1 /**
2  * \file rsa.h
3  *
4  * \brief This file provides an API for the RSA public-key cryptosystem.
5  *
6  * The RSA public-key cryptosystem is defined in <em>Public-Key
7  * Cryptography Standards (PKCS) #1 v1.5: RSA Encryption</em>
8  * and <em>Public-Key Cryptography Standards (PKCS) #1 v2.1:
9  * RSA Cryptography Specifications</em>.
10  *
11  */
12 /*
13  *  Copyright The Mbed TLS Contributors
14  *  SPDX-License-Identifier: Apache-2.0
15  *
16  *  Licensed under the Apache License, Version 2.0 (the "License"); you may
17  *  not use this file except in compliance with the License.
18  *  You may obtain a copy of the License at
19  *
20  *  http://www.apache.org/licenses/LICENSE-2.0
21  *
22  *  Unless required by applicable law or agreed to in writing, software
23  *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
24  *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
25  *  See the License for the specific language governing permissions and
26  *  limitations under the License.
27  */
28 #ifndef MBEDTLS_RSA_H
29 #define MBEDTLS_RSA_H
30 #include "mbedtls/private_access.h"
31 
32 #include "mbedtls/build_info.h"
33 
34 #include "mbedtls/bignum.h"
35 #include "mbedtls/md.h"
36 
37 #if defined(MBEDTLS_THREADING_C)
38 #include "mbedtls/threading.h"
39 #endif
40 
41 /*
42  * RSA Error codes
43  */
44 /** Bad input parameters to function. */
45 #define MBEDTLS_ERR_RSA_BAD_INPUT_DATA                    -0x4080
46 /** Input data contains invalid padding and is rejected. */
47 #define MBEDTLS_ERR_RSA_INVALID_PADDING                   -0x4100
48 /** Something failed during generation of a key. */
49 #define MBEDTLS_ERR_RSA_KEY_GEN_FAILED                    -0x4180
50 /** Key failed to pass the validity check of the library. */
51 #define MBEDTLS_ERR_RSA_KEY_CHECK_FAILED                  -0x4200
52 /** The public key operation failed. */
53 #define MBEDTLS_ERR_RSA_PUBLIC_FAILED                     -0x4280
54 /** The private key operation failed. */
55 #define MBEDTLS_ERR_RSA_PRIVATE_FAILED                    -0x4300
56 /** The PKCS#1 verification failed. */
57 #define MBEDTLS_ERR_RSA_VERIFY_FAILED                     -0x4380
58 /** The output buffer for decryption is not large enough. */
59 #define MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE                  -0x4400
60 /** The random generator failed to generate non-zeros. */
61 #define MBEDTLS_ERR_RSA_RNG_FAILED                        -0x4480
62 
63 /*
64  * RSA constants
65  */
66 
67 #define MBEDTLS_RSA_PKCS_V15    0 /**< Use PKCS#1 v1.5 encoding. */
68 #define MBEDTLS_RSA_PKCS_V21    1 /**< Use PKCS#1 v2.1 encoding. */
69 
70 #define MBEDTLS_RSA_SIGN        1 /**< Identifier for RSA signature operations. */
71 #define MBEDTLS_RSA_CRYPT       2 /**< Identifier for RSA encryption and decryption operations. */
72 
73 #define MBEDTLS_RSA_SALT_LEN_ANY    -1
74 
75 /*
76  * The above constants may be used even if the RSA module is compile out,
77  * eg for alternative (PKCS#11) RSA implementations in the PK layers.
78  */
79 
80 #ifdef __cplusplus
81 extern "C" {
82 #endif
83 
84 #if !defined(MBEDTLS_RSA_ALT)
85 // Regular implementation
86 //
87 
88 /**
89  * \brief   The RSA context structure.
90  */
91 typedef struct mbedtls_rsa_context {
92     int MBEDTLS_PRIVATE(ver);                    /*!<  Reserved for internal purposes.
93                                                   *    Do not set this field in application
94                                                   *    code. Its meaning might change without
95                                                   *    notice. */
96     size_t MBEDTLS_PRIVATE(len);                 /*!<  The size of \p N in Bytes. */
97 
98     mbedtls_mpi MBEDTLS_PRIVATE(N);              /*!<  The public modulus. */
99     mbedtls_mpi MBEDTLS_PRIVATE(E);              /*!<  The public exponent. */
100 
101     mbedtls_mpi MBEDTLS_PRIVATE(D);              /*!<  The private exponent. */
102     mbedtls_mpi MBEDTLS_PRIVATE(P);              /*!<  The first prime factor. */
103     mbedtls_mpi MBEDTLS_PRIVATE(Q);              /*!<  The second prime factor. */
104 
105     mbedtls_mpi MBEDTLS_PRIVATE(DP);             /*!<  <code>D % (P - 1)</code>. */
106     mbedtls_mpi MBEDTLS_PRIVATE(DQ);             /*!<  <code>D % (Q - 1)</code>. */
107     mbedtls_mpi MBEDTLS_PRIVATE(QP);             /*!<  <code>1 / (Q % P)</code>. */
108 
109     mbedtls_mpi MBEDTLS_PRIVATE(RN);             /*!<  cached <code>R^2 mod N</code>. */
110 
111     mbedtls_mpi MBEDTLS_PRIVATE(RP);             /*!<  cached <code>R^2 mod P</code>. */
112     mbedtls_mpi MBEDTLS_PRIVATE(RQ);             /*!<  cached <code>R^2 mod Q</code>. */
113 
114     mbedtls_mpi MBEDTLS_PRIVATE(Vi);             /*!<  The cached blinding value. */
115     mbedtls_mpi MBEDTLS_PRIVATE(Vf);             /*!<  The cached un-blinding value. */
116 
117     int MBEDTLS_PRIVATE(padding);                /*!< Selects padding mode:
118                                                   #MBEDTLS_RSA_PKCS_V15 for 1.5 padding and
119                                                   #MBEDTLS_RSA_PKCS_V21 for OAEP or PSS. */
120     int MBEDTLS_PRIVATE(hash_id);                /*!< Hash identifier of mbedtls_md_type_t type,
121                                                     as specified in md.h for use in the MGF
122                                                     mask generating function used in the
123                                                     EME-OAEP and EMSA-PSS encodings. */
124 #if defined(MBEDTLS_THREADING_C)
125     /* Invariant: the mutex is initialized iff ver != 0. */
126     mbedtls_threading_mutex_t MBEDTLS_PRIVATE(mutex);    /*!<  Thread-safety mutex. */
127 #endif
128 }
129 mbedtls_rsa_context;
130 
131 #else  /* MBEDTLS_RSA_ALT */
132 #include "rsa_alt.h"
133 #endif /* MBEDTLS_RSA_ALT */
134 
135 /**
136  * \brief          This function initializes an RSA context.
