1 /** 2 * \file bignum_internal.h 3 * 4 * \brief Internal-only bignum public-key cryptosystem API. 5 * 6 * This file declares bignum-related functions that are to be used 7 * only from within the Mbed TLS library itself. 8 * 9 */ 10 /* 11 * Copyright The Mbed TLS Contributors 12 * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later 13 */ 14 #ifndef MBEDTLS_BIGNUM_INTERNAL_H 15 #define MBEDTLS_BIGNUM_INTERNAL_H 16 17 /** 18 * \brief Perform a modular exponentiation: X = A^E mod N 19 * 20 * \warning This function is not constant time with respect to \p E (the exponent). 21 * 22 * \param X The destination MPI. This must point to an initialized MPI. 23 * This must not alias E or N. 24 * \param A The base of the exponentiation. 25 * This must point to an initialized MPI. 26 * \param E The exponent MPI. This must point to an initialized MPI. 27 * \param N The base for the modular reduction. This must point to an 28 * initialized MPI. 29 * \param prec_RR A helper MPI depending solely on \p N which can be used to 30 * speed-up multiple modular exponentiations for the same value 31 * of \p N. This may be \c NULL. If it is not \c NULL, it must 32 * point to an initialized MPI. If it hasn't been used after 33 * the call to mbedtls_mpi_init(), this function will compute 34 * the helper value and store it in \p prec_RR for reuse on 35 * subsequent calls to this function. Otherwise, the function 36 * will assume that \p prec_RR holds the helper value set by a 37 * previous call to mbedtls_mpi_exp_mod(), and reuse it. 38 * 39 * \return \c 0 if successful. 40 * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if a memory allocation failed. 41 * \return #MBEDTLS_ERR_MPI_BAD_INPUT_DATA if \c N is negative or 42 * even, or if \c E is negative. 43 * \return Another negative error code on different kinds of failures. 44 * 45 */ 46 int mbedtls_mpi_exp_mod_unsafe(mbedtls_mpi *X, const mbedtls_mpi *A, 47 const mbedtls_mpi *E, const mbedtls_mpi *N, 48 mbedtls_mpi *prec_RR); 49 50 #endif /* bignum_internal.h */ 51
