51 lines
2.2 KiB
C++
51 lines
2.2 KiB
C++
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/**
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* \file bignum_internal.h
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*
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* \brief Internal-only bignum public-key cryptosystem API.
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*
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* This file declares bignum-related functions that are to be used
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* only from within the Mbed TLS library itself.
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*
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*/
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/*
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* Copyright The Mbed TLS Contributors
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* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
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*/
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#ifndef MBEDTLS_BIGNUM_INTERNAL_H
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#define MBEDTLS_BIGNUM_INTERNAL_H
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/**
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* \brief Perform a modular exponentiation: X = A^E mod N
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*
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* \warning This function is not constant time with respect to \p E (the exponent).
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*
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* \param X The destination MPI. This must point to an initialized MPI.
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* This must not alias E or N.
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* \param A The base of the exponentiation.
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* This must point to an initialized MPI.
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* \param E The exponent MPI. This must point to an initialized MPI.
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* \param N The base for the modular reduction. This must point to an
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* initialized MPI.
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* \param prec_RR A helper MPI depending solely on \p N which can be used to
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* speed-up multiple modular exponentiations for the same value
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* of \p N. This may be \c NULL. If it is not \c NULL, it must
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* point to an initialized MPI. If it hasn't been used after
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* the call to mbedtls_mpi_init(), this function will compute
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* the helper value and store it in \p prec_RR for reuse on
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* subsequent calls to this function. Otherwise, the function
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* will assume that \p prec_RR holds the helper value set by a
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* previous call to mbedtls_mpi_exp_mod(), and reuse it.
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*
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* \return \c 0 if successful.
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* \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if a memory allocation failed.
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* \return #MBEDTLS_ERR_MPI_BAD_INPUT_DATA if \c N is negative or
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* even, or if \c E is negative.
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* \return Another negative error code on different kinds of failures.
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*
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*/
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int mbedtls_mpi_exp_mod_unsafe(mbedtls_mpi *X, const mbedtls_mpi *A,
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const mbedtls_mpi *E, const mbedtls_mpi *N,
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mbedtls_mpi *prec_RR);
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#endif /* bignum_internal.h */
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