1 /** 2 * \file rsa_alt_helpers.h 3 * 4 * \brief Context-independent RSA helper functions 5 * 6 * This module declares some RSA-related helper functions useful when 7 * implementing the RSA interface. These functions are provided in a separate 8 * compilation unit in order to make it easy for designers of alternative RSA 9 * implementations to use them in their own code, as it is conceived that the 10 * functionality they provide will be necessary for most complete 11 * implementations. 12 * 13 * End-users of Mbed TLS who are not providing their own alternative RSA 14 * implementations should not use these functions directly, and should instead 15 * use only the functions declared in rsa.h. 16 * 17 * The interface provided by this module will be maintained through LTS (Long 18 * Term Support) branches of Mbed TLS, but may otherwise be subject to change, 19 * and must be considered an internal interface of the library. 20 * 21 * There are two classes of helper functions: 22 * 23 * (1) Parameter-generating helpers. These are: 24 * - mbedtls_rsa_deduce_primes 25 * - mbedtls_rsa_deduce_private_exponent 26 * - mbedtls_rsa_deduce_crt 27 * Each of these functions takes a set of core RSA parameters and 28 * generates some other, or CRT related parameters. 29 * 30 * (2) Parameter-checking helpers. These are: 31 * - mbedtls_rsa_validate_params 32 * - mbedtls_rsa_validate_crt 33 * They take a set of core or CRT related RSA parameters and check their 34 * validity. 35 * 36 */ 37 /* 38 * Copyright The Mbed TLS Contributors 39 * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later 40 * 41 */ 42 43 #ifndef MBEDTLS_RSA_INTERNAL_H 44 #define MBEDTLS_RSA_INTERNAL_H 45 46 #include "mbedtls/build_info.h" 47 48 #include "mbedtls/bignum.h" 49 50 #ifdef __cplusplus 51 extern "C" { 52 #endif 53 54 55 /** 56 * \brief Compute RSA prime moduli P, Q from public modulus N=PQ 57 * and a pair of private and public key. 58 * 59 * \note This is a 'static' helper function not operating on 60 * an RSA context. Alternative implementations need not 61 * overwrite it. 62 * 63 * \param N RSA modulus N = PQ, with P, Q to be found 64 * \param E RSA public exponent 65 * \param D RSA private exponent 66 * \param P Pointer to MPI holding first prime factor of N on success 67 * \param Q Pointer to MPI holding second prime factor of N on success 68 * 69 * \return 70 * - 0 if successful. In this case, P and Q constitute a 71 * factorization of N. 72 * - A non-zero error code otherwise. 73 * 74 * \note It is neither checked that P, Q are prime nor that 75 * D, E are modular inverses wrt. P-1 and Q-1. For that, 76 * use the helper function \c mbedtls_rsa_validate_params. 77 * 78 */ 79 int mbedtls_rsa_deduce_primes(mbedtls_mpi const *N, mbedtls_mpi const *E, 80 mbedtls_mpi const *D, 81 mbedtls_mpi *P, mbedtls_mpi *Q); 82 83 /** 84 * \brief Compute RSA private exponent from 85 * prime moduli and public key. 86 * 87 * \note This is a 'static' helper function not operating on 88 * an RSA context. Alternative implementations need not 89 * overwrite it. 90 * 91 * \param P First prime factor of RSA modulus 92 * \param Q Second prime factor of RSA modulus 93 * \param E RSA public exponent 94 * \param D Pointer to MPI holding the private exponent on success. 95 * 96 * \return 97 * - 0 if successful. In this case, D is set to a simultaneous 98 * modular inverse of E modulo both P-1 and Q-1. 99 * - A non-zero error code otherwise. 100 * 101 * \note This function does not check whether P and Q are primes. 