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 40 * 41 * Licensed under the Apache License, Version 2.0 (the "License"); you may 42 * not use this file except in compliance with the License. 43 * You may obtain a copy of the License at 44 * 45 * http://www.apache.org/licenses/LICENSE-2.0 46 * 47 * Unless required by applicable law or agreed to in writing, software 48 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 49 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 50 * See the License for the specific language governing permissions and 51 * limitations under the License. 52 * 53 */ 54 55 #ifndef MBEDTLS_RSA_INTERNAL_H 56 #define MBEDTLS_RSA_INTERNAL_H 57 58 #if !defined(MBEDTLS_CONFIG_FILE) 59 #include "mbedtls/config.h" 60 #else 61 #include MBEDTLS_CONFIG_FILE 62 #endif 63 64 #include "mbedtls/bignum.h" 65 66 #ifdef __cplusplus 67 extern "C" { 68 #endif 69 70 71 /** 72 * \brief Compute RSA prime moduli P, Q from public modulus N=PQ 73 * and a pair of private and public key. 74 * 75 * \note This is a 'static' helper function not operating on 76 * an RSA context. Alternative implementations need not 77 * overwrite it. 78 * 79 * \param N RSA modulus N = PQ, with P, Q to be found 80 * \param E RSA public exponent 81 * \param D RSA private exponent 82 * \param P Pointer to MPI holding first prime factor of N on success 83 * \param Q Pointer to MPI holding second prime factor of N on success 84 * 85 * \return 86 * - 0 if successful. In this case, P and Q constitute a 87 * factorization of N. 88 * - A non-zero error code otherwise. 89 * 90 * \note It is neither checked that P, Q are prime nor that 91 * D, E are modular inverses wrt. P-1 and Q-1. For that, 92 * use the helper function \c mbedtls_rsa_validate_params. 93 * 94 */ 95 int mbedtls_rsa_deduce_primes( mbedtls_mpi const *N, mbedtls_mpi const *E, 96 mbedtls_mpi const *D, 97 mbedtls_mpi *P, mbedtls_mpi *Q ); 98 99 /** 100 * \brief Compute RSA private exponent from 101 * prime moduli and public key. 102 * 103 * \note This is a 'static' helper function not operating on 104 * an RSA context. Alternative implementations need not 105 * overwrite it. 106 * 107 * \param P First prime factor of RSA modulus 108 * \param Q Second prime factor of RSA modulus 109 * \param E RSA public exponent 110 * \param D Pointer to MPI holding the private exponent on success. 111 * 112 * \return 113 * - 0 if successful. In this case, D is set to a simultaneous 114 * modular inverse of E modulo both P-1 and Q-1. 115 * - A non-zero error code otherwise. 116 * 117 * \note This function does not check whether P and Q are primes. 118 * 119 */ 120 int mbedtls_rsa_deduce_private_exponent( mbedtls_mpi const *P, 121 mbedtls_mpi const *Q, 122 mbedtls_mpi const *E, 123 mbedtls_mpi *D ); 124 125 126 /** 127 * \brief Generate RSA-CRT parameters 128 * 129 * \note This is a 'static' helper function not operating on 130 * an RSA context. Alternative implementations need not 131 * overwrite it. 132 * 133 * \param P First prime factor of N 134 * \param Q Second prime factor of N 135 * \param D RSA private exponent 136 * \param DP Output variable for D modulo P-1 137 * \param DQ Output variable for D modulo Q-1 138 * \param QP Output variable for the modular inverse of Q modulo P. 139 * 140 * \return 0 on success, non-zero error code otherwise. 141 * 142 * \note This function does not check whether P, Q are 143 * prime and whether D is a valid private exponent. 144 * 145 */ 146 int mbedtls_rsa_deduce_crt( const mbedtls_mpi *P, const mbedtls_mpi *Q, 147 const mbedtls_mpi *D, mbedtls_mpi *DP, 148 mbedtls_mpi *DQ, mbedtls_mpi *QP ); 149 150 151 /** 152 * \brief Check validity of core RSA parameters 153 * 154 * \note This is a 'static' helper function not operating on 155 * an RSA context. Alternative implementations need not 156 * overwrite it. 157 * 158 * \param N RSA modulus N = PQ 159 * \param P First prime factor of N 160 * \param Q Second prime factor of N 161 * \param D RSA private exponent 162 * \param E RSA public exponent 163 * \param f_rng PRNG to be used for primality check, or NULL 164 * \param p_rng PRNG context for f_rng, or NULL 165 * 166 * \return 167 * - 0 if the following conditions are satisfied 168 * if all relevant parameters are provided: 169 * - P prime if f_rng != NULL (%) 170 * - Q prime if f_rng != NULL (%) 171 * - 1 < N = P * Q 172 * - 1 < D, E < N 173 * - D and E are modular inverses modulo P-1 and Q-1 174 * (%) This is only done if MBEDTLS_GENPRIME is defined. 175 * - A non-zero error code otherwise. 176 * 177 * \note The function can be used with a restricted set of arguments 178 * to perform specific checks only. E.g., calling it with 179 * (-,P,-,-,-) and a PRNG amounts to a primality check for P. 180 */ 181 int mbedtls_rsa_validate_params( const mbedtls_mpi *N, const mbedtls_mpi *P, 182 const mbedtls_mpi *Q, const mbedtls_mpi *D, 183 const mbedtls_mpi *E, 184 int (*f_rng)(void *, unsigned char *, size_t), 185 void *p_rng ); 186 187 /** 188 * \brief Check validity of RSA CRT parameters 189 * 190 * \note This is a 'static' helper function not operating on 191 * an RSA context. Alternative implementations need not 192 * overwrite it. 193 * 194 * \param P First prime factor of RSA modulus 195 * \param Q Second prime factor of RSA modulus 196 * \param D RSA private exponent 197 * \param DP MPI to check for D modulo P-1 198 * \param DQ MPI to check for D modulo P-1 199 * \param QP MPI to check for the modular inverse of Q modulo P. 200 * 201 * \return 202 * - 0 if the following conditions are satisfied: 203 * - D = DP mod P-1 if P, D, DP != NULL 204 * - Q = DQ mod P-1 if P, D, DQ != NULL 205 * - QP = Q^-1 mod P if P, Q, QP != NULL 206 * - \c MBEDTLS_ERR_RSA_KEY_CHECK_FAILED if check failed, 207 * potentially including \c MBEDTLS_ERR_MPI_XXX if some 208 * MPI calculations failed. 209 * - \c MBEDTLS_ERR_RSA_BAD_INPUT_DATA if insufficient 210 * data was provided to check DP, DQ or QP. 211 * 212 * \note The function can be used with a restricted set of arguments 213 * to perform specific checks only. E.g., calling it with the 214 * parameters (P, -, D, DP, -, -) will check DP = D mod P-1. 215 */ 216 int mbedtls_rsa_validate_crt( const mbedtls_mpi *P, const mbedtls_mpi *Q, 217 const mbedtls_mpi *D, const mbedtls_mpi *DP, 218 const mbedtls_mpi *DQ, const mbedtls_mpi *QP ); 219 220 #ifdef __cplusplus 221 } 222 #endif 223 224 #endif /* rsa_internal.h */ 225