1 /** 2 * \file rsa_internal.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 #if !defined(MBEDTLS_CONFIG_FILE) 47 #include "mbedtls/config.h" 48 #else 49 #include MBEDTLS_CONFIG_FILE 50 #endif 51 52 #include "mbedtls/bignum.h" 53 54 #ifdef __cplusplus 55 extern "C" { 56 #endif 57 58 59 /** 60 * \brief Compute RSA prime moduli P, Q from public modulus N=PQ 61 * and a pair of private and public key. 62 * 63 * \note This is a 'static' helper function not operating on 64 * an RSA context. Alternative implementations need not 65 * overwrite it. 66 * 67 * \param N RSA modulus N = PQ, with P, Q to be found 68 * \param E RSA public exponent 69 * \param D RSA private exponent 70 * \param P Pointer to MPI holding first prime factor of N on success 71 * \param Q Pointer to MPI holding second prime factor of N on success 72 * 73 * \return 74 * - 0 if successful. In this case, P and Q constitute a 75 * factorization of N. 76 * - A non-zero error code otherwise. 77 * 78 * \note It is neither checked that P, Q are prime nor that 79 * D, E are modular inverses wrt. P-1 and Q-1. For that, 80 * use the helper function \c mbedtls_rsa_validate_params. 81 * 82 */ 83 int mbedtls_rsa_deduce_primes(mbedtls_mpi const *N, mbedtls_mpi const *E, 84 mbedtls_mpi const *D, 85 mbedtls_mpi *P, mbedtls_mpi *Q); 86 87 /** 88 * \brief Compute RSA private exponent from 89 * prime moduli and public key. 90 * 91 * \note This is a 'static' helper function not operating on 92 * an RSA context. Alternative implementations need not 93 * overwrite it. 94 * 95 * \param P First prime factor of RSA modulus 96 * \param Q Second prime factor of RSA modulus 97 * \param E RSA public exponent 98 * \param D Pointer to MPI holding the private exponent on success. 99 * 100 * \return 101 * - 0 if successful. In this case, D is set to a simultaneous 102 * modular inverse of E modulo both P-1 and Q-1. 103 * - A non-zero error code otherwise. 104 * 105 * \note This function does not check whether P and Q are primes. 106 * 107 */ 108 int mbedtls_rsa_deduce_private_exponent(mbedtls_mpi const *P, 109 mbedtls_mpi const *Q, 110 mbedtls_mpi const *E, 111 mbedtls_mpi *D); 112 113 114 /** 115 * \brief Generate RSA-CRT parameters 116 * 117 * \note This is a 'static' helper function not operating on 118 * an RSA context. Alternative implementations need not 119 * overwrite it. 120 * 121 * \param P First prime factor of N 122 * \param Q Second prime factor of N 123 * \param D RSA private exponent 124 * \param DP Output variable for D modulo P-1 125 * \param DQ Output variable for D modulo Q-1 126 * \param QP Output variable for the modular inverse of Q modulo P. 127 * 128 * \return 0 on success, non-zero error code otherwise. 129 * 130 * \note This function does not check whether P, Q are 131 * prime and whether D is a valid private exponent. 132 * 133 */ 134 int mbedtls_rsa_deduce_crt(const mbedtls_mpi *P, const mbedtls_mpi *Q, 135 const mbedtls_mpi *D, mbedtls_mpi *DP, 136 mbedtls_mpi *DQ, mbedtls_mpi *QP); 137 138 139 /** 140 * \brief Check validity of core RSA parameters 141 * 142 * \note This is a 'static' helper function not operating on 143 * an RSA context. Alternative implementations need not 144 * overwrite it. 145 * 146 * \param N RSA modulus N = PQ 147 * \param P First prime factor of N 148 * \param Q Second prime factor of N 149 * \param D RSA private exponent 150 * \param E RSA public exponent 151 * \param f_rng PRNG to be used for primality check, or NULL 152 * \param p_rng PRNG context for f_rng, or NULL 153 * 154 * \return 155 * - 0 if the following conditions are satisfied 156 * if all relevant parameters are provided: 157 * - P prime if f_rng != NULL (%) 158 * - Q prime if f_rng != NULL (%) 159 * - 1 < N = P * Q 160 * - 1 < D, E < N 161 * - D and E are modular inverses modulo P-1 and Q-1 162 * (%) This is only done if MBEDTLS_GENPRIME is defined. 163 * - A non-zero error code otherwise. 164 * 165 * \note The function can be used with a restricted set of arguments 166 * to perform specific checks only. E.g., calling it with 167 * (-,P,-,-,-) and a PRNG amounts to a primality check for P. 168 */ 169 int mbedtls_rsa_validate_params(const mbedtls_mpi *N, const mbedtls_mpi *P, 170 const mbedtls_mpi *Q, const mbedtls_mpi *D, 171 const mbedtls_mpi *E, 172 int (*f_rng)(void *, unsigned char *, size_t), 173 void *p_rng); 174 175 /** 176 * \brief Check validity of RSA CRT parameters 177 * 178 * \note This is a 'static' helper function not operating on 179 * an RSA context. Alternative implementations need not 180 * overwrite it. 181 * 182 * \param P First prime factor of RSA modulus 183 * \param Q Second prime factor of RSA modulus 184 * \param D RSA private exponent 185 * \param DP MPI to check for D modulo P-1 186 * \param DQ MPI to check for D modulo P-1 187 * \param QP MPI to check for the modular inverse of Q modulo P. 188 * 189 * \return 190 * - 0 if the following conditions are satisfied: 191 * - D = DP mod P-1 if P, D, DP != NULL 192 * - Q = DQ mod P-1 if P, D, DQ != NULL 193 * - QP = Q^-1 mod P if P, Q, QP != NULL 194 * - \c MBEDTLS_ERR_RSA_KEY_CHECK_FAILED if check failed, 195 * potentially including \c MBEDTLS_ERR_MPI_XXX if some 196 * MPI calculations failed. 197 * - \c MBEDTLS_ERR_RSA_BAD_INPUT_DATA if insufficient 198 * data was provided to check DP, DQ or QP. 199 * 200 * \note The function can be used with a restricted set of arguments 201 * to perform specific checks only. E.g., calling it with the 202 * parameters (P, -, D, DP, -, -) will check DP = D mod P-1. 203 */ 204 int mbedtls_rsa_validate_crt(const mbedtls_mpi *P, const mbedtls_mpi *Q, 205 const mbedtls_mpi *D, const mbedtls_mpi *DP, 206 const mbedtls_mpi *DQ, const mbedtls_mpi *QP); 207 208 #ifdef __cplusplus 209 } 210 #endif 211 212 #endif /* rsa_internal.h */ 213