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: GPL-2.0 40 * 41 * This program is free software; you can redistribute it and/or modify 42 * it under the terms of the GNU General Public License as published by 43 * the Free Software Foundation; either version 2 of the License, or 44 * (at your option) any later version. 45 * 46 * This program is distributed in the hope that it will be useful, 47 * but WITHOUT ANY WARRANTY; without even the implied warranty of 48 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 49 * GNU General Public License for more details. 50 * 51 * You should have received a copy of the GNU General Public License along 52 * with this program; if not, write to the Free Software Foundation, Inc., 53 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. 54 * 55 * This file is part of mbed TLS (https://tls.mbed.org) 56 * 57 */ 58 59 #ifndef MBEDTLS_RSA_INTERNAL_H 60 #define MBEDTLS_RSA_INTERNAL_H 61 62 #if !defined(MBEDTLS_CONFIG_FILE) 63 #include "config.h" 64 #else 65 #include MBEDTLS_CONFIG_FILE 66 #endif 67 68 #include "bignum.h" 69 70 #ifdef __cplusplus 71 extern "C" { 72 #endif 73 74 75 /** 76 * \brief Compute RSA prime moduli P, Q from public modulus N=PQ 77 * and a pair of private and public key. 78 * 79 * \note This is a 'static' helper function not operating on 80 * an RSA context. Alternative implementations need not 81 * overwrite it. 82 * 83 * \param N RSA modulus N = PQ, with P, Q to be found 84 * \param E RSA public exponent 85 * \param D RSA private exponent 86 * \param P Pointer to MPI holding first prime factor of N on success 87 * \param Q Pointer to MPI holding second prime factor of N on success 88 * 89 * \return 90 * - 0 if successful. In this case, P and Q constitute a 91 * factorization of N. 92 * - A non-zero error code otherwise. 93 * 94 * \note It is neither checked that P, Q are prime nor that 95 * D, E are modular inverses wrt. P-1 and Q-1. For that, 96 * use the helper function \c mbedtls_rsa_validate_params. 97 * 98 */ 99 int mbedtls_rsa_deduce_primes( mbedtls_mpi const *N, mbedtls_mpi const *E, 100 mbedtls_mpi const *D, 101 mbedtls_mpi *P, mbedtls_mpi *Q ); 102 103 /** 104 * \brief Compute RSA private exponent from 105 * prime moduli and public key. 106 * 107 * \note This is a 'static' helper function not operating on 108 * an RSA context. Alternative implementations need not 109 * overwrite it. 110 * 111 * \param P First prime factor of RSA modulus 112 * \param Q Second prime factor of RSA modulus 113 * \param E RSA public exponent 114 * \param D Pointer to MPI holding the private exponent on success. 115 * 116 * \return 117 * - 0 if successful. In this case, D is set to a simultaneous 118 * modular inverse of E modulo both P-1 and Q-1. 119 * - A non-zero error code otherwise. 120 * 121 * \note This function does not check whether P and Q are primes. 122 * 123 */ 124 int mbedtls_rsa_deduce_private_exponent( mbedtls_mpi const *P, 125 mbedtls_mpi const *Q, 126 mbedtls_mpi const *E, 127 mbedtls_mpi *D ); 128 129 130 /** 131 * \brief Generate RSA-CRT parameters 132 * 133 * \note This is a 'static' helper function not operating on 134 * an RSA context. Alternative implementations need not 135 * overwrite it. 136 * 137 * \param P First prime factor of N 138 * \param Q Second prime factor of N 139 * \param D RSA private exponent 140 * \param DP Output variable for D modulo P-1 141 * \param DQ Output variable for D modulo Q-1 142 * \param QP Output variable for the modular inverse of Q modulo P. 143 * 144 * \return 0 on success, non-zero error code otherwise. 145 * 146 * \note This function does not check whether P, Q are 147 * prime and whether D is a valid private exponent. 148 * 149 */ 150 int mbedtls_rsa_deduce_crt( const mbedtls_mpi *P, const mbedtls_mpi *Q, 151 const mbedtls_mpi *D, mbedtls_mpi *DP, 152 mbedtls_mpi *DQ, mbedtls_mpi *QP ); 153 154 155 /** 156 * \brief Check validity of core RSA parameters 157 * 158 * \note This is a 'static' helper function not operating on 159 * an RSA context. Alternative implementations need not 160 * overwrite it. 161 * 162 * \param N RSA modulus N = PQ 163 * \param P First prime factor of N 164 * \param Q Second prime factor of N 165 * \param D RSA private exponent 166 * \param E RSA public exponent 167 * \param f_rng PRNG to be used for primality check, or NULL 168 * \param p_rng PRNG context for f_rng, or NULL 169 * 170 * \return 171 * - 0 if the following conditions are satisfied 172 * if all relevant parameters are provided: 173 * - P prime if f_rng != NULL (%) 174 * - Q prime if f_rng != NULL (%) 175 * - 1 < N = P * Q 176 * - 1 < D, E < N 177 * - D and E are modular inverses modulo P-1 and Q-1 178 * (%) This is only done if MBEDTLS_GENPRIME is defined. 179 * - A non-zero error code otherwise. 180 * 181 * \note The function can be used with a restricted set of arguments 182 * to perform specific checks only. E.g., calling it with 183 * (-,P,-,-,-) and a PRNG amounts to a primality check for P. 184 */ 185 int mbedtls_rsa_validate_params( const mbedtls_mpi *N, const mbedtls_mpi *P, 186 const mbedtls_mpi *Q, const mbedtls_mpi *D, 187 const mbedtls_mpi *E, 188 int (*f_rng)(void *, unsigned char *, size_t), 189 void *p_rng ); 190 191 /** 192 * \brief Check validity of RSA CRT parameters 193 * 194 * \note This is a 'static' helper function not operating on 195 * an RSA context. Alternative implementations need not 196 * overwrite it. 197 * 198 * \param P First prime factor of RSA modulus 199 * \param Q Second prime factor of RSA modulus 200 * \param D RSA private exponent 201 * \param DP MPI to check for D modulo P-1 202 * \param DQ MPI to check for D modulo P-1 203 * \param QP MPI to check for the modular inverse of Q modulo P. 204 * 205 * \return 206 * - 0 if the following conditions are satisfied: 207 * - D = DP mod P-1 if P, D, DP != NULL 208 * - Q = DQ mod P-1 if P, D, DQ != NULL 209 * - QP = Q^-1 mod P if P, Q, QP != NULL 210 * - \c MBEDTLS_ERR_RSA_KEY_CHECK_FAILED if check failed, 211 * potentially including \c MBEDTLS_ERR_MPI_XXX if some 212 * MPI calculations failed. 213 * - \c MBEDTLS_ERR_RSA_BAD_INPUT_DATA if insufficient 214 * data was provided to check DP, DQ or QP. 215 * 216 * \note The function can be used with a restricted set of arguments 217 * to perform specific checks only. E.g., calling it with the 218 * parameters (P, -, D, DP, -, -) will check DP = D mod P-1. 219 */ 220 int mbedtls_rsa_validate_crt( const mbedtls_mpi *P, const mbedtls_mpi *Q, 221 const mbedtls_mpi *D, const mbedtls_mpi *DP, 222 const mbedtls_mpi *DQ, const mbedtls_mpi *QP ); 223 224 #ifdef __cplusplus 225 } 226 #endif 227 228 #endif /* rsa_internal.h */ 229