/** * \file rsa_alt_helpers.h * * \brief Context-independent RSA helper functions * * This module declares some RSA-related helper functions useful when * implementing the RSA interface. These functions are provided in a separate * compilation unit in order to make it easy for designers of alternative RSA * implementations to use them in their own code, as it is conceived that the * functionality they provide will be necessary for most complete * implementations. * * End-users of Mbed TLS who are not providing their own alternative RSA * implementations should not use these functions directly, and should instead * use only the functions declared in rsa.h. * * The interface provided by this module will be maintained through LTS (Long * Term Support) branches of Mbed TLS, but may otherwise be subject to change, * and must be considered an internal interface of the library. * * There are two classes of helper functions: * * (1) Parameter-generating helpers. These are: * - mbedtls_rsa_deduce_primes * - mbedtls_rsa_deduce_private_exponent * - mbedtls_rsa_deduce_crt * Each of these functions takes a set of core RSA parameters and * generates some other, or CRT related parameters. * * (2) Parameter-checking helpers. These are: * - mbedtls_rsa_validate_params * - mbedtls_rsa_validate_crt * They take a set of core or CRT related RSA parameters and check their * validity. * */ /* * Copyright The Mbed TLS Contributors * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later */ #ifndef MBEDTLS_RSA_ALT_HELPERS_H #define MBEDTLS_RSA_ALT_HELPERS_H #include "mbedtls/build_info.h" #include "mbedtls/bignum.h" #ifdef __cplusplus extern "C" { #endif /** * \brief Compute RSA prime moduli P, Q from public modulus N=PQ * and a pair of private and public key. * * \note This is a 'static' helper function not operating on * an RSA context. Alternative implementations need not * overwrite it. * * \param N RSA modulus N = PQ, with P, Q to be found * \param E RSA public exponent * \param D RSA private exponent * \param P Pointer to MPI holding first prime factor of N on success * \param Q Pointer to MPI holding second prime factor of N on success * * \return * - 0 if successful. In this case, P and Q constitute a * factorization of N. * - A non-zero error code otherwise. * * \note It is neither checked that P, Q are prime nor that * D, E are modular inverses wrt. P-1 and Q-1. For that, * use the helper function \c mbedtls_rsa_validate_params. * */ int mbedtls_rsa_deduce_primes(mbedtls_mpi const *N, mbedtls_mpi const *E, mbedtls_mpi const *D, mbedtls_mpi *P, mbedtls_mpi *Q); /** * \brief Compute RSA private exponent from * prime moduli and public key. * * \note This is a 'static' helper function not operating on * an RSA context. Alternative implementations need not * overwrite it. * * \param P First prime factor of RSA modulus * \param Q Second prime factor of RSA modulus * \param E RSA public exponent * \param D Pointer to MPI holding the private exponent on success. * * \return * - 0 if successful. In this case, D is set to a simultaneous * modular inverse of E modulo both P-1 and Q-1. * - A non-zero error code otherwise. * * \note This function does not check whether P and Q are primes. * */ int mbedtls_rsa_deduce_private_exponent(mbedtls_mpi const *P, mbedtls_mpi const *Q, mbedtls_mpi const *E, mbedtls_mpi *D); /** * \brief Generate RSA-CRT parameters * * \note This is a 'static' helper function not operating on * an RSA context. Alternative implementations need not * overwrite it. * * \param P First prime factor of N * \param Q Second prime factor of N * \param D RSA private exponent * \param DP Output variable for D modulo P-1 * \param DQ Output variable for D modulo Q-1 * \param QP Output variable for the modular inverse of Q modulo P. * * \return 0 on success, non-zero error code otherwise. * * \note This function does not check whether P, Q are * prime and whether D is a valid private exponent. * */ int mbedtls_rsa_deduce_crt(const mbedtls_mpi *P, const mbedtls_mpi *Q, const mbedtls_mpi *D, mbedtls_mpi *DP, mbedtls_mpi *DQ, mbedtls_mpi *QP); /** * \brief Check validity of core RSA parameters * * \note This is a 'static' helper function not operating on * an RSA context. Alternative implementations need not * overwrite it. * * \param N RSA modulus N = PQ * \param P First prime factor of N * \param Q Second prime factor of N * \param D RSA private exponent * \param E RSA public exponent * \param f_rng PRNG to be used for primality check, or NULL * \param p_rng PRNG context for f_rng, or NULL * * \return * - 0 if the following conditions are satisfied * if all relevant parameters are provided: * - P prime if f_rng != NULL (%) * - Q prime if f_rng != NULL (%) * - 1 < N = P * Q * - 1 < D, E < N * - D and E are modular inverses modulo P-1 and Q-1 * (%) This is only done if MBEDTLS_GENPRIME is defined. * - A non-zero error code otherwise. * * \note The function can be used with a restricted set of arguments * to perform specific checks only. E.g., calling it with * (-,P,-,-,-) and a PRNG amounts to a primality check for P. */ int mbedtls_rsa_validate_params(const mbedtls_mpi *N, const mbedtls_mpi *P, const mbedtls_mpi *Q, const mbedtls_mpi *D, const mbedtls_mpi *E, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng); /** * \brief Check validity of RSA CRT parameters * * \note This is a 'static' helper function not operating on * an RSA context. Alternative implementations need not * overwrite it. * * \param P First prime factor of RSA modulus * \param Q Second prime factor of RSA modulus * \param D RSA private exponent * \param DP MPI to check for D modulo P-1 * \param DQ MPI to check for D modulo P-1 * \param QP MPI to check for the modular inverse of Q modulo P. * * \return * - 0 if the following conditions are satisfied: * - D = DP mod P-1 if P, D, DP != NULL * - Q = DQ mod P-1 if P, D, DQ != NULL * - QP = Q^-1 mod P if P, Q, QP != NULL * - \c MBEDTLS_ERR_RSA_KEY_CHECK_FAILED if check failed, * potentially including \c MBEDTLS_ERR_MPI_XXX if some * MPI calculations failed. * - \c MBEDTLS_ERR_RSA_BAD_INPUT_DATA if insufficient * data was provided to check DP, DQ or QP. * * \note The function can be used with a restricted set of arguments * to perform specific checks only. E.g., calling it with the * parameters (P, -, D, DP, -, -) will check DP = D mod P-1. */ int mbedtls_rsa_validate_crt(const mbedtls_mpi *P, const mbedtls_mpi *Q, const mbedtls_mpi *D, const mbedtls_mpi *DP, const mbedtls_mpi *DQ, const mbedtls_mpi *QP); #ifdef __cplusplus } #endif #endif /* rsa_alt_helpers.h */
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