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 
31 #if !defined(MBEDTLS_CONFIG_FILE)
32 #include "mbedtls/config.h"
33 #else
34 #include MBEDTLS_CONFIG_FILE
35 #endif
36 
37 #include "mbedtls/bignum.h"
38 #include "mbedtls/md.h"
39 
40 #if defined(MBEDTLS_THREADING_C)
41 #include "mbedtls/threading.h"
42 #endif
43 
44 /*
45  * RSA Error codes
46  */
47 #define MBEDTLS_ERR_RSA_BAD_INPUT_DATA                    -0x4080  /**< Bad input parameters to function. */
48 #define MBEDTLS_ERR_RSA_INVALID_PADDING                   -0x4100  /**< Input data contains invalid padding and is rejected. */
49 #define MBEDTLS_ERR_RSA_KEY_GEN_FAILED                    -0x4180  /**< Something failed during generation of a key. */
50 #define MBEDTLS_ERR_RSA_KEY_CHECK_FAILED                  -0x4200  /**< Key failed to pass the validity check of the library. */
51 #define MBEDTLS_ERR_RSA_PUBLIC_FAILED                     -0x4280  /**< The public key operation failed. */
52 #define MBEDTLS_ERR_RSA_PRIVATE_FAILED                    -0x4300  /**< The private key operation failed. */
53 #define MBEDTLS_ERR_RSA_VERIFY_FAILED                     -0x4380  /**< The PKCS#1 verification failed. */
54 #define MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE                  -0x4400  /**< The output buffer for decryption is not large enough. */
55 #define MBEDTLS_ERR_RSA_RNG_FAILED                        -0x4480  /**< The random generator failed to generate non-zeros. */
56 
57 /* MBEDTLS_ERR_RSA_UNSUPPORTED_OPERATION is deprecated and should not be used.
58  */
59 #define MBEDTLS_ERR_RSA_UNSUPPORTED_OPERATION             -0x4500  /**< The implementation does not offer the requested operation, for example, because of security violations or lack of functionality. */
60 
61 /* MBEDTLS_ERR_RSA_HW_ACCEL_FAILED is deprecated and should not be used. */
62 #define MBEDTLS_ERR_RSA_HW_ACCEL_FAILED                   -0x4580  /**< RSA hardware accelerator failed. */
63 
64 /*
65  * RSA constants
66  */
67 #define MBEDTLS_RSA_PUBLIC      0 /**< Request private key operation. */
68 #define MBEDTLS_RSA_PRIVATE     1 /**< Request public key operation. */
69 
70 #define MBEDTLS_RSA_PKCS_V15    0 /**< Use PKCS#1 v1.5 encoding. */
71 #define MBEDTLS_RSA_PKCS_V21    1 /**< Use PKCS#1 v2.1 encoding. */
72 
73 #define MBEDTLS_RSA_SIGN        1 /**< Identifier for RSA signature operations. */
74 #define MBEDTLS_RSA_CRYPT       2 /**< Identifier for RSA encryption and decryption operations. */
75 
76 #define MBEDTLS_RSA_SALT_LEN_ANY    -1
77 
78 /*
79  * The above constants may be used even if the RSA module is compile out,
80  * eg for alternative (PKCS#11) RSA implemenations in the PK layers.
81  */
82 
83 #ifdef __cplusplus
84 extern "C" {
85 #endif
86 
87 #if !defined(MBEDTLS_RSA_ALT)
88 // Regular implementation
89 //
90 
91 /**
92  * \brief   The RSA context structure.
93  *
94  * \note    Direct manipulation of the members of this structure
95  *          is deprecated. All manipulation should instead be done through
96  *          the public interface functions.