137  *
138  * \note           This function initializes the padding and the hash
139  *                 identifier to respectively #MBEDTLS_RSA_PKCS_V15 and
140  *                 #MBEDTLS_MD_NONE. See mbedtls_rsa_set_padding() for more
141  *                 information about those parameters.
142  *
143  * \param ctx      The RSA context to initialize. This must not be \c NULL.
144  */
145 void mbedtls_rsa_init(mbedtls_rsa_context *ctx);
146 
147 /**
148  * \brief          This function sets padding for an already initialized RSA
149  *                 context.
150  *
151  * \note           Set padding to #MBEDTLS_RSA_PKCS_V21 for the RSAES-OAEP
152  *                 encryption scheme and the RSASSA-PSS signature scheme.
153  *
154  * \note           The \p hash_id parameter is ignored when using
155  *                 #MBEDTLS_RSA_PKCS_V15 padding.
156  *
157  * \note           The choice of padding mode is strictly enforced for private
158  *                 key operations, since there might be security concerns in
159  *                 mixing padding modes. For public key operations it is
160  *                 a default value, which can be overridden by calling specific
161  *                 \c mbedtls_rsa_rsaes_xxx or \c mbedtls_rsa_rsassa_xxx
162  *                 functions.
163  *
164  * \note           The hash selected in \p hash_id is always used for OEAP
165  *                 encryption. For PSS signatures, it is always used for
166  *                 making signatures, but can be overridden for verifying them.
167  *                 If set to #MBEDTLS_MD_NONE, it is always overridden.
168  *
169  * \param ctx      The initialized RSA context to be configured.
170  * \param padding  The padding mode to use. This must be either
171  *                 #MBEDTLS_RSA_PKCS_V15 or #MBEDTLS_RSA_PKCS_V21.
172  * \param hash_id  The hash identifier for PSS or OAEP, if \p padding is
173  *                 #MBEDTLS_RSA_PKCS_V21. #MBEDTLS_MD_NONE is accepted by this
174  *                 function but may be not suitable for some operations.
175  *                 Ignored if \p padding is #MBEDTLS_RSA_PKCS_V15.
176  *
177  * \return         \c 0 on success.
178  * \return         #MBEDTLS_ERR_RSA_INVALID_PADDING failure:
179  *                 \p padding or \p hash_id is invalid.
180  */
181 int mbedtls_rsa_set_padding(mbedtls_rsa_context *ctx, int padding,
182                             mbedtls_md_type_t hash_id);
183 
184 /**
185  * \brief          This function retrieves padding mode of initialized
186  *                 RSA context.
187  *
188  * \param ctx      The initialized RSA context.
189  *
190  * \return         RSA padding mode.
191  *
192  */
193 int mbedtls_rsa_get_padding_mode(const mbedtls_rsa_context *ctx);
194 
195 /**
196  * \brief          This function retrieves hash identifier of mbedtls_md_type_t
197  *                 type.
198  *
199  * \param ctx      The initialized RSA context.
200  *
201  * \return         Hash identifier of mbedtls_md_type_t type.
202  *
203  */
204 int mbedtls_rsa_get_md_alg(const mbedtls_rsa_context *ctx);
205 
206 /**
207  * \brief          This function imports a set of core parameters into an
208  *                 RSA context.
209  *
210  * \note           This function can be called multiple times for successive
211  *                 imports, if the parameters are not simultaneously present.
212  *
213  *                 Any sequence of calls to this function should be followed
214  *                 by a call to mbedtls_rsa_complete(), which checks and
215  *                 completes the provided information to a ready-for-use
216  *                 public or private RSA key.
217  *
218  * \note           See mbedtls_rsa_complete() for more information on which
219  *                 parameters are necessary to set up a private or public
220  *                 RSA key.
221  *
222  * \note           The imported parameters are copied and need not be preserved
223  *                 for the lifetime of the RSA context being set up.
224  *
225  * \param ctx      The initialized RSA context to store the parameters in.
226  * \param N        The RSA modulus. This may be \c NULL.
227  * \param P        The first prime factor of \p N. This may be \c NULL.
228  * \param Q        The second prime factor of \p N. This may be \c NULL.
229  * \param D        The private exponent. This may be \c NULL.
230  * \param E        The public exponent. This may be \c NULL.
231  *
232  * \return         \c 0 on success.
233  * \return         A non-zero error code on failure.
234  */
235 int mbedtls_rsa_import(mbedtls_rsa_context *ctx,
236                        const mbedtls_mpi *N,
237                        const mbedtls_mpi *P, const mbedtls_mpi *Q,
238                        const mbedtls_mpi *D, const mbedtls_mpi *E);
239 
240 /**
241  * \brief          This function imports core RSA parameters, in raw big-endian
242  *                 binary format, into an RSA context.
243  *
244  * \note           This function can be called multiple times for successive
245  *                 imports, if the parameters are not simultaneously present.
246  *
247  *                 Any sequence of calls to this function should be followed
248  *                 by a call to mbedtls_rsa_complete(), which checks and
249  *                 completes the provided information to a ready-for-use
250  *                 public or private RSA key.
251  *
252  * \note           See mbedtls_rsa_complete() for more information on which
253  *                 parameters are necessary to set up a private or public
254  *                 RSA key.
255  *
256  * \note           The imported parameters are copied and need not be preserved
257  *                 for the lifetime of the RSA context being set up.
258  *
259  * \param ctx      The initialized RSA context to store the parameters in.
260  * \param N        The RSA modulus. This may be \c NULL.
261  * \param N_len    The Byte length of \p N; it is ignored if \p N == NULL.
262  * \param P        The first prime factor of \p N. This may be \c NULL.
263  * \param P_len    The Byte length of \p P; it is ignored if \p P == NULL.
264  * \param Q        The second prime factor of \p N. This may be \c NULL.
265  * \param Q_len    The Byte length of \p Q; it is ignored if \p Q == NULL.
266  * \param D        The private exponent. This may be \c NULL.
267  * \param D_len    The Byte length of \p D; it is ignored if \p D == NULL.
268  * \param E        The public exponent. This may be \c NULL.
269  * \param E_len    The Byte length of \p E; it is ignored if \p E == NULL.
270  *
271  * \return         \c 0 on success.
272  * \return         A non-zero error code on failure.
273  */
274 int mbedtls_rsa_import_raw(mbedtls_rsa_context *ctx,
275                            unsigned char const *N, size_t N_len,
276                            unsigned char const *P, size_t P_len,
277                            unsigned char const *Q, size_t Q_len,
278                            unsigned char const *D, size_t D_len,
279                            unsigned char const *E, size_t E_len);
280 
281 /**
282  * \brief          This function completes an RSA context from
283  *                 a set of imported core parameters.
284  *
285  *                 To setup an RSA public key, precisely \p N and \p E
286  *                 must have been imported.
287  *
288  *                 To setup an RSA private key, sufficient information must
289  *                 be present for the other parameters to be derivable.
