4 * \brief Context-independent RSA helper functions
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
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.
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.
21 * There are two classes of helper functions:
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.
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
38 * Copyright (C) 2006-2017, ARM Limited, All Rights Reserved
39 * SPDX-License-Identifier: Apache-2.0
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
45 * http://www.apache.org/licenses/LICENSE-2.0
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.
53 * This file is part of mbed TLS (https://tls.mbed.org)
57 #ifndef MBEDTLS_RSA_INTERNAL_H
58 #define MBEDTLS_RSA_INTERNAL_H
60 #if !defined(MBEDTLS_CONFIG_FILE)
63 #include MBEDTLS_CONFIG_FILE
74 * \brief Compute RSA prime moduli P, Q from public modulus N=PQ
75 * and a pair of private and public key.
77 * \note This is a 'static' helper function not operating on
78 * an RSA context. Alternative implementations need not
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
88 * - 0 if successful. In this case, P and Q constitute a
90 * - A non-zero error code otherwise.
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.
97 int mbedtls_rsa_deduce_primes( mbedtls_mpi const *N, mbedtls_mpi const *E,
99 mbedtls_mpi *P, mbedtls_mpi *Q );
102 * \brief Compute RSA private exponent from
103 * prime moduli and public key.
105 * \note This is a 'static' helper function not operating on
106 * an RSA context. Alternative implementations need not
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.
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.
119 * \note This function does not check whether P and Q are primes.
122 int mbedtls_rsa_deduce_private_exponent( mbedtls_mpi const *P,
123 mbedtls_mpi const *Q,
124 mbedtls_mpi const *E,
129 * \brief Generate RSA-CRT parameters
131 * \note This is a 'static' helper function not operating on
132 * an RSA context. Alternative implementations need not
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.
142 * \return 0 on success, non-zero error code otherwise.
144 * \note This function does not check whether P, Q are
145 * prime and whether D is a valid private exponent.
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 );
154 * \brief Check validity of core RSA parameters
156 * \note This is a 'static' helper function not operating on
157 * an RSA context. Alternative implementations need not
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
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 (%)
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.
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.
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),
190 * \brief Check validity of RSA CRT parameters
192 * \note This is a 'static' helper function not operating on
193 * an RSA context. Alternative implementations need not
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.
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.
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.
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 );
226 #endif /* rsa_internal.h */