97  */
98 typedef struct mbedtls_rsa_context
99 {
100     int ver;                    /*!<  Always 0.*/
101     size_t len;                 /*!<  The size of \p N in Bytes. */
102 
103     mbedtls_mpi N;              /*!<  The public modulus. */
104     mbedtls_mpi E;              /*!<  The public exponent. */
105 
106     mbedtls_mpi D;              /*!<  The private exponent. */
107     mbedtls_mpi P;              /*!<  The first prime factor. */
108     mbedtls_mpi Q;              /*!<  The second prime factor. */
109 
110     mbedtls_mpi DP;             /*!<  <code>D % (P - 1)</code>. */
111     mbedtls_mpi DQ;             /*!<  <code>D % (Q - 1)</code>. */
112     mbedtls_mpi QP;             /*!<  <code>1 / (Q % P)</code>. */
113 
114     mbedtls_mpi RN;             /*!<  cached <code>R^2 mod N</code>. */
115 
116     mbedtls_mpi RP;             /*!<  cached <code>R^2 mod P</code>. */
117     mbedtls_mpi RQ;             /*!<  cached <code>R^2 mod Q</code>. */
118 
119     mbedtls_mpi Vi;             /*!<  The cached blinding value. */
120     mbedtls_mpi Vf;             /*!<  The cached un-blinding value. */
121 
122     int padding;                /*!< Selects padding mode:
123                                      #MBEDTLS_RSA_PKCS_V15 for 1.5 padding and
124                                      #MBEDTLS_RSA_PKCS_V21 for OAEP or PSS. */
125     int hash_id;                /*!< Hash identifier of mbedtls_md_type_t type,
126                                      as specified in md.h for use in the MGF
127                                      mask generating function used in the
128                                      EME-OAEP and EMSA-PSS encodings. */
129 #if defined(MBEDTLS_THREADING_C)
130     mbedtls_threading_mutex_t mutex;    /*!<  Thread-safety mutex. */
131 #endif
132 }
133 mbedtls_rsa_context;
134 
135 #else  /* MBEDTLS_RSA_ALT */
136 #include "rsa_alt.h"
137 #endif /* MBEDTLS_RSA_ALT */
138 
139 /**
140  * \brief          This function initializes an RSA context.
141  *
142  * \note           Set padding to #MBEDTLS_RSA_PKCS_V21 for the RSAES-OAEP
143  *                 encryption scheme and the RSASSA-PSS signature scheme.
144  *
145  * \note           The \p hash_id parameter is ignored when using
146  *                 #MBEDTLS_RSA_PKCS_V15 padding.
147  *
148  * \note           The choice of padding mode is strictly enforced for private key
149  *                 operations, since there might be security concerns in
150  *                 mixing padding modes. For public key operations it is
151  *                 a default value, which can be overridden by calling specific
152  *                 \c rsa_rsaes_xxx or \c rsa_rsassa_xxx functions.
153  *
154  * \note           The hash selected in \p hash_id is always used for OEAP
155  *                 encryption. For PSS signatures, it is always used for
156  *                 making signatures, but can be overridden for verifying them.
157  *                 If set to #MBEDTLS_MD_NONE, it is always overridden.
158  *
159  * \param ctx      The RSA context to initialize. This must not be \c NULL.
160  * \param padding  The padding mode to use. This must be either
161  *                 #MBEDTLS_RSA_PKCS_V15 or #MBEDTLS_RSA_PKCS_V21.
162  * \param hash_id  The hash identifier of ::mbedtls_md_type_t type, if
163  *                 \p padding is #MBEDTLS_RSA_PKCS_V21. It is unused
164  *                 otherwise.
165  */
166 void mbedtls_rsa_init( mbedtls_rsa_context *ctx,
167                        int padding,
168                        int hash_id );
169 
170 /**
171  * \brief          This function imports a set of core parameters into an
172  *                 RSA context.
173  *
174  * \note           This function can be called multiple times for successive
175  *                 imports, if the parameters are not simultaneously present.
176  *
177  *                 Any sequence of calls to this function should be followed
178  *                 by a call to mbedtls_rsa_complete(), which checks and
179  *                 completes the provided information to a ready-for-use
180  *                 public or private RSA key.