290  *
291  *                 The default implementation supports the following:
292  *                 <ul><li>Derive \p P, \p Q from \p N, \p D, \p E.</li>
293  *                 <li>Derive \p N, \p D from \p P, \p Q, \p E.</li></ul>
294  *                 Alternative implementations need not support these.
295  *
296  *                 If this function runs successfully, it guarantees that
297  *                 the RSA context can be used for RSA operations without
298  *                 the risk of failure or crash.
299  *
300  * \warning        This function need not perform consistency checks
301  *                 for the imported parameters. In particular, parameters that
302  *                 are not needed by the implementation might be silently
303  *                 discarded and left unchecked. To check the consistency
304  *                 of the key material, see mbedtls_rsa_check_privkey().
305  *
306  * \param ctx      The initialized RSA context holding imported parameters.
307  *
308  * \return         \c 0 on success.
309  * \return         #MBEDTLS_ERR_RSA_BAD_INPUT_DATA if the attempted derivations
310  *                 failed.
311  *
312  */
313 int mbedtls_rsa_complete(mbedtls_rsa_context *ctx);
314 
315 /**
316  * \brief          This function exports the core parameters of an RSA key.
317  *
318  *                 If this function runs successfully, the non-NULL buffers
319  *                 pointed to by \p N, \p P, \p Q, \p D, and \p E are fully
320  *                 written, with additional unused space filled leading by
321  *                 zero Bytes.
322  *
323  *                 Possible reasons for returning
324  *                 #MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED:<ul>
325  *                 <li>An alternative RSA implementation is in use, which
326  *                 stores the key externally, and either cannot or should
327  *                 not export it into RAM.</li>
328  *                 <li>A SW or HW implementation might not support a certain
329  *                 deduction. For example, \p P, \p Q from \p N, \p D,
330  *                 and \p E if the former are not part of the
331  *                 implementation.</li></ul>
332  *
333  *                 If the function fails due to an unsupported operation,
334  *                 the RSA context stays intact and remains usable.
335  *
336  * \param ctx      The initialized RSA context.
337  * \param N        The MPI to hold the RSA modulus.
338  *                 This may be \c NULL if this field need not be exported.
339  * \param P        The MPI to hold the first prime factor of \p N.
340  *                 This may be \c NULL if this field need not be exported.
341  * \param Q        The MPI to hold the second prime factor of \p N.
342  *                 This may be \c NULL if this field need not be exported.
343  * \param D        The MPI to hold the private exponent.
344  *                 This may be \c NULL if this field need not be exported.
345  * \param E        The MPI to hold the public exponent.
346  *                 This may be \c NULL if this field need not be exported.
347  *
348  * \return         \c 0 on success.
349  * \return         #MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED if exporting the
350  *                 requested parameters cannot be done due to missing
351  *                 functionality or because of security policies.
352  * \return         A non-zero return code on any other failure.
353  *
354  */
355 int mbedtls_rsa_export(const mbedtls_rsa_context *ctx,
356                        mbedtls_mpi *N, mbedtls_mpi *P, mbedtls_mpi *Q,
357                        mbedtls_mpi *D, mbedtls_mpi *E);
358 
359 /**
360  * \brief          This function exports core parameters of an RSA key
361  *                 in raw big-endian binary format.
362  *
363  *                 If this function runs successfully, the non-NULL buffers
364  *                 pointed to by \p N, \p P, \p Q, \p D, and \p E are fully
365  *                 written, with additional unused space filled leading by
366  *                 zero Bytes.
367  *
368  *                 Possible reasons for returning
369  *                 #MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED:<ul>
370  *                 <li>An alternative RSA implementation is in use, which
371  *                 stores the key externally, and either cannot or should
372  *                 not export it into RAM.</li>
373  *                 <li>A SW or HW implementation might not support a certain
374  *                 deduction. For example, \p P, \p Q from \p N, \p D,
375  *                 and \p E if the former are not part of the
376  *                 implementation.</li></ul>
377  *                 If the function fails due to an unsupported operation,
378  *                 the RSA context stays intact and remains usable.
379  *
380  * \note           The length parameters are ignored if the corresponding
381  *                 buffer pointers are NULL.
382  *
383  * \param ctx      The initialized RSA context.
384  * \param N        The Byte array to store the RSA modulus,
385  *                 or \c NULL if this field need not be exported.
386  * \param N_len    The size of the buffer for the modulus.
387  * \param P        The Byte array to hold the first prime factor of \p N,
388  *                 or \c NULL if this field need not be exported.
389  * \param P_len    The size of the buffer for the first prime factor.
390  * \param Q        The Byte array to hold the second prime factor of \p N,
391  *                 or \c NULL if this field need not be exported.
392  * \param Q_len    The size of the buffer for the second prime factor.
393  * \param D        The Byte array to hold the private exponent,
394  *                 or \c NULL if this field need not be exported.
395  * \param D_len    The size of the buffer for the private exponent.
396  * \param E        The Byte array to hold the public exponent,
397  *                 or \c NULL if this field need not be exported.
398  * \param E_len    The size of the buffer for the public exponent.
399  *
400  * \return         \c 0 on success.
401  * \return         #MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED if exporting the
402  *                 requested parameters cannot be done due to missing
403  *                 functionality or because of security policies.
404  * \return         A non-zero return code on any other failure.
405  */
406 int mbedtls_rsa_export_raw(const mbedtls_rsa_context *ctx,
407                            unsigned char *N, size_t N_len,
408                            unsigned char *P, size_t P_len,
409                            unsigned char *Q, size_t Q_len,
410                            unsigned char *D, size_t D_len,
411                            unsigned char *E, size_t E_len);
412 
413 /**
414  * \brief          This function exports CRT parameters of a private RSA key.
415  *
416  * \note           Alternative RSA implementations not using CRT-parameters
417  *                 internally can implement this function based on
418  *                 mbedtls_rsa_deduce_opt().
419  *
420  * \param ctx      The initialized RSA context.
421  * \param DP       The MPI to hold \c D modulo `P-1`,
422  *                 or \c NULL if it need not be exported.
423  * \param DQ       The MPI to hold \c D modulo `Q-1`,
424  *                 or \c NULL if it need not be exported.
425  * \param QP       The MPI to hold modular inverse of \c Q modulo \c P,
426  *                 or \c NULL if it need not be exported.
427  *
428  * \return         \c 0 on success.
429  * \return         A non-zero error code on failure.
430  *
431  */
432 int mbedtls_rsa_export_crt(const mbedtls_rsa_context *ctx,
433                            mbedtls_mpi *DP, mbedtls_mpi *DQ, mbedtls_mpi *QP);
434 
435 /**
436  * \brief          This function retrieves the length of RSA modulus in Bytes.
437  *
438  * \param ctx      The initialized RSA context.
439  *
440  * \return         The length of the RSA modulus in Bytes.
