bignum_mod.h

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/*
 *  Copyright The Mbed TLS Contributors
 *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
 */
 
#ifndef MBEDTLS_BIGNUM_MOD_H
#define MBEDTLS_BIGNUM_MOD_H
 
#include "common.h"
 
#if defined(MBEDTLS_BIGNUM_C)
#include "mbedtls/bignum.h"
#endif
 
typedef enum {
    MBEDTLS_MPI_MOD_REP_INVALID    = 0,
    /* Skip 1 as it is slightly easier to accidentally pass to functions. */
    MBEDTLS_MPI_MOD_REP_MONTGOMERY = 2,
    /* Optimised reduction available. This indicates a coordinate modulus (P)
     * and one or more of the following have been configured:
     * - A nist curve (MBEDTLS_ECP_DP_SECPXXXR1_ENABLED) & MBEDTLS_ECP_NIST_OPTIM.
     * - A Kobliz Curve.
     * - A Fast Reduction Curve CURVE25519 or CURVE448. */
    MBEDTLS_MPI_MOD_REP_OPT_RED,
} mbedtls_mpi_mod_rep_selector;
 
/* Make mbedtls_mpi_mod_rep_selector and mbedtls_mpi_mod_ext_rep disjoint to
 * make it easier to catch when they are accidentally swapped. */
typedef enum {
    MBEDTLS_MPI_MOD_EXT_REP_INVALID = 0,
    MBEDTLS_MPI_MOD_EXT_REP_LE      = 8,
    MBEDTLS_MPI_MOD_EXT_REP_BE
} mbedtls_mpi_mod_ext_rep;
 
typedef struct {
    mbedtls_mpi_uint *p;
    size_t limbs;
} mbedtls_mpi_mod_residue;
 
typedef struct {
    mbedtls_mpi_uint const *rr;  /* The residue for 2^{2*n*biL} mod N */
    mbedtls_mpi_uint mm;         /* Montgomery const for -N^{-1} mod 2^{ciL} */
} mbedtls_mpi_mont_struct;
 
typedef int (*mbedtls_mpi_modp_fn)(mbedtls_mpi_uint *X, size_t X_limbs);
 
typedef struct {
    mbedtls_mpi_modp_fn modp;    /* The optimised reduction function pointer */
} mbedtls_mpi_opt_red_struct;
 
typedef struct {
    const mbedtls_mpi_uint *p;
    size_t limbs;                            // number of limbs
    size_t bits;                             // bitlen of p
    mbedtls_mpi_mod_rep_selector int_rep;    // selector to signal the active member of the union
    union rep {
        /* if int_rep == #MBEDTLS_MPI_MOD_REP_MONTGOMERY */
        mbedtls_mpi_mont_struct mont;
        /* if int_rep == #MBEDTLS_MPI_MOD_REP_OPT_RED */
        mbedtls_mpi_opt_red_struct ored;
    } rep;
} mbedtls_mpi_mod_modulus;
 
int mbedtls_mpi_mod_residue_setup(mbedtls_mpi_mod_residue *r,
                                  const mbedtls_mpi_mod_modulus *N,
                                  mbedtls_mpi_uint *p,
                                  size_t p_limbs);
 
void mbedtls_mpi_mod_residue_release(mbedtls_mpi_mod_residue *r);
 
void mbedtls_mpi_mod_modulus_init(mbedtls_mpi_mod_modulus *N);
 
int mbedtls_mpi_mod_modulus_setup(mbedtls_mpi_mod_modulus *N,
                                  const mbedtls_mpi_uint *p,
                                  size_t p_limbs);
 
int mbedtls_mpi_mod_optred_modulus_setup(mbedtls_mpi_mod_modulus *N,
                                         const mbedtls_mpi_uint *p,
                                         size_t p_limbs,
                                         mbedtls_mpi_modp_fn modp);
 
void mbedtls_mpi_mod_modulus_free(mbedtls_mpi_mod_modulus *N);
 
int mbedtls_mpi_mod_mul(mbedtls_mpi_mod_residue *X,
                        const mbedtls_mpi_mod_residue *A,
                        const mbedtls_mpi_mod_residue *B,
                        const mbedtls_mpi_mod_modulus *N);
 
int mbedtls_mpi_mod_sub(mbedtls_mpi_mod_residue *X,
                        const mbedtls_mpi_mod_residue *A,
                        const mbedtls_mpi_mod_residue *B,
                        const mbedtls_mpi_mod_modulus *N);
 
int mbedtls_mpi_mod_inv(mbedtls_mpi_mod_residue *X,
                        const mbedtls_mpi_mod_residue *A,
                        const mbedtls_mpi_mod_modulus *N);
int mbedtls_mpi_mod_add(mbedtls_mpi_mod_residue *X,
                        const mbedtls_mpi_mod_residue *A,
                        const mbedtls_mpi_mod_residue *B,
                        const mbedtls_mpi_mod_modulus *N);
 
int mbedtls_mpi_mod_random(mbedtls_mpi_mod_residue *X,
                           mbedtls_mpi_uint min,
                           const mbedtls_mpi_mod_modulus *N,
                           int (*f_rng)(void *, unsigned char *, size_t),
                           void *p_rng);
 
int mbedtls_mpi_mod_read(mbedtls_mpi_mod_residue *r,
                         const mbedtls_mpi_mod_modulus *N,
                         const unsigned char *buf,
                         size_t buflen,
                         mbedtls_mpi_mod_ext_rep ext_rep);
 
int mbedtls_mpi_mod_write(const mbedtls_mpi_mod_residue *r,
                          const mbedtls_mpi_mod_modulus *N,
                          unsigned char *buf,
                          size_t buflen,
                          mbedtls_mpi_mod_ext_rep ext_rep);
 
#endif /* MBEDTLS_BIGNUM_MOD_H */