181  *
182  * \note           See mbedtls_rsa_complete() for more information on which
183  *                 parameters are necessary to set up a private or public
184  *                 RSA key.
185  *
186  * \note           The imported parameters are copied and need not be preserved
187  *                 for the lifetime of the RSA context being set up.
188  *
189  * \param ctx      The initialized RSA context to store the parameters in.
190  * \param N        The RSA modulus. This may be \c NULL.
191  * \param P        The first prime factor of \p N. This may be \c NULL.
192  * \param Q        The second prime factor of \p N. This may be \c NULL.
193  * \param D        The private exponent. This may be \c NULL.
194  * \param E        The public exponent. This may be \c NULL.
195  *
196  * \return         \c 0 on success.
197  * \return         A non-zero error code on failure.
198  */
199 int mbedtls_rsa_import( mbedtls_rsa_context *ctx,
200                         const mbedtls_mpi *N,
201                         const mbedtls_mpi *P, const mbedtls_mpi *Q,
202                         const mbedtls_mpi *D, const mbedtls_mpi *E );
203 
204 /**
205  * \brief          This function imports core RSA parameters, in raw big-endian
206  *                 binary format, into an RSA context.
207  *
208  * \note           This function can be called multiple times for successive
209  *                 imports, if the parameters are not simultaneously present.
210  *
211  *                 Any sequence of calls to this function should be followed
212  *                 by a call to mbedtls_rsa_complete(), which checks and
213  *                 completes the provided information to a ready-for-use
214  *                 public or private RSA key.
215  *
216  * \note           See mbedtls_rsa_complete() for more information on which
217  *                 parameters are necessary to set up a private or public
218  *                 RSA key.
219  *
220  * \note           The imported parameters are copied and need not be preserved
221  *                 for the lifetime of the RSA context being set up.
222  *
223  * \param ctx      The initialized RSA context to store the parameters in.
224  * \param N        The RSA modulus. This may be \c NULL.
225  * \param N_len    The Byte length of \p N; it is ignored if \p N == NULL.
226  * \param P        The first prime factor of \p N. This may be \c NULL.
227  * \param P_len    The Byte length of \p P; it ns ignored if \p P == NULL.
228  * \param Q        The second prime factor of \p N. This may be \c NULL.
229  * \param Q_len    The Byte length of \p Q; it is ignored if \p Q == NULL.
230  * \param D        The private exponent. This may be \c NULL.
231  * \param D_len    The Byte length of \p D; it is ignored if \p D == NULL.
232  * \param E        The public exponent. This may be \c NULL.
233  * \param E_len    The Byte length of \p E; it is ignored if \p E == NULL.
234  *
235  * \return         \c 0 on success.
236  * \return         A non-zero error code on failure.
237  */
238 int mbedtls_rsa_import_raw( mbedtls_rsa_context *ctx,
239                             unsigned char const *N, size_t N_len,
240                             unsigned char const *P, size_t P_len,
241                             unsigned char const *Q, size_t Q_len,
242                             unsigned char const *D, size_t D_len,
243                             unsigned char const *E, size_t E_len );
244 
245 /**
246  * \brief          This function completes an RSA context from
247  *                 a set of imported core parameters.
248  *
249  *                 To setup an RSA public key, precisely \p N and \p E
250  *                 must have been imported.
251  *
252  *                 To setup an RSA private key, sufficient information must
253  *                 be present for the other parameters to be derivable.
254  *
255  *                 The default implementation supports the following:
256  *                 <ul><li>Derive \p P, \p Q from \p N, \p D, \p E.</li>
257  *                 <li>Derive \p N, \p D from \p P, \p Q, \p E.</li></ul>
258  *                 Alternative implementations need not support these.
259  *
260  *                 If this function runs successfully, it guarantees that
261  *                 the RSA context can be used for RSA operations without
262  *                 the risk of failure or crash.
