208 lines
8.1 KiB
C
208 lines
8.1 KiB
C
/**
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* \file rsa_alt_helpers.h
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*
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* \brief Context-independent RSA helper functions
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*
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* This module declares some RSA-related helper functions useful when
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* implementing the RSA interface. These functions are provided in a separate
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* compilation unit in order to make it easy for designers of alternative RSA
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* implementations to use them in their own code, as it is conceived that the
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* functionality they provide will be necessary for most complete
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* implementations.
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*
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* End-users of Mbed TLS who are not providing their own alternative RSA
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* implementations should not use these functions directly, and should instead
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* use only the functions declared in rsa.h.
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*
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* The interface provided by this module will be maintained through LTS (Long
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* Term Support) branches of Mbed TLS, but may otherwise be subject to change,
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* and must be considered an internal interface of the library.
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*
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* There are two classes of helper functions:
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*
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* (1) Parameter-generating helpers. These are:
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* - mbedtls_rsa_deduce_primes
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* - mbedtls_rsa_deduce_private_exponent
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* - mbedtls_rsa_deduce_crt
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* Each of these functions takes a set of core RSA parameters and
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* generates some other, or CRT related parameters.
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*
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* (2) Parameter-checking helpers. These are:
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* - mbedtls_rsa_validate_params
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* - mbedtls_rsa_validate_crt
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* They take a set of core or CRT related RSA parameters and check their
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* validity.
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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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*/
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#ifndef MBEDTLS_RSA_INTERNAL_H
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#define MBEDTLS_RSA_INTERNAL_H
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#include "mbedtls/build_info.h"
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#include "mbedtls/bignum.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* \brief Compute RSA prime moduli P, Q from public modulus N=PQ
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* and a pair of private and public key.
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*
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* \note This is a 'static' helper function not operating on
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* an RSA context. Alternative implementations need not
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* overwrite it.
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*
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* \param N RSA modulus N = PQ, with P, Q to be found
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* \param E RSA public exponent
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* \param D RSA private exponent
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* \param P Pointer to MPI holding first prime factor of N on success
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* \param Q Pointer to MPI holding second prime factor of N on success
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*
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* \return
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* - 0 if successful. In this case, P and Q constitute a
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* factorization of N.
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* - A non-zero error code otherwise.
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*
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* \note It is neither checked that P, Q are prime nor that
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* D, E are modular inverses wrt. P-1 and Q-1. For that,
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* use the helper function \c mbedtls_rsa_validate_params.
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*
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*/
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int mbedtls_rsa_deduce_primes(mbedtls_mpi const *N, mbedtls_mpi const *E,
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mbedtls_mpi const *D,
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mbedtls_mpi *P, mbedtls_mpi *Q);
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/**
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* \brief Compute RSA private exponent from
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* prime moduli and public key.
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*
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* \note This is a 'static' helper function not operating on
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* an RSA context. Alternative implementations need not
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* overwrite it.
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*
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* \param P First prime factor of RSA modulus
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* \param Q Second prime factor of RSA modulus
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* \param E RSA public exponent
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* \param D Pointer to MPI holding the private exponent on success.
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*
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* \return
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* - 0 if successful. In this case, D is set to a simultaneous
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* modular inverse of E modulo both P-1 and Q-1.
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* - A non-zero error code otherwise.
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*
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* \note This function does not check whether P and Q are primes.
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*
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*/
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int mbedtls_rsa_deduce_private_exponent(mbedtls_mpi const *P,
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mbedtls_mpi const *Q,
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mbedtls_mpi const *E,
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mbedtls_mpi *D);
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/**
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* \brief Generate RSA-CRT parameters
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*
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* \note This is a 'static' helper function not operating on
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* an RSA context. Alternative implementations need not
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* overwrite it.
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*
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* \param P First prime factor of N
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* \param Q Second prime factor of N
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* \param D RSA private exponent
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* \param DP Output variable for D modulo P-1
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* \param DQ Output variable for D modulo Q-1
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* \param QP Output variable for the modular inverse of Q modulo P.
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*
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* \return 0 on success, non-zero error code otherwise.
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*
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* \note This function does not check whether P, Q are
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* prime and whether D is a valid private exponent.
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*
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*/
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int mbedtls_rsa_deduce_crt(const mbedtls_mpi *P, const mbedtls_mpi *Q,
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const mbedtls_mpi *D, mbedtls_mpi *DP,
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mbedtls_mpi *DQ, mbedtls_mpi *QP);
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/**
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* \brief Check validity of core RSA parameters
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*
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* \note This is a 'static' helper function not operating on
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* an RSA context. Alternative implementations need not
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* overwrite it.
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*
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* \param N RSA modulus N = PQ
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* \param P First prime factor of N
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* \param Q Second prime factor of N
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* \param D RSA private exponent
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* \param E RSA public exponent
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* \param f_rng PRNG to be used for primality check, or NULL
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* \param p_rng PRNG context for f_rng, or NULL
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*
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* \return
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* - 0 if the following conditions are satisfied
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* if all relevant parameters are provided:
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* - P prime if f_rng != NULL (%)
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* - Q prime if f_rng != NULL (%)
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* - 1 < N = P * Q
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* - 1 < D, E < N
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* - D and E are modular inverses modulo P-1 and Q-1
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* (%) This is only done if MBEDTLS_GENPRIME is defined.
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* - A non-zero error code otherwise.
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*
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* \note The function can be used with a restricted set of arguments
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* to perform specific checks only. E.g., calling it with
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* (-,P,-,-,-) and a PRNG amounts to a primality check for P.
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*/
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int mbedtls_rsa_validate_params(const mbedtls_mpi *N, const mbedtls_mpi *P,
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const mbedtls_mpi *Q, const mbedtls_mpi *D,
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const mbedtls_mpi *E,
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int (*f_rng)(void *, unsigned char *, size_t),
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void *p_rng);
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/**
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* \brief Check validity of RSA CRT parameters
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*
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* \note This is a 'static' helper function not operating on
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* an RSA context. Alternative implementations need not
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* overwrite it.
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*
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* \param P First prime factor of RSA modulus
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* \param Q Second prime factor of RSA modulus
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* \param D RSA private exponent
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* \param DP MPI to check for D modulo P-1
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* \param DQ MPI to check for D modulo P-1
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* \param QP MPI to check for the modular inverse of Q modulo P.
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*
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* \return
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* - 0 if the following conditions are satisfied:
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* - D = DP mod P-1 if P, D, DP != NULL
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* - Q = DQ mod P-1 if P, D, DQ != NULL
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* - QP = Q^-1 mod P if P, Q, QP != NULL
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* - \c MBEDTLS_ERR_RSA_KEY_CHECK_FAILED if check failed,
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* potentially including \c MBEDTLS_ERR_MPI_XXX if some
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* MPI calculations failed.
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* - \c MBEDTLS_ERR_RSA_BAD_INPUT_DATA if insufficient
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* data was provided to check DP, DQ or QP.
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*
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* \note The function can be used with a restricted set of arguments
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* to perform specific checks only. E.g., calling it with the
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* parameters (P, -, D, DP, -, -) will check DP = D mod P-1.
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*/
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int mbedtls_rsa_validate_crt(const mbedtls_mpi *P, const mbedtls_mpi *Q,
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const mbedtls_mpi *D, const mbedtls_mpi *DP,
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const mbedtls_mpi *DQ, const mbedtls_mpi *QP);
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#ifdef __cplusplus
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}
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#endif
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#endif /* rsa_alt_helpers.h */
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