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 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 #include "mbedtls/build_info.h" 59 60 #include "mbedtls/bignum.h" 61 62 #ifdef __cplusplus 63 extern "C" { 64 #endif 65 66 67 /** 68 * \brief Compute RSA prime moduli P, Q from public modulus N=PQ 69 * and a pair of private and public key. 70 * 71 * \note This is a 'static' helper function not operating on 72 * an RSA context. Alternative implementations need not 73 * overwrite it. 74 * 75 * \param N RSA modulus N = PQ, with P, Q to be found 76 * \param E RSA public exponent 77 * \param D RSA private exponent 78 * \param P Pointer to MPI holding first prime factor of N on success 79 * \param Q Pointer to MPI holding second prime factor of N on success 80 * 81 * \return 82 * - 0 if successful. In this case, P and Q constitute a 83 * factorization of N. 84 * - A non-zero error code otherwise. 85 * 86 * \note It is neither checked that P, Q are prime nor that 87 * D, E are modular inverses wrt. P-1 and Q-1. For that, 88 * use the helper function \c mbedtls_rsa_validate_params. 89 * 90 */ 91 int mbedtls_rsa_deduce_primes( mbedtls_mpi const *N, mbedtls_mpi const *E, 92 mbedtls_mpi const *D, 93 mbedtls_mpi *P, mbedtls_mpi *Q ); 94 95 /** 96 * \brief Compute RSA private exponent from 97 * prime moduli and public key. 98 * 99 * \note This is a 'static' helper function not operating on 100 * an RSA context. Alternative implementations need not 101 * overwrite it. 102 * 103 * \param P First prime factor of RSA modulus 104 * \param Q Second prime factor of RSA modulus 105 * \param E RSA public exponent 106 * \param D Pointer to MPI holding the private exponent on success. 107 * 108 * \return 109 * - 0 if successful. In this case, D is set to a simultaneous 110 * modular inverse of E modulo both P-1 and Q-1. 111 * - A non-zero error code otherwise. 112 * 113 * \note This function does not check whether P and Q are primes. 114 * 115 */ 116 int mbedtls_rsa_deduce_private_exponent( mbedtls_mpi const *P, 117 mbedtls_mpi const *Q, 118 mbedtls_mpi const *E, 119 mbedtls_mpi *D ); 120 121 122 /** 123 * \brief Generate RSA-CRT parameters 124 * 125 * \note This is a 'static' helper function not operating on 126 * an RSA context. Alternative implementations need not 127 * overwrite it. 128 * 129 * \param P First prime factor of N 130 * \param Q Second prime factor of N 131 * \param D RSA private exponent 132 * \param DP Output variable for D modulo P-1 133 * \param DQ Output variable for D modulo Q-1 134 * \param QP Output variable for the modular inverse of Q modulo P. 135 * 136 * \return 0 on success, non-zero error code otherwise. 137 * 138 * \note This function does not check whether P, Q are 139 * prime and whether D is a valid private exponent. 140 * 141 */ 142 int mbedtls_rsa_deduce_crt( const mbedtls_mpi *P, const mbedtls_mpi *Q, 143 const mbedtls_mpi *D, mbedtls_mpi *DP, 144 mbedtls_mpi *DQ, mbedtls_mpi *QP ); 145 146 147 /** 148 * \brief Check validity of core RSA parameters 149 * 150 * \note This is a 'static' helper function not operating on 151 * an RSA context. Alternative implementations need not 152 * overwrite it. 153 * 154 * \param N RSA modulus N = PQ 155 * \param P First prime factor of N 156 * \param Q Second prime factor of N 157 * \param D RSA private exponent 158 * \param E RSA public exponent 159 * \param f_rng PRNG to be used for primality check, or NULL 160 * \param p_rng PRNG context for f_rng, or NULL 161 * 162 * \return 163 * - 0 if the following conditions are satisfied 164 * if all relevant parameters are provided: 165 * - P prime if f_rng != NULL (%) 166 * - Q prime if f_rng != NULL (%) 167 * - 1 < N = P * Q 168 * - 1 < D, E < N 169 * - D and E are modular inverses modulo P-1 and Q-1 170 * (%) This is only done if MBEDTLS_GENPRIME is defined. 171 * - A non-zero error code otherwise. 172 * 173 * \note The function can be used with a restricted set of arguments 174 * to perform specific checks only. E.g., calling it with 175 * (-,P,-,-,-) and a PRNG amounts to a primality check for P. 176 */ 177 int mbedtls_rsa_validate_params( const mbedtls_mpi *N, const mbedtls_mpi *P, 178 const mbedtls_mpi *Q, const mbedtls_mpi *D, 179 const mbedtls_mpi *E, 180 int (*f_rng)(void *, unsigned char *, size_t), 181 void *p_rng ); 182 183 /** 184 * \brief Check validity of RSA CRT parameters 185 * 186 * \note This is a 'static' helper function not operating on 187 * an RSA context. Alternative implementations need not 188 * overwrite it. 189 * 190 * \param P First prime factor of RSA modulus 191 * \param Q Second prime factor of RSA modulus 192 * \param D RSA private exponent 193 * \param DP MPI to check for D modulo P-1 194 * \param DQ MPI to check for D modulo P-1 195 * \param QP MPI to check for the modular inverse of Q modulo P. 196 * 197 * \return 198 * - 0 if the following conditions are satisfied: 199 * - D = DP mod P-1 if P, D, DP != NULL 200 * - Q = DQ mod P-1 if P, D, DQ != NULL 201 * - QP = Q^-1 mod P if P, Q, QP != NULL 202 * - \c MBEDTLS_ERR_RSA_KEY_CHECK_FAILED if check failed, 203 * potentially including \c MBEDTLS_ERR_MPI_XXX if some 204 * MPI calculations failed. 205 * - \c MBEDTLS_ERR_RSA_BAD_INPUT_DATA if insufficient 206 * data was provided to check DP, DQ or QP. 207 * 208 * \note The function can be used with a restricted set of arguments 209 * to perform specific checks only. E.g., calling it with the 210 * parameters (P, -, D, DP, -, -) will check DP = D mod P-1. 211 */ 212 int mbedtls_rsa_validate_crt( const mbedtls_mpi *P, const mbedtls_mpi *Q, 213 const mbedtls_mpi *D, const mbedtls_mpi *DP, 214 const mbedtls_mpi *DQ, const mbedtls_mpi *QP ); 215 216 #ifdef __cplusplus 217 } 218 #endif 219 220 #endif /* rsa_alt_helpers.h */ 221