102 * 103 */ 104 int mbedtls_rsa_deduce_private_exponent(mbedtls_mpi const *P, 105 mbedtls_mpi const *Q, 106 mbedtls_mpi const *E, 107 mbedtls_mpi *D); 108 109 110 /** 111 * \brief Generate RSA-CRT parameters 112 * 113 * \note This is a 'static' helper function not operating on 114 * an RSA context. Alternative implementations need not 115 * overwrite it. 116 * 117 * \param P First prime factor of N 118 * \param Q Second prime factor of N 119 * \param D RSA private exponent 120 * \param DP Output variable for D modulo P-1 121 * \param DQ Output variable for D modulo Q-1 122 * \param QP Output variable for the modular inverse of Q modulo P. 123 * 124 * \return 0 on success, non-zero error code otherwise. 125 * 126 * \note This function does not check whether P, Q are 127 * prime and whether D is a valid private exponent. 128 * 129 */ 130 int mbedtls_rsa_deduce_crt(const mbedtls_mpi *P, const mbedtls_mpi *Q, 131 const mbedtls_mpi *D, mbedtls_mpi *DP, 132 mbedtls_mpi *DQ, mbedtls_mpi *QP); 133 134 135 /** 136 * \brief Check validity of core RSA parameters 137 * 138 * \note This is a 'static' helper function not operating on 139 * an RSA context. Alternative implementations need not 140 * overwrite it. 141 * 142 * \param N RSA modulus N = PQ 143 * \param P First prime factor of N 144 * \param Q Second prime factor of N 145 * \param D RSA private exponent 146 * \param E RSA public exponent 147 * \param f_rng PRNG to be used for primality check, or NULL 148 * \param p_rng PRNG context for f_rng, or NULL 149 * 150 * \return 151 * - 0 if the following conditions are satisfied 152 * if all relevant parameters are provided: 153 * - P prime if f_rng != NULL (%) 154 * - Q prime if f_rng != NULL (%) 155 * - 1 < N = P * Q 156 * - 1 < D, E < N 157 * - D and E are modular inverses modulo P-1 and Q-1 158 * (%) This is only done if MBEDTLS_GENPRIME is defined. 159 * - A non-zero error code otherwise. 160 * 161 * \note The function can be used with a restricted set of arguments 162 * to perform specific checks only. E.g., calling it with 163 * (-,P,-,-,-) and a PRNG amounts to a primality check for P. 164 */ 165 int mbedtls_rsa_validate_params(const mbedtls_mpi *N, const mbedtls_mpi *P, 166 const mbedtls_mpi *Q, const mbedtls_mpi *D, 167 const mbedtls_mpi *E, 168 int (*f_rng)(void *, unsigned char *, size_t), 169 void *p_rng); 170 171 /** 172 * \brief Check validity of RSA CRT parameters 173 * 174 * \note This is a 'static' helper function not operating on 175 * an RSA context. Alternative implementations need not 176 * overwrite it. 177 * 178 * \param P First prime factor of RSA modulus 179 * \param Q Second prime factor of RSA modulus 180 * \param D RSA private exponent 181 * \param DP MPI to check for D modulo P-1 182 * \param DQ MPI to check for D modulo P-1 183 * \param QP MPI to check for the modular inverse of Q modulo P. 184 * 185 * \return 186 * - 0 if the following conditions are satisfied: 187 * - D = DP mod P-1 if P, D, DP != NULL 188 * - Q = DQ mod P-1 if P, D, DQ != NULL 189 * - QP = Q^-1 mod P if P, Q, QP != NULL 190 * - \c MBEDTLS_ERR_RSA_KEY_CHECK_FAILED if check failed, 191 * potentially including \c MBEDTLS_ERR_MPI_XXX if some 192 * MPI calculations failed. 193 * - \c MBEDTLS_ERR_RSA_BAD_INPUT_DATA if insufficient 194 * data was provided to check DP, DQ or QP. 195 * 196 * \note The function can be used with a restricted set of arguments 197 * to perform specific checks only. E.g., calling it with the 198 * parameters (P, -, D, DP, -, -) will check DP = D mod P-1. 199 */ 200 int mbedtls_rsa_validate_crt(const mbedtls_mpi *P, const mbedtls_mpi *Q, 201 const mbedtls_mpi *D, const mbedtls_mpi *DP, 202 const mbedtls_mpi *DQ, const mbedtls_mpi *QP); 203 204 #ifdef __cplusplus 205 } 206 #endif 207 208 #endif /* rsa_alt_helpers.h */ 209