441  *
442  */
443 size_t mbedtls_rsa_get_len(const mbedtls_rsa_context *ctx);
444 
445 /**
446  * \brief          This function generates an RSA keypair.
447  *
448  * \note           mbedtls_rsa_init() must be called before this function,
449  *                 to set up the RSA context.
450  *
451  * \param ctx      The initialized RSA context used to hold the key.
452  * \param f_rng    The RNG function to be used for key generation.
453  *                 This is mandatory and must not be \c NULL.
454  * \param p_rng    The RNG context to be passed to \p f_rng.
455  *                 This may be \c NULL if \p f_rng doesn't need a context.
456  * \param nbits    The size of the public key in bits.
457  * \param exponent The public exponent to use. For example, \c 65537.
458  *                 This must be odd and greater than \c 1.
459  *
460  * \return         \c 0 on success.
461  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
462  */
463 int mbedtls_rsa_gen_key(mbedtls_rsa_context *ctx,
464                         int (*f_rng)(void *, unsigned char *, size_t),
465                         void *p_rng,
466                         unsigned int nbits, int exponent);
467 
468 /**
469  * \brief          This function checks if a context contains at least an RSA
470  *                 public key.
471  *
472  *                 If the function runs successfully, it is guaranteed that
473  *                 enough information is present to perform an RSA public key
474  *                 operation using mbedtls_rsa_public().
475  *
476  * \param ctx      The initialized RSA context to check.
477  *
478  * \return         \c 0 on success.
479  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
480  *
481  */
482 int mbedtls_rsa_check_pubkey(const mbedtls_rsa_context *ctx);
483 
484 /**
485  * \brief      This function checks if a context contains an RSA private key
486  *             and perform basic consistency checks.
487  *
488  * \note       The consistency checks performed by this function not only
489  *             ensure that mbedtls_rsa_private() can be called successfully
490  *             on the given context, but that the various parameters are
491  *             mutually consistent with high probability, in the sense that
492  *             mbedtls_rsa_public() and mbedtls_rsa_private() are inverses.
493  *
494  * \warning    This function should catch accidental misconfigurations
495  *             like swapping of parameters, but it cannot establish full
496  *             trust in neither the quality nor the consistency of the key
497  *             material that was used to setup the given RSA context:
498  *             <ul><li>Consistency: Imported parameters that are irrelevant
499  *             for the implementation might be silently dropped. If dropped,
500  *             the current function does not have access to them,
501  *             and therefore cannot check them. See mbedtls_rsa_complete().
502  *             If you want to check the consistency of the entire
503  *             content of a PKCS1-encoded RSA private key, for example, you
504  *             should use mbedtls_rsa_validate_params() before setting
505  *             up the RSA context.
506  *             Additionally, if the implementation performs empirical checks,
507  *             these checks substantiate but do not guarantee consistency.</li>
508  *             <li>Quality: This function is not expected to perform
509  *             extended quality assessments like checking that the prime
510  *             factors are safe. Additionally, it is the responsibility of the
511  *             user to ensure the trustworthiness of the source of his RSA
512  *             parameters, which goes beyond what is effectively checkable
513  *             by the library.</li></ul>
514  *
515  * \param ctx  The initialized RSA context to check.
516  *
517  * \return     \c 0 on success.
518  * \return     An \c MBEDTLS_ERR_RSA_XXX error code on failure.
519  */
520 int mbedtls_rsa_check_privkey(const mbedtls_rsa_context *ctx);
521 
522 /**
523  * \brief          This function checks a public-private RSA key pair.
524  *
525  *                 It checks each of the contexts, and makes sure they match.
526  *
527  * \param pub      The initialized RSA context holding the public key.
528  * \param prv      The initialized RSA context holding the private key.
529  *
530  * \return         \c 0 on success.
531  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
532  */
533 int mbedtls_rsa_check_pub_priv(const mbedtls_rsa_context *pub,
534                                const mbedtls_rsa_context *prv);
535 
536 /**
537  * \brief          This function performs an RSA public key operation.
538  *
539  * \param ctx      The initialized RSA context to use.
540  * \param input    The input buffer. This must be a readable buffer
541  *                 of length \c ctx->len Bytes. For example, \c 256 Bytes
542  *                 for an 2048-bit RSA modulus.
543  * \param output   The output buffer. This must be a writable buffer
544  *                 of length \c ctx->len Bytes. For example, \c 256 Bytes
545  *                 for an 2048-bit RSA modulus.
546  *
547  * \note           This function does not handle message padding.
548  *
549  * \note           Make sure to set \p input[0] = 0 or ensure that
550  *                 input is smaller than \p N.
551  *
552  * \return         \c 0 on success.
553  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
554  */
555 int mbedtls_rsa_public(mbedtls_rsa_context *ctx,
556                        const unsigned char *input,
557                        unsigned char *output);
558 
559 /**
560  * \brief          This function performs an RSA private key operation.
561  *
562  * \note           Blinding is used if and only if a PRNG is provided.
563  *
564  * \note           If blinding is used, both the base of exponentiation
565  *                 and the exponent are blinded, providing protection
566  *                 against some side-channel attacks.
567  *
568  * \warning        It is deprecated and a security risk to not provide
569  *                 a PRNG here and thereby prevent the use of blinding.
570  *                 Future versions of the library may enforce the presence
571  *                 of a PRNG.
572  *
573  * \param ctx      The initialized RSA context to use.
574  * \param f_rng    The RNG function, used for blinding. It is mandatory.
575  * \param p_rng    The RNG context to pass to \p f_rng. This may be \c NULL
576  *                 if \p f_rng doesn't need a context.
577  * \param input    The input buffer. This must be a readable buffer
578  *                 of length \c ctx->len Bytes. For example, \c 256 Bytes
579  *                 for an 2048-bit RSA modulus.
580  * \param output   The output buffer. This must be a writable buffer
581  *                 of length \c ctx->len Bytes. For example, \c 256 Bytes
582  *                 for an 2048-bit RSA modulus.
583  *
584  * \return         \c 0 on success.
585  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
586  *
587  */
588 int mbedtls_rsa_private(mbedtls_rsa_context *ctx,
589                         int (*f_rng)(void *, unsigned char *, size_t),
590                         void *p_rng,
591                         const unsigned char *input,
592                         unsigned char *output);
593 
594 /**
595  * \brief          This function adds the message padding, then performs an RSA
596  *                 operation.
597  *
598  *                 It is the generic wrapper for performing a PKCS#1 encryption
599  *                 operation.
600  *
601  * \param ctx      The initialized RSA context to use.
602  * \param f_rng    The RNG to use. It is used for padding generation
603  *                 and it is mandatory.
604  * \param p_rng    The RNG context to be passed to \p f_rng. May be
605  *                 \c NULL if \p f_rng doesn't need a context argument.
606  * \param ilen     The length of the plaintext in Bytes.
