| 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 */ |