git / moonbite-core / src/secp256k1-zkp/src/field.h · raw

/********************************************************************** * Copyright (c) 2013, 2014 Pieter Wuille                             * * Distributed under the MIT software license, see the accompanying   * * file COPYING or http://www.opensource.org/licenses/mit-license.php.* **********************************************************************/#ifndef SECP256K1_FIELD_H#define SECP256K1_FIELD_H/** Field element module. * *  Field elements can be represented in several ways, but code accessing *  it (and implementations) need to take certain properties into account: *  - Each field element can be normalized or not. *  - Each field element has a magnitude, which represents how far away *    its representation is away from normalization. Normalized elements *    always have a magnitude of 1, but a magnitude of 1 doesn't imply *    normality. */#if defined HAVE_CONFIG_H#include "libsecp256k1-config.h"#endif#if defined(USE_FIELD_10X26)#include "field_10x26.h"#elif defined(USE_FIELD_5X52)#include "field_5x52.h"#else#error "Please select field implementation"#endif#include "util.h"/** Normalize a field element. */static void secp256k1_fe_normalize(secp256k1_fe *r);/** Weakly normalize a field element: reduce it magnitude to 1, but don't fully normalize. */static void secp256k1_fe_normalize_weak(secp256k1_fe *r);/** Normalize a field element, without constant-time guarantee. */static void secp256k1_fe_normalize_var(secp256k1_fe *r);/** Verify whether a field element represents zero i.e. would normalize to a zero value. The field *  implementation may optionally normalize the input, but this should not be relied upon. */static int secp256k1_fe_normalizes_to_zero(secp256k1_fe *r);/** Verify whether a field element represents zero i.e. would normalize to a zero value. The field *  implementation may optionally normalize the input, but this should not be relied upon. */static int secp256k1_fe_normalizes_to_zero_var(secp256k1_fe *r);/** Set a field element equal to a small integer. Resulting field element is normalized. */static void secp256k1_fe_set_int(secp256k1_fe *r, int a);/** Sets a field element equal to zero, initializing all fields. */static void secp256k1_fe_clear(secp256k1_fe *a);/** Verify whether a field element is zero. Requires the input to be normalized. */static int secp256k1_fe_is_zero(const secp256k1_fe *a);/** Check the "oddness" of a field element. Requires the input to be normalized. */static int secp256k1_fe_is_odd(const secp256k1_fe *a);/** Compare two field elements. Requires magnitude-1 inputs. */static int secp256k1_fe_equal(const secp256k1_fe *a, const secp256k1_fe *b);/** Same as secp256k1_fe_equal, but may be variable time. */static int secp256k1_fe_equal_var(const secp256k1_fe *a, const secp256k1_fe *b);/** Compare two field elements. Requires both inputs to be normalized */static int secp256k1_fe_cmp_var(const secp256k1_fe *a, const secp256k1_fe *b);/** Set a field element equal to 32-byte big endian value. If successful, the resulting field element is normalized. */static int secp256k1_fe_set_b32(secp256k1_fe *r, const unsigned char *a);/** Convert a field element to a 32-byte big endian value. Requires the input to be normalized */static void secp256k1_fe_get_b32(unsigned char *r, const secp256k1_fe *a);/** Set a field element equal to the additive inverse of another. Takes a maximum magnitude of the input *  as an argument. The magnitude of the output is one higher. */static void secp256k1_fe_negate(secp256k1_fe *r, const secp256k1_fe *a, int m);/** Multiplies the passed field element with a small integer constant. Multiplies the magnitude by that *  small integer. */static void secp256k1_fe_mul_int(secp256k1_fe *r, int a);/** Adds a field element to another. The result has the sum of the inputs' magnitudes as magnitude. */static void secp256k1_fe_add(secp256k1_fe *r, const secp256k1_fe *a);/** Sets a field element to be the product of two others. Requires the inputs' magnitudes to be at most 8. *  The output magnitude is 1 (but not guaranteed to be normalized). */static void secp256k1_fe_mul(secp256k1_fe *r, const secp256k1_fe *a, const secp256k1_fe * SECP256K1_RESTRICT b);/** Sets a field element to be the square of another. Requires the input's magnitude to be at most 8. *  The output magnitude is 1 (but not guaranteed to be normalized). */static void secp256k1_fe_sqr(secp256k1_fe *r, const secp256k1_fe *a);/** If a has a square root, it is computed in r and 1 is returned. If a does not *  have a square root, the root of its negation is computed and 0 is returned. *  The input's magnitude can be at most 8. The output magnitude is 1 (but not *  guaranteed to be normalized). The result in r will always be a square *  itself. */static int secp256k1_fe_sqrt(secp256k1_fe *r, const secp256k1_fe *a);/** Checks whether a field element is a quadratic residue. */static int secp256k1_fe_is_quad_var(const secp256k1_fe *a);/** Sets a field element to be the (modular) inverse of another. Requires the input's magnitude to be *  at most 8. The output magnitude is 1 (but not guaranteed to be normalized). */static void secp256k1_fe_inv(secp256k1_fe *r, const secp256k1_fe *a);/** Potentially faster version of secp256k1_fe_inv, without constant-time guarantee. */static void secp256k1_fe_inv_var(secp256k1_fe *r, const secp256k1_fe *a);/** Calculate the (modular) inverses of a batch of field elements. Requires the inputs' magnitudes to be *  at most 8. The output magnitudes are 1 (but not guaranteed to be normalized). The inputs and *  outputs must not overlap in memory. */static void secp256k1_fe_inv_all_var(secp256k1_fe *r, const secp256k1_fe *a, size_t len);/** Convert a field element to the storage type. */static void secp256k1_fe_to_storage(secp256k1_fe_storage *r, const secp256k1_fe *a);/** Convert a field element back from the storage type. */static void secp256k1_fe_from_storage(secp256k1_fe *r, const secp256k1_fe_storage *a);/** If flag is true, set *r equal to *a; otherwise leave it. Constant-time. */static void secp256k1_fe_storage_cmov(secp256k1_fe_storage *r, const secp256k1_fe_storage *a, int flag);/** If flag is true, set *r equal to *a; otherwise leave it. Constant-time. */static void secp256k1_fe_cmov(secp256k1_fe *r, const secp256k1_fe *a, int flag);#endif /* SECP256K1_FIELD_H */