607  * \param input    The input data to encrypt. This must be a readable
608  *                 buffer of size \p ilen Bytes. It may be \c NULL if
609  *                 `ilen == 0`.
610  * \param output   The output buffer. This must be a writable buffer
611  *                 of length \c ctx->len Bytes. For example, \c 256 Bytes
612  *                 for an 2048-bit RSA modulus.
613  *
614  * \return         \c 0 on success.
615  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
616  */
617 int mbedtls_rsa_pkcs1_encrypt(mbedtls_rsa_context *ctx,
618                               int (*f_rng)(void *, unsigned char *, size_t),
619                               void *p_rng,
620                               size_t ilen,
621                               const unsigned char *input,
622                               unsigned char *output);
623 
624 /**
625  * \brief          This function performs a PKCS#1 v1.5 encryption operation
626  *                 (RSAES-PKCS1-v1_5-ENCRYPT).
627  *
628  * \param ctx      The initialized RSA context to use.
629  * \param f_rng    The RNG function to use. It is mandatory and used for
630  *                 padding generation.
631  * \param p_rng    The RNG context to be passed to \p f_rng. This may
632  *                 be \c NULL if \p f_rng doesn't need a context argument.
633  * \param ilen     The length of the plaintext in Bytes.
634  * \param input    The input data to encrypt. This must be a readable
635  *                 buffer of size \p ilen Bytes. It may be \c NULL if
636  *                 `ilen == 0`.
637  * \param output   The output buffer. This must be a writable buffer
638  *                 of length \c ctx->len Bytes. For example, \c 256 Bytes
639  *                 for an 2048-bit RSA modulus.
640  *
641  * \return         \c 0 on success.
642  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
643  */
644 int mbedtls_rsa_rsaes_pkcs1_v15_encrypt(mbedtls_rsa_context *ctx,
645                                         int (*f_rng)(void *, unsigned char *, size_t),
646                                         void *p_rng,
647                                         size_t ilen,
648                                         const unsigned char *input,
649                                         unsigned char *output);
650 
651 /**
652  * \brief            This function performs a PKCS#1 v2.1 OAEP encryption
653  *                   operation (RSAES-OAEP-ENCRYPT).
654  *
655  * \note             The output buffer must be as large as the size
656  *                   of ctx->N. For example, 128 Bytes if RSA-1024 is used.
657  *
658  * \param ctx        The initialized RSA context to use.
659  * \param f_rng      The RNG function to use. This is needed for padding
660  *                   generation and is mandatory.
661  * \param p_rng      The RNG context to be passed to \p f_rng. This may
662  *                   be \c NULL if \p f_rng doesn't need a context argument.
663  * \param label      The buffer holding the custom label to use.
664  *                   This must be a readable buffer of length \p label_len
665  *                   Bytes. It may be \c NULL if \p label_len is \c 0.
666  * \param label_len  The length of the label in Bytes.
667  * \param ilen       The length of the plaintext buffer \p input in Bytes.
668  * \param input      The input data to encrypt. This must be a readable
669  *                   buffer of size \p ilen Bytes. It may be \c NULL if
670  *                   `ilen == 0`.
671  * \param output     The output buffer. This must be a writable buffer
672  *                   of length \c ctx->len Bytes. For example, \c 256 Bytes
673  *                   for an 2048-bit RSA modulus.
674  *
675  * \return           \c 0 on success.
676  * \return           An \c MBEDTLS_ERR_RSA_XXX error code on failure.
677  */
678 int mbedtls_rsa_rsaes_oaep_encrypt(mbedtls_rsa_context *ctx,
679                                    int (*f_rng)(void *, unsigned char *, size_t),
680                                    void *p_rng,
681                                    const unsigned char *label, size_t label_len,
682                                    size_t ilen,
683                                    const unsigned char *input,
684                                    unsigned char *output);
685 
686 /**
687  * \brief          This function performs an RSA operation, then removes the
688  *                 message padding.
689  *
690  *                 It is the generic wrapper for performing a PKCS#1 decryption
691  *                 operation.
692  *
693  * \note           The output buffer length \c output_max_len should be
694  *                 as large as the size \p ctx->len of \p ctx->N (for example,
695  *                 128 Bytes if RSA-1024 is used) to be able to hold an
696  *                 arbitrary decrypted message. If it is not large enough to
697  *                 hold the decryption of the particular ciphertext provided,
698  *                 the function returns \c MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE.
699  *
700  * \param ctx      The initialized RSA context to use.
701  * \param f_rng    The RNG function. This is used for blinding and is
702  *                 mandatory; see mbedtls_rsa_private() for more.
703  * \param p_rng    The RNG context to be passed to \p f_rng. This may be
704  *                 \c NULL if \p f_rng doesn't need a context.
705  * \param olen     The address at which to store the length of
706  *                 the plaintext. This must not be \c NULL.
707  * \param input    The ciphertext buffer. This must be a readable buffer
708  *                 of length \c ctx->len Bytes. For example, \c 256 Bytes
709  *                 for an 2048-bit RSA modulus.
710  * \param output   The buffer used to hold the plaintext. This must
711  *                 be a writable buffer of length \p output_max_len Bytes.
712  * \param output_max_len The length in Bytes of the output buffer \p output.
713  *
714  * \return         \c 0 on success.
715  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
716  */
717 int mbedtls_rsa_pkcs1_decrypt(mbedtls_rsa_context *ctx,
718                               int (*f_rng)(void *, unsigned char *, size_t),
719                               void *p_rng,
720                               size_t *olen,
721                               const unsigned char *input,
722                               unsigned char *output,
723                               size_t output_max_len);
724 
725 /**
726  * \brief          This function performs a PKCS#1 v1.5 decryption
727  *                 operation (RSAES-PKCS1-v1_5-DECRYPT).
728  *
729  * \note           The output buffer length \c output_max_len should be
730  *                 as large as the size \p ctx->len of \p ctx->N, for example,
731  *                 128 Bytes if RSA-1024 is used, to be able to hold an
732  *                 arbitrary decrypted message. If it is not large enough to
733  *                 hold the decryption of the particular ciphertext provided,
734  *                 the function returns #MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE.
735  *
736  * \param ctx      The initialized RSA context to use.
737  * \param f_rng    The RNG function. This is used for blinding and is
738  *                 mandatory; see mbedtls_rsa_private() for more.
739  * \param p_rng    The RNG context to be passed to \p f_rng. This may be
740  *                 \c NULL if \p f_rng doesn't need a context.
741  * \param olen     The address at which to store the length of
742  *                 the plaintext. This must not be \c NULL.
743  * \param input    The ciphertext buffer. This must be a readable buffer
744  *                 of length \c ctx->len Bytes. For example, \c 256 Bytes
745  *                 for an 2048-bit RSA modulus.
746  * \param output   The buffer used to hold the plaintext. This must
747  *                 be a writable buffer of length \p output_max_len Bytes.