263  *
264  * \warning        This function need not perform consistency checks
265  *                 for the imported parameters. In particular, parameters that
266  *                 are not needed by the implementation might be silently
267  *                 discarded and left unchecked. To check the consistency
268  *                 of the key material, see mbedtls_rsa_check_privkey().
269  *
270  * \param ctx      The initialized RSA context holding imported parameters.
271  *
272  * \return         \c 0 on success.
273  * \return         #MBEDTLS_ERR_RSA_BAD_INPUT_DATA if the attempted derivations
274  *                 failed.
275  *
276  */
277 int mbedtls_rsa_complete( mbedtls_rsa_context *ctx );
278 
279 /**
280  * \brief          This function exports the core parameters of an RSA key.
281  *
282  *                 If this function runs successfully, the non-NULL buffers
283  *                 pointed to by \p N, \p P, \p Q, \p D, and \p E are fully
284  *                 written, with additional unused space filled leading by
285  *                 zero Bytes.
286  *
287  *                 Possible reasons for returning
288  *                 #MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED:<ul>
289  *                 <li>An alternative RSA implementation is in use, which
290  *                 stores the key externally, and either cannot or should
291  *                 not export it into RAM.</li>
292  *                 <li>A SW or HW implementation might not support a certain
293  *                 deduction. For example, \p P, \p Q from \p N, \p D,
294  *                 and \p E if the former are not part of the
295  *                 implementation.</li></ul>
296  *
297  *                 If the function fails due to an unsupported operation,
298  *                 the RSA context stays intact and remains usable.
299  *
300  * \param ctx      The initialized RSA context.
301  * \param N        The MPI to hold the RSA modulus.
302  *                 This may be \c NULL if this field need not be exported.
303  * \param P        The MPI to hold the first prime factor of \p N.
304  *                 This may be \c NULL if this field need not be exported.
305  * \param Q        The MPI to hold the second prime factor of \p N.
306  *                 This may be \c NULL if this field need not be exported.
307  * \param D        The MPI to hold the private exponent.
308  *                 This may be \c NULL if this field need not be exported.
309  * \param E        The MPI to hold the public exponent.
310  *                 This may be \c NULL if this field need not be exported.
311  *
312  * \return         \c 0 on success.
313  * \return         #MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED if exporting the
314  *                 requested parameters cannot be done due to missing
315  *                 functionality or because of security policies.
316  * \return         A non-zero return code on any other failure.
317  *
318  */
319 int mbedtls_rsa_export( const mbedtls_rsa_context *ctx,
320                         mbedtls_mpi *N, mbedtls_mpi *P, mbedtls_mpi *Q,
321                         mbedtls_mpi *D, mbedtls_mpi *E );
322 
323 /**
324  * \brief          This function exports core parameters of an RSA key
325  *                 in raw big-endian binary format.
326  *
327  *                 If this function runs successfully, the non-NULL buffers
328  *                 pointed to by \p N, \p P, \p Q, \p D, and \p E are fully
329  *                 written, with additional unused space filled leading by
330  *                 zero Bytes.
331  *
332  *                 Possible reasons for returning
333  *                 #MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED:<ul>
334  *                 <li>An alternative RSA implementation is in use, which
335  *                 stores the key externally, and either cannot or should
336  *                 not export it into RAM.</li>
337  *                 <li>A SW or HW implementation might not support a certain
338  *                 deduction. For example, \p P, \p Q from \p N, \p D,
339  *                 and \p E if the former are not part of the
340  *                 implementation.</li></ul>
341  *                 If the function fails due to an unsupported operation,
342  *                 the RSA context stays intact and remains usable.
343  *
344  * \note           The length parameters are ignored if the corresponding
345  *                 buffer pointers are NULL.
346  *
347  * \param ctx      The initialized RSA context.
348  * \param N        The Byte array to store the RSA modulus,
349  *                 or \c NULL if this field need not be exported.
350  * \param N_len    The size of the buffer for the modulus.
351  * \param P        The Byte array to hold the first prime factor of \p N,
352  *                 or \c NULL if this field need not be exported.
