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 (C) 2006-2017, ARM Limited, All Rights Reserved 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 * This file is part of mbed TLS (https://tls.mbed.org) 54 * 55 */ 56 57 #ifndef MBEDTLS_RSA_INTERNAL_H 58 #define MBEDTLS_RSA_INTERNAL_H 59 60 #if !defined(MBEDTLS_CONFIG_FILE) 61 #include "config.h" 62 #else 63 #include MBEDTLS_CONFIG_FILE 64 #endif 65 66 #include "bignum.h" 67 68 #ifdef __cplusplus 69 extern "C" { 70 #endif 71 72 73 /** 74 * \brief Compute RSA prime moduli P, Q from public modulus N=PQ 75 * and a pair of private and public key. 76 * 77 * \note This is a 'static' helper function not operating on 78 * an RSA context. Alternative implementations need not 79 * overwrite it. 80 * 81 * \param N RSA modulus N = PQ, with P, Q to be found 82 * \param E RSA public exponent 83 * \param D RSA private exponent 84 * \param P Pointer to MPI holding first prime factor of N on success 85 * \param Q Pointer to MPI holding second prime factor of N on success 86 * 87 * \return 88 * - 0 if successful. In this case, P and Q constitute a 89 * factorization of N. 90 * - A non-zero error code otherwise. 91 * 92 * \note It is neither checked that P, Q are prime nor that 93 * D, E are modular inverses wrt. P-1 and Q-1. For that, 94 * use the helper function \c mbedtls_rsa_validate_params. 95 * 96 */ 97 int mbedtls_rsa_deduce_primes( mbedtls_mpi const *N, mbedtls_mpi const *E, 98 mbedtls_mpi const *D, 99 mbedtls_mpi *P, mbedtls_mpi *Q ); 100 101 /** 102 * \brief Compute RSA private exponent from 103 * prime moduli and public key. 104 * 105 * \note This is a 'static' helper function not operating on 106 * an RSA context. Alternative implementations need not 107 * overwrite it. 108 * 109 * \param P First prime factor of RSA modulus 110 * \param Q Second prime factor of RSA modulus 111 * \param E RSA public exponent 112 * \param D Pointer to MPI holding the private exponent on success. 113 * 114 * \return 115 * - 0 if successful. In this case, D is set to a simultaneous 116 * modular inverse of E modulo both P-1 and Q-1. 117 * - A non-zero error code otherwise. 118 * 119 * \note This function does not check whether P and Q are primes. 120 * 121 */ 122 int mbedtls_rsa_deduce_private_exponent( mbedtls_mpi const *P, 123 mbedtls_mpi const *Q, 124 mbedtls_mpi const *E, 125 mbedtls_mpi *D ); 126 127 128 /** 129 * \brief Generate RSA-CRT parameters 130 * 131 * \note This is a 'static' helper function not operating on 132 * an RSA context. Alternative implementations need not 133 * overwrite it. 134 * 135 * \param P First prime factor of N 136 * \param Q Second prime factor of N 137 * \param D RSA private exponent 138 * \param DP Output variable for D modulo P-1 139 * \param DQ Output variable for D modulo Q-1 140 * \param QP Output variable for the modular inverse of Q modulo P. 141 * 142 * \return 0 on success, non-zero error code otherwise. 143 * 144 * \note This function does not check whether P, Q are 145 * prime and whether D is a valid private exponent. 146 * 147 */ 148 int mbedtls_rsa_deduce_crt( const mbedtls_mpi *P, const mbedtls_mpi *Q, 149 const mbedtls_mpi *D, mbedtls_mpi *DP, 150 mbedtls_mpi *DQ, mbedtls_mpi *QP ); 151 152 153 /** 154 * \brief Check validity of core RSA parameters 155 * 156 * \note This is a 'static' helper function not operating on 157 * an RSA context. Alternative implementations need not 158 * overwrite it. 159 * 160 * \param N RSA modulus N = PQ 161 * \param P First prime factor of N 162 * \param Q Second prime factor of N 163 * \param D RSA private exponent 164 * \param E RSA public exponent 165 * \param f_rng PRNG to be used for primality check, or NULL 166 * \param p_rng PRNG context for f_rng, or NULL 167 * 168 * \return 169 * - 0 if the following conditions are satisfied 170 * if all relevant parameters are provided: 171 * - P prime if f_rng != NULL (%) 172 * - Q prime if f_rng != NULL (%) 173 * - 1 < N = P * Q 174 * - 1 < D, E < N 175 * - D and E are modular inverses modulo P-1 and Q-1 176 * (%) This is only done if MBEDTLS_GENPRIME is defined. 177 * - A non-zero error code otherwise. 178 * 179 * \note The function can be used with a restricted set of arguments 180 * to perform specific checks only. E.g., calling it with 181 * (-,P,-,-,-) and a PRNG amounts to a primality check for P. 182 */ 183 int mbedtls_rsa_validate_params( const mbedtls_mpi *N, const mbedtls_mpi *P, 184 const mbedtls_mpi *Q, const mbedtls_mpi *D, 185 const mbedtls_mpi *E, 186 int (*f_rng)(void *, unsigned char *, size_t), 187 void *p_rng ); 188 189 /** 190 * \brief Check validity of RSA CRT parameters 191 * 192 * \note This is a 'static' helper function not operating on 193 * an RSA context. Alternative implementations need not 194 * overwrite it. 195 * 196 * \param P First prime factor of RSA modulus 197 * \param Q Second prime factor of RSA modulus 198 * \param D RSA private exponent 199 * \param DP MPI to check for D modulo P-1 200 * \param DQ MPI to check for D modulo P-1 201 * \param QP MPI to check for the modular inverse of Q modulo P. 202 * 203 * \return 204 * - 0 if the following conditions are satisfied: 205 * - D = DP mod P-1 if P, D, DP != NULL 206 * - Q = DQ mod P-1 if P, D, DQ != NULL 207 * - QP = Q^-1 mod P if P, Q, QP != NULL 208 * - \c MBEDTLS_ERR_RSA_KEY_CHECK_FAILED if check failed, 209 * potentially including \c MBEDTLS_ERR_MPI_XXX if some 210 * MPI calculations failed. 211 * - \c MBEDTLS_ERR_RSA_BAD_INPUT_DATA if insufficient 212 * data was provided to check DP, DQ or QP. 213 * 214 * \note The function can be used with a restricted set of arguments 215 * to perform specific checks only. E.g., calling it with the 216 * parameters (P, -, D, DP, -, -) will check DP = D mod P-1. 217 */ 218 int mbedtls_rsa_validate_crt( const mbedtls_mpi *P, const mbedtls_mpi *Q, 219 const mbedtls_mpi *D, const mbedtls_mpi *DP, 220 const mbedtls_mpi *DQ, const mbedtls_mpi *QP ); 221 222 #ifdef __cplusplus 223 } 224 #endif 225 226 #endif /* rsa_internal.h */ 227