748  * \param output_max_len The length in Bytes of the output buffer \p output.
749  *
750  * \return         \c 0 on success.
751  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
752  *
753  */
754 int mbedtls_rsa_rsaes_pkcs1_v15_decrypt(mbedtls_rsa_context *ctx,
755                                         int (*f_rng)(void *, unsigned char *, size_t),
756                                         void *p_rng,
757                                         size_t *olen,
758                                         const unsigned char *input,
759                                         unsigned char *output,
760                                         size_t output_max_len);
761 
762 /**
763  * \brief            This function performs a PKCS#1 v2.1 OAEP decryption
764  *                   operation (RSAES-OAEP-DECRYPT).
765  *
766  * \note             The output buffer length \c output_max_len should be
767  *                   as large as the size \p ctx->len of \p ctx->N, for
768  *                   example, 128 Bytes if RSA-1024 is used, to be able to
769  *                   hold an arbitrary decrypted message. If it is not
770  *                   large enough to hold the decryption of the particular
771  *                   ciphertext provided, the function returns
772  *                   #MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE.
773  *
774  * \param ctx        The initialized RSA context to use.
775  * \param f_rng      The RNG function. This is used for blinding and is
776  *                   mandatory.
777  * \param p_rng      The RNG context to be passed to \p f_rng. This may be
778  *                   \c NULL if \p f_rng doesn't need a context.
779  * \param label      The buffer holding the custom label to use.
780  *                   This must be a readable buffer of length \p label_len
781  *                   Bytes. It may be \c NULL if \p label_len is \c 0.
782  * \param label_len  The length of the label in Bytes.
783  * \param olen       The address at which to store the length of
784  *                   the plaintext. This must not be \c NULL.
785  * \param input      The ciphertext buffer. This must be a readable buffer
786  *                   of length \c ctx->len Bytes. For example, \c 256 Bytes
787  *                   for an 2048-bit RSA modulus.
788  * \param output     The buffer used to hold the plaintext. This must
789  *                   be a writable buffer of length \p output_max_len Bytes.
790  * \param output_max_len The length in Bytes of the output buffer \p output.
791  *
792  * \return         \c 0 on success.
793  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
794  */
795 int mbedtls_rsa_rsaes_oaep_decrypt(mbedtls_rsa_context *ctx,
796                                    int (*f_rng)(void *, unsigned char *, size_t),
797                                    void *p_rng,
798                                    const unsigned char *label, size_t label_len,
799                                    size_t *olen,
800                                    const unsigned char *input,
801                                    unsigned char *output,
802                                    size_t output_max_len);
803 
804 /**
805  * \brief          This function performs a private RSA operation to sign
806  *                 a message digest using PKCS#1.
807  *
808  *                 It is the generic wrapper for performing a PKCS#1
809  *                 signature.
810  *
811  * \note           The \p sig buffer must be as large as the size
812  *                 of \p ctx->N. For example, 128 Bytes if RSA-1024 is used.
813  *
814  * \note           For PKCS#1 v2.1 encoding, see comments on
815  *                 mbedtls_rsa_rsassa_pss_sign() for details on
816  *                 \p md_alg and \p hash_id.
817  *
818  * \param ctx      The initialized RSA context to use.
819  * \param f_rng    The RNG function to use. This is mandatory and
820  *                 must not be \c NULL.
821  * \param p_rng    The RNG context to be passed to \p f_rng. This may be \c NULL
822  *                 if \p f_rng doesn't need a context argument.
823  * \param md_alg   The message-digest algorithm used to hash the original data.
824  *                 Use #MBEDTLS_MD_NONE for signing raw data.
825  * \param hashlen  The length of the message digest or raw data in Bytes.
826  *                 If \p md_alg is not #MBEDTLS_MD_NONE, this must match the
827  *                 output length of the corresponding hash algorithm.
828  * \param hash     The buffer holding the message digest or raw data.
829  *                 This must be a readable buffer of at least \p hashlen Bytes.
830  * \param sig      The buffer to hold the signature. This must be a writable
831  *                 buffer of length \c ctx->len Bytes. For example, \c 256 Bytes
832  *                 for an 2048-bit RSA modulus. A buffer length of
833  *                 #MBEDTLS_MPI_MAX_SIZE is always safe.
834  *
835  * \return         \c 0 if the signing operation was successful.
836  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
837  */
838 int mbedtls_rsa_pkcs1_sign(mbedtls_rsa_context *ctx,
839                            int (*f_rng)(void *, unsigned char *, size_t),
840                            void *p_rng,
841                            mbedtls_md_type_t md_alg,
842                            unsigned int hashlen,
843                            const unsigned char *hash,
844                            unsigned char *sig);
845 
846 /**
847  * \brief          This function performs a PKCS#1 v1.5 signature
848  *                 operation (RSASSA-PKCS1-v1_5-SIGN).
849  *
850  * \param ctx      The initialized RSA context to use.
851  * \param f_rng    The RNG function. This is used for blinding and is
852  *                 mandatory; see mbedtls_rsa_private() for more.
853  * \param p_rng    The RNG context to be passed to \p f_rng. This may be \c NULL
854  *                 if \p f_rng doesn't need a context argument.
855  * \param md_alg   The message-digest algorithm used to hash the original data.
856  *                 Use #MBEDTLS_MD_NONE for signing raw data.
857  * \param hashlen  The length of the message digest or raw data in Bytes.
858  *                 If \p md_alg is not #MBEDTLS_MD_NONE, this must match the
859  *                 output length of the corresponding hash algorithm.
860  * \param hash     The buffer holding the message digest or raw data.
861  *                 This must be a readable buffer of at least \p hashlen Bytes.
862  * \param sig      The buffer to hold the signature. This must be a writable
863  *                 buffer of length \c ctx->len Bytes. For example, \c 256 Bytes
864  *                 for an 2048-bit RSA modulus. A buffer length of
865  *                 #MBEDTLS_MPI_MAX_SIZE is always safe.
866  *
867  * \return         \c 0 if the signing operation was successful.
868  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
869  */
870 int mbedtls_rsa_rsassa_pkcs1_v15_sign(mbedtls_rsa_context *ctx,
871                                       int (*f_rng)(void *, unsigned char *, size_t),
872                                       void *p_rng,
873                                       mbedtls_md_type_t md_alg,
874                                       unsigned int hashlen,
875                                       const unsigned char *hash,
876                                       unsigned char *sig);
877 
878 /**
879  * \brief          This function performs a PKCS#1 v2.1 PSS signature
880  *                 operation (RSASSA-PSS-SIGN).
881  *
882  * \note           The \c hash_id set in \p ctx by calling
883  *                 mbedtls_rsa_set_padding() selects the hash used for the
884  *                 encoding operation and for the mask generation function
885  *                 (MGF1). For more details on the encoding operation and the
886  *                 mask generation function, consult <em>RFC-3447: Public-Key
887  *                 Cryptography Standards (PKCS) #1 v2.1: RSA Cryptography
888  *                 Specifications</em>.