353  * \param P_len    The size of the buffer for the first prime factor.
354  * \param Q        The Byte array to hold the second prime factor of \p N,
355  *                 or \c NULL if this field need not be exported.
356  * \param Q_len    The size of the buffer for the second prime factor.
357  * \param D        The Byte array to hold the private exponent,
358  *                 or \c NULL if this field need not be exported.
359  * \param D_len    The size of the buffer for the private exponent.
360  * \param E        The Byte array to hold the public exponent,
361  *                 or \c NULL if this field need not be exported.
362  * \param E_len    The size of the buffer for the public exponent.
363  *
364  * \return         \c 0 on success.
365  * \return         #MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED if exporting the
366  *                 requested parameters cannot be done due to missing
367  *                 functionality or because of security policies.
368  * \return         A non-zero return code on any other failure.
369  */
370 int mbedtls_rsa_export_raw( const mbedtls_rsa_context *ctx,
371                             unsigned char *N, size_t N_len,
372                             unsigned char *P, size_t P_len,
373                             unsigned char *Q, size_t Q_len,
374                             unsigned char *D, size_t D_len,
375                             unsigned char *E, size_t E_len );
376 
377 /**
378  * \brief          This function exports CRT parameters of a private RSA key.
379  *
380  * \note           Alternative RSA implementations not using CRT-parameters
381  *                 internally can implement this function based on
382  *                 mbedtls_rsa_deduce_opt().
383  *
384  * \param ctx      The initialized RSA context.
385  * \param DP       The MPI to hold \c D modulo `P-1`,
386  *                 or \c NULL if it need not be exported.
387  * \param DQ       The MPI to hold \c D modulo `Q-1`,
388  *                 or \c NULL if it need not be exported.
389  * \param QP       The MPI to hold modular inverse of \c Q modulo \c P,
390  *                 or \c NULL if it need not be exported.
391  *
392  * \return         \c 0 on success.
393  * \return         A non-zero error code on failure.
394  *
395  */
396 int mbedtls_rsa_export_crt( const mbedtls_rsa_context *ctx,
397                             mbedtls_mpi *DP, mbedtls_mpi *DQ, mbedtls_mpi *QP );
398 
399 /**
400  * \brief          This function sets padding for an already initialized RSA
401  *                 context. See mbedtls_rsa_init() for details.
402  *
403  * \param ctx      The initialized RSA context to be configured.
404  * \param padding  The padding mode to use. This must be either
405  *                 #MBEDTLS_RSA_PKCS_V15 or #MBEDTLS_RSA_PKCS_V21.
406  * \param hash_id  The #MBEDTLS_RSA_PKCS_V21 hash identifier.
407  */
408 void mbedtls_rsa_set_padding( mbedtls_rsa_context *ctx, int padding,
409                               int hash_id );
410 
411 /**
412  * \brief          This function retrieves the length of RSA modulus in Bytes.
413  *
414  * \param ctx      The initialized RSA context.
415  *
416  * \return         The length of the RSA modulus in Bytes.
417  *
418  */
419 size_t mbedtls_rsa_get_len( const mbedtls_rsa_context *ctx );
420 
421 /**
422  * \brief          This function generates an RSA keypair.
423  *
424  * \note           mbedtls_rsa_init() must be called before this function,
425  *                 to set up the RSA context.
426  *
427  * \param ctx      The initialized RSA context used to hold the key.
428  * \param f_rng    The RNG function to be used for key generation.
429  *                 This must not be \c NULL.
430  * \param p_rng    The RNG context to be passed to \p f_rng.
431  *                 This may be \c NULL if \p f_rng doesn't need a context.
432  * \param nbits    The size of the public key in bits.
433  * \param exponent The public exponent to use. For example, \c 65537.
434  *                 This must be odd and greater than \c 1.
435  *
436  * \return         \c 0 on success.
