_4_0_scalar_get_b32(unsigned char *bin, const rustsecp256k1_v0_4_0_scalar* a);
/** Add two scalars together (modulo the group order). Returns whether it overflowed. */
static int rustsecp256k1_v0_4_0_scalar_add(rustsecp256k1_v0_4_0_scalar *r, const rustsecp256k1_v0_4_0_scalar *a, const rustsecp256k1_v0_4_0_scalar *b);
/** Conditionally add a power of two to a scalar. The result is not allowed to overflow. */
static void rustsecp256k1_v0_4_0_scalar_cadd_bit(rustsecp256k1_v0_4_0_scalar *r, unsigned int bit, int flag);
/** Multiply two scalars (modulo the group order). */
static void rustsecp256k1_v0_4_0_scalar_mul(rustsecp256k1_v0_4_0_scalar *r, const rustsecp256k1_v0_4_0_scalar *a, const rustsecp256k1_v0_4_0_scalar *b);
/** Shift a scalar right by some amount strictly between 0 and 16, returning
* the low bits that were shifted off */
static int rustsecp256k1_v0_4_0_scalar_shr_int(rustsecp256k1_v0_4_0_scalar *r, int n);
/** Compute the square of a scalar (modulo the group order). */
static void rustsecp256k1_v0_4_0_scalar_sqr(rustsecp256k1_v0_4_0_scalar *r, const rustsecp256k1_v0_4_0_scalar *a);
/** Compute the inverse of a scalar (modulo the group order). */
static void rustsecp256k1_v0_4_0_scalar_inverse(rustsecp256k1_v0_4_0_scalar *r, const rustsecp256k1_v0_4_0_scalar *a);
/** Compute the inverse of a scalar (modulo the group order), without constant-time guarantee. */
static void rustsecp256k1_v0_4_0_scalar_inverse_var(rustsecp256k1_v0_4_0_scalar *r, const rustsecp256k1_v0_4_0_scalar *a);
/** Compute the complement of a scalar (modulo the group order). */
static void rustsecp256k1_v0_4_0_scalar_negate(rustsecp256k1_v0_4_0_scalar *r, const rustsecp256k1_v0_4_0_scalar *a);
/** Check whether a scalar equals zero. */
static int rustsecp256k1_v0_4_0_scalar_is_zero(const rustsecp256k1_v0_4_0_scalar *a);
/** Check whether a scalar equals one. */
static int rustsecp256k1_v0_4_0_scalar_is_one(const rustsecp256k1_v0_4_0_scalar *a);
/** Check whether a scalar, considered as an nonnegative integer, is even. */
static int rustsecp256k1_v0_4_0_scalar_is_even(const rustsecp256k1_v0_4_0_scalar *a);
/** Check whether a scalar is higher than the group order divided by 2. */
static int rustsecp256k1_v0_4_0_scalar_is_high(const rustsecp256k1_v0_4_0_scalar *a);
/** Conditionally negate a number, in constant time.
* Returns -1 if the number was negated, 1 otherwise */
static int rustsecp256k1_v0_4_0_scalar_cond_negate(rustsecp256k1_v0_4_0_scalar *a, int flag);
#ifndef USE_NUM_NONE
/** Convert a scalar to a number. */
static void rustsecp256k1_v0_4_0_scalar_get_num(rustsecp256k1_v0_4_0_num *r, const rustsecp256k1_v0_4_0_scalar *a);
/** Get the order of the group as a number. */
static void rustsecp256k1_v0_4_0_scalar_order_get_num(rustsecp256k1_v0_4_0_num *r);
#endif
/** Compare two scalars. */
static int rustsecp256k1_v0_4_0_scalar_eq(const rustsecp256k1_v0_4_0_scalar *a, const rustsecp256k1_v0_4_0_scalar *b);
/** Find r1 and r2 such that r1+r2*2^128 = k. */
static void rustsecp256k1_v0_4_0_scalar_split_128(rustsecp256k1_v0_4_0_scalar *r1, rustsecp256k1_v0_4_0_scalar *r2, const rustsecp256k1_v0_4_0_scalar *k);
/** Find r1 and r2 such that r1+r2*lambda = k,
* where r1 and r2 or their negations are maximum 128 bits long (see rustsecp256k1_v0_4_0_ge_mul_lambda). */
static void rustsecp256k1_v0_4_0_scalar_split_lambda(rustsecp256k1_v0_4_0_scalar *r1, rustsecp256k1_v0_4_0_scalar *r2, const rustsecp256k1_v0_4_0_scalar *k);
/** Multiply a and b (without taking the modulus!), divide by 2**shift, and round to the nearest integer. Shift must be at least 256. */
static void rustsecp256k1_v0_4_0_scalar_mul_shift_var(rustsecp256k1_v0_4_0_scalar *r, const rustsecp256k1_v0_4_0_scalar *a, const rustsecp256k1_v0_4_0_scalar *b, unsigned int shift);
/** If flag is true, set *r equal to *a; otherwise leave it. Constant-time. Both *r and *a must be initialized.*/
static void rustsecp256k1_v0_4_0_scalar_cmov(rustsecp256k1_v0_4_0_scalar *r, const rustsecp256k1_v0_4_0_scalar *a, int flag);
#endif /* SECP256K1_SCALAR_H */