889  *
890  * \note           This function enforces that the provided salt length complies
891  *                 with FIPS 186-4 §5.5 (e) and RFC 8017 (PKCS#1 v2.2) §9.1.1
892  *                 step 3. The constraint is that the hash length plus the salt
893  *                 length plus 2 bytes must be at most the key length. If this
894  *                 constraint is not met, this function returns
895  *                 #MBEDTLS_ERR_RSA_BAD_INPUT_DATA.
896  *
897  * \param ctx      The initialized RSA context to use.
898  * \param f_rng    The RNG function. It is mandatory and must not be \c NULL.
899  * \param p_rng    The RNG context to be passed to \p f_rng. This may be \c NULL
900  *                 if \p f_rng doesn't need a context argument.
901  * \param md_alg   The message-digest algorithm used to hash the original data.
902  *                 Use #MBEDTLS_MD_NONE for signing raw data.
903  * \param hashlen  The length of the message digest or raw data in Bytes.
904  *                 If \p md_alg is not #MBEDTLS_MD_NONE, this must match the
905  *                 output length of the corresponding hash algorithm.
906  * \param hash     The buffer holding the message digest or raw data.
907  *                 This must be a readable buffer of at least \p hashlen Bytes.
908  * \param saltlen  The length of the salt that should be used.
909  *                 If passed #MBEDTLS_RSA_SALT_LEN_ANY, the function will use
910  *                 the largest possible salt length up to the hash length,
911  *                 which is the largest permitted by some standards including
912  *                 FIPS 186-4 §5.5.
913  * \param sig      The buffer to hold the signature. This must be a writable
914  *                 buffer of length \c ctx->len Bytes. For example, \c 256 Bytes
915  *                 for an 2048-bit RSA modulus. A buffer length of
916  *                 #MBEDTLS_MPI_MAX_SIZE is always safe.
917  *
918  * \return         \c 0 if the signing operation was successful.
919  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
920  */
921 int mbedtls_rsa_rsassa_pss_sign_ext(mbedtls_rsa_context *ctx,
922                                     int (*f_rng)(void *, unsigned char *, size_t),
923                                     void *p_rng,
924                                     mbedtls_md_type_t md_alg,
925                                     unsigned int hashlen,
926                                     const unsigned char *hash,
927                                     int saltlen,
928                                     unsigned char *sig);
929 
930 /**
931  * \brief          This function performs a PKCS#1 v2.1 PSS signature
932  *                 operation (RSASSA-PSS-SIGN).
933  *
934  * \note           The \c hash_id set in \p ctx by calling
935  *                 mbedtls_rsa_set_padding() selects the hash used for the
936  *                 encoding operation and for the mask generation function
937  *                 (MGF1). For more details on the encoding operation and the
938  *                 mask generation function, consult <em>RFC-3447: Public-Key
939  *                 Cryptography Standards (PKCS) #1 v2.1: RSA Cryptography
940  *                 Specifications</em>.
941  *
942  * \note           This function always uses the maximum possible salt size,
943  *                 up to the length of the payload hash. This choice of salt
944  *                 size complies with FIPS 186-4 §5.5 (e) and RFC 8017 (PKCS#1
945  *                 v2.2) §9.1.1 step 3. Furthermore this function enforces a
946  *                 minimum salt size which is the hash size minus 2 bytes. If
947  *                 this minimum size is too large given the key size (the salt
948  *                 size, plus the hash size, plus 2 bytes must be no more than
949  *                 the key size in bytes), this function returns
950  *                 #MBEDTLS_ERR_RSA_BAD_INPUT_DATA.
951  *
952  * \param ctx      The initialized RSA context to use.
953  * \param f_rng    The RNG function. It is mandatory and must not be \c NULL.
954  * \param p_rng    The RNG context to be passed to \p f_rng. This may be \c NULL
955  *                 if \p f_rng doesn't need a context argument.
956  * \param md_alg   The message-digest algorithm used to hash the original data.
957  *                 Use #MBEDTLS_MD_NONE for signing raw data.
958  * \param hashlen  The length of the message digest or raw data in Bytes.
959  *                 If \p md_alg is not #MBEDTLS_MD_NONE, this must match the
960  *                 output length of the corresponding hash algorithm.
961  * \param hash     The buffer holding the message digest or raw data.
962  *                 This must be a readable buffer of at least \p hashlen Bytes.
963  * \param sig      The buffer to hold the signature. This must be a writable
964  *                 buffer of length \c ctx->len Bytes. For example, \c 256 Bytes
965  *                 for an 2048-bit RSA modulus. A buffer length of
966  *                 #MBEDTLS_MPI_MAX_SIZE is always safe.
967  *
968  * \return         \c 0 if the signing operation was successful.
969  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
970  */
971 int mbedtls_rsa_rsassa_pss_sign(mbedtls_rsa_context *ctx,
972                                 int (*f_rng)(void *, unsigned char *, size_t),
973                                 void *p_rng,
974                                 mbedtls_md_type_t md_alg,
975                                 unsigned int hashlen,
976                                 const unsigned char *hash,
977                                 unsigned char *sig);
978 
979 /**
980  * \brief          This function performs a public RSA operation and checks
981  *                 the message digest.
982  *
983  *                 This is the generic wrapper for performing a PKCS#1
984  *                 verification.
985  *
986  * \note           For PKCS#1 v2.1 encoding, see comments on
987  *                 mbedtls_rsa_rsassa_pss_verify() about \p md_alg and
988  *                 \p hash_id.
989  *
990  * \param ctx      The initialized RSA public key context to use.
991  * \param md_alg   The message-digest algorithm used to hash the original data.
992  *                 Use #MBEDTLS_MD_NONE for signing raw data.
993  * \param hashlen  The length of the message digest or raw data in Bytes.
994  *                 If \p md_alg is not #MBEDTLS_MD_NONE, this must match the
995  *                 output length of the corresponding hash algorithm.
996  * \param hash     The buffer holding the message digest or raw data.
997  *                 This must be a readable buffer of at least \p hashlen Bytes.
998  * \param sig      The buffer holding the signature. This must be a readable
999  *                 buffer of length \c ctx->len Bytes. For example, \c 256 Bytes
1000  *                 for an 2048-bit RSA modulus.
1001  *
1002  * \return         \c 0 if the verify operation was successful.
1003  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
1004  */
1005 int mbedtls_rsa_pkcs1_verify(mbedtls_rsa_context *ctx,
1006                              mbedtls_md_type_t md_alg,
1007                              unsigned int hashlen,
1008                              const unsigned char *hash,
1009                              const unsigned char *sig);
1010 
1011 /**
1012  * \brief          This function performs a PKCS#1 v1.5 verification
1013  *                 operation (RSASSA-PKCS1-v1_5-VERIFY).