437  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
438  */
439 int mbedtls_rsa_gen_key( mbedtls_rsa_context *ctx,
440                          int (*f_rng)(void *, unsigned char *, size_t),
441                          void *p_rng,
442                          unsigned int nbits, int exponent );
443 
444 /**
445  * \brief          This function checks if a context contains at least an RSA
446  *                 public key.
447  *
448  *                 If the function runs successfully, it is guaranteed that
449  *                 enough information is present to perform an RSA public key
450  *                 operation using mbedtls_rsa_public().
451  *
452  * \param ctx      The initialized RSA context to check.
453  *
454  * \return         \c 0 on success.
455  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
456  *
457  */
458 int mbedtls_rsa_check_pubkey( const mbedtls_rsa_context *ctx );
459 
460 /**
461  * \brief      This function checks if a context contains an RSA private key
462  *             and perform basic consistency checks.
463  *
464  * \note       The consistency checks performed by this function not only
465  *             ensure that mbedtls_rsa_private() can be called successfully
466  *             on the given context, but that the various parameters are
467  *             mutually consistent with high probability, in the sense that
468  *             mbedtls_rsa_public() and mbedtls_rsa_private() are inverses.
469  *
470  * \warning    This function should catch accidental misconfigurations
471  *             like swapping of parameters, but it cannot establish full
472  *             trust in neither the quality nor the consistency of the key
473  *             material that was used to setup the given RSA context:
474  *             <ul><li>Consistency: Imported parameters that are irrelevant
475  *             for the implementation might be silently dropped. If dropped,
476  *             the current function does not have access to them,
477  *             and therefore cannot check them. See mbedtls_rsa_complete().
478  *             If you want to check the consistency of the entire
479  *             content of an PKCS1-encoded RSA private key, for example, you
480  *             should use mbedtls_rsa_validate_params() before setting
481  *             up the RSA context.
482  *             Additionally, if the implementation performs empirical checks,
483  *             these checks substantiate but do not guarantee consistency.</li>
484  *             <li>Quality: This function is not expected to perform
485  *             extended quality assessments like checking that the prime
486  *             factors are safe. Additionally, it is the responsibility of the
487  *             user to ensure the trustworthiness of the source of his RSA
488  *             parameters, which goes beyond what is effectively checkable
489  *             by the library.</li></ul>
490  *
491  * \param ctx  The initialized RSA context to check.
492  *
493  * \return     \c 0 on success.
494  * \return     An \c MBEDTLS_ERR_RSA_XXX error code on failure.
495  */
496 int mbedtls_rsa_check_privkey( const mbedtls_rsa_context *ctx );
497 
498 /**
499  * \brief          This function checks a public-private RSA key pair.
500  *
501  *                 It checks each of the contexts, and makes sure they match.
502  *
503  * \param pub      The initialized RSA context holding the public key.
504  * \param prv      The initialized RSA context holding the private key.
505  *
506  * \return         \c 0 on success.
507  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
508  */
509 int mbedtls_rsa_check_pub_priv( const mbedtls_rsa_context *pub,
510                                 const mbedtls_rsa_context *prv );
511 
512 /**
513  * \brief          This function performs an RSA public key operation.
514  *
515  * \param ctx      The initialized RSA context to use.
516  * \param input    The input buffer. This must be a readable buffer
517  *                 of length \c ctx->len Bytes. For example, \c 256 Bytes
518  *                 for an 2048-bit RSA modulus.
519  * \param output   The output buffer. This must be a writable buffer
520  *                 of length \c ctx->len Bytes. For example, \c 256 Bytes
521  *                 for an 2048-bit RSA modulus.
522  *
523  * \note           This function does not handle message padding.
524  *
525  * \note           Make sure to set \p input[0] = 0 or ensure that
526  *                 input is smaller than \p N.
527  *
528  * \return         \c 0 on success.
529  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
530  */
531 int mbedtls_rsa_public( mbedtls_rsa_context *ctx,
532                 const unsigned char *input,
533                 unsigned char *output );
534 
535 /**
536  * \brief          This function performs an RSA private key operation.
537  *
538  * \note           Blinding is used if and only if a PRNG is provided.
539  *
540  * \note           If blinding is used, both the base of exponentation
541  *                 and the exponent are blinded, providing protection
542  *                 against some side-channel attacks.
543  *
544  * \warning        It is deprecated and a security risk to not provide
545  *                 a PRNG here and thereby prevent the use of blinding.
546  *                 Future versions of the library may enforce the presence
547  *                 of a PRNG.
548  *
549  * \param ctx      The initialized RSA context to use.
550  * \param f_rng    The RNG function, used for blinding. It is discouraged
551  *                 and deprecated to pass \c NULL here, in which case
552  *                 blinding will be omitted.
553  * \param p_rng    The RNG context to pass to \p f_rng. This may be \c NULL
554  *                 if \p f_rng is \c NULL or if \p f_rng doesn't need a context.
555  * \param input    The input buffer. This must be a readable buffer
556  *                 of length \c ctx->len Bytes. For example, \c 256 Bytes
557  *                 for an 2048-bit RSA modulus.
558  * \param output   The output buffer. This must be a writable buffer
559  *                 of length \c ctx->len Bytes. For example, \c 256 Bytes
560  *                 for an 2048-bit RSA modulus.
561  *
562  * \return         \c 0 on success.
563  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
564  *
565  */
566 int mbedtls_rsa_private( mbedtls_rsa_context *ctx,
567                  int (*f_rng)(void *, unsigned char *, size_t),
568                  void *p_rng,
569                  const unsigned char *input,
570                  unsigned char *output );
571 
572 /**
573  * \brief          This function adds the message padding, then performs an RSA
574  *                 operation.
575  *
576  *                 It is the generic wrapper for performing a PKCS#1 encryption
577  *                 operation using the \p mode from the context.
578  *
579  * \deprecated     It is deprecated and discouraged to call this function
580  *                 in #MBEDTLS_RSA_PRIVATE mode. Future versions of the library
581  *                 are likely to remove the \p mode argument and have it
582  *                 implicitly set to #MBEDTLS_RSA_PUBLIC.
583  *
584  * \note           Alternative implementations of RSA need not support
585  *                 mode being set to #MBEDTLS_RSA_PRIVATE and might instead
586  *                 return #MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED.
587  *
588  * \param ctx      The initialized RSA context to use.
589  * \param f_rng    The RNG to use. It is mandatory for PKCS#1 v2.1 padding
590  *                 encoding, and for PKCS#1 v1.5 padding encoding when used
591  *                 with \p mode set to #MBEDTLS_RSA_PUBLIC. For PKCS#1 v1.5
592  *                 padding encoding and \p mode set to #MBEDTLS_RSA_PRIVATE,
593  *                 it is used for blinding and should be provided in this
594  *                 case; see mbedtls_rsa_private() for more.
595  * \param p_rng    The RNG context to be passed to \p f_rng. May be
596  *                 \c NULL if \p f_rng is \c NULL or if \p f_rng doesn't
597  *                 need a context argument.
598  * \param mode     The mode of operation. This must be either
599  *                 #MBEDTLS_RSA_PUBLIC or #MBEDTLS_RSA_PRIVATE (deprecated).
600  * \param ilen     The length of the plaintext in Bytes.
601  * \param input    The input data to encrypt. This must be a readable
602  *                 buffer of size \p ilen Bytes. It may be \c NULL if
603  *                 `ilen == 0`.
604  * \param output   The output buffer. This must be a writable buffer
605  *                 of length \c ctx->len Bytes. For example, \c 256 Bytes
606  *                 for an 2048-bit RSA modulus.
607  *
608  * \return         \c 0 on success.
609  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
610  */
611 int mbedtls_rsa_pkcs1_encrypt( mbedtls_rsa_context *ctx,
612                        int (*f_rng)(void *, unsigned char *, size_t),