1014  *
1015  * \param ctx      The initialized RSA public key context to use.
1016  * \param md_alg   The message-digest algorithm used to hash the original data.
1017  *                 Use #MBEDTLS_MD_NONE for signing raw data.
1018  * \param hashlen  The length of the message digest or raw data in Bytes.
1019  *                 If \p md_alg is not #MBEDTLS_MD_NONE, this must match the
1020  *                 output length of the corresponding hash algorithm.
1021  * \param hash     The buffer holding the message digest or raw data.
1022  *                 This must be a readable buffer of at least \p hashlen Bytes.
1023  * \param sig      The buffer holding the signature. This must be a readable
1024  *                 buffer of length \c ctx->len Bytes. For example, \c 256 Bytes
1025  *                 for an 2048-bit RSA modulus.
1026  *
1027  * \return         \c 0 if the verify operation was successful.
1028  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
1029  */
1030 int mbedtls_rsa_rsassa_pkcs1_v15_verify(mbedtls_rsa_context *ctx,
1031                                         mbedtls_md_type_t md_alg,
1032                                         unsigned int hashlen,
1033                                         const unsigned char *hash,
1034                                         const unsigned char *sig);
1035 
1036 /**
1037  * \brief          This function performs a PKCS#1 v2.1 PSS verification
1038  *                 operation (RSASSA-PSS-VERIFY).
1039  *
1040  * \note           The \c hash_id set in \p ctx by calling
1041  *                 mbedtls_rsa_set_padding() selects the hash used for the
1042  *                 encoding operation and for the mask generation function
1043  *                 (MGF1). For more details on the encoding operation and the
1044  *                 mask generation function, consult <em>RFC-3447: Public-Key
1045  *                 Cryptography Standards (PKCS) #1 v2.1: RSA Cryptography
1046  *                 Specifications</em>. If the \c hash_id set in \p ctx by
1047  *                 mbedtls_rsa_set_padding() is #MBEDTLS_MD_NONE, the \p md_alg
1048  *                 parameter is used.
1049  *
1050  * \param ctx      The initialized RSA public key context to use.
1051  * \param md_alg   The message-digest algorithm used to hash the original data.
1052  *                 Use #MBEDTLS_MD_NONE for signing raw data.
1053  * \param hashlen  The length of the message digest or raw data in Bytes.
1054  *                 If \p md_alg is not #MBEDTLS_MD_NONE, this must match the
1055  *                 output length of the corresponding hash algorithm.
1056  * \param hash     The buffer holding the message digest or raw data.
1057  *                 This must be a readable buffer of at least \p hashlen Bytes.
1058  * \param sig      The buffer holding the signature. This must be a readable
1059  *                 buffer of length \c ctx->len Bytes. For example, \c 256 Bytes
1060  *                 for an 2048-bit RSA modulus.
1061  *
1062  * \return         \c 0 if the verify operation was successful.
1063  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
1064  */
1065 int mbedtls_rsa_rsassa_pss_verify(mbedtls_rsa_context *ctx,
1066                                   mbedtls_md_type_t md_alg,
1067                                   unsigned int hashlen,
1068                                   const unsigned char *hash,
1069                                   const unsigned char *sig);
1070 
1071 /**
1072  * \brief          This function performs a PKCS#1 v2.1 PSS verification
1073  *                 operation (RSASSA-PSS-VERIFY).
1074  *
1075  * \note           The \p sig buffer must be as large as the size
1076  *                 of \p ctx->N. For example, 128 Bytes if RSA-1024 is used.
1077  *
1078  * \note           The \c hash_id set in \p ctx by mbedtls_rsa_set_padding() is
1079  *                 ignored.
1080  *
1081  * \param ctx      The initialized RSA public key context to use.
1082  * \param md_alg   The message-digest algorithm used to hash the original data.
1083  *                 Use #MBEDTLS_MD_NONE for signing raw data.
1084  * \param hashlen  The length of the message digest or raw data in Bytes.
1085  *                 If \p md_alg is not #MBEDTLS_MD_NONE, this must match the
1086  *                 output length of the corresponding hash algorithm.
1087  * \param hash     The buffer holding the message digest or raw data.
1088  *                 This must be a readable buffer of at least \p hashlen Bytes.
1089  * \param mgf1_hash_id      The message digest algorithm used for the
1090  *                          verification operation and the mask generation
1091  *                          function (MGF1). For more details on the encoding
1092  *                          operation and the mask generation function, consult
1093  *                          <em>RFC-3447: Public-Key Cryptography Standards
1094  *                          (PKCS) #1 v2.1: RSA Cryptography
1095  *                          Specifications</em>.
1096  * \param expected_salt_len The length of the salt used in padding. Use
1097  *                          #MBEDTLS_RSA_SALT_LEN_ANY to accept any salt length.
1098  * \param sig      The buffer holding the signature. This must be a readable
1099  *                 buffer of length \c ctx->len Bytes. For example, \c 256 Bytes
1100  *                 for an 2048-bit RSA modulus.
1101  *
1102  * \return         \c 0 if the verify operation was successful.
1103  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
1104  */
1105 int mbedtls_rsa_rsassa_pss_verify_ext(mbedtls_rsa_context *ctx,
1106                                       mbedtls_md_type_t md_alg,
1107                                       unsigned int hashlen,
1108                                       const unsigned char *hash,
1109                                       mbedtls_md_type_t mgf1_hash_id,
1110                                       int expected_salt_len,
1111                                       const unsigned char *sig);
1112 
1113 /**
1114  * \brief          This function copies the components of an RSA context.
1115  *
1116  * \param dst      The destination context. This must be initialized.
1117  * \param src      The source context. This must be initialized.
1118  *
1119  * \return         \c 0 on success.
1120  * \return         #MBEDTLS_ERR_MPI_ALLOC_FAILED on memory allocation failure.
1121  */
1122 int mbedtls_rsa_copy(mbedtls_rsa_context *dst, const mbedtls_rsa_context *src);
1123 
1124 /**
1125  * \brief          This function frees the components of an RSA key.
1126  *
1127  * \param ctx      The RSA context to free. May be \c NULL, in which case
1128  *                 this function is a no-op. If it is not \c NULL, it must
1129  *                 point to an initialized RSA context.
1130  */
1131 void mbedtls_rsa_free(mbedtls_rsa_context *ctx);
1132 
1133 #if defined(MBEDTLS_SELF_TEST)
1134 
1135 /**
1136  * \brief          The RSA checkup routine.
1137  *
1138  * \return         \c 0 on success.
1139  * \return         \c 1 on failure.
1140  */
1141 int mbedtls_rsa_self_test(int verbose);
1142 
1143 #endif /* MBEDTLS_SELF_TEST */
1144 
1145 #ifdef __cplusplus
1146 }
1147 #endif
1148 
1149 #endif /* rsa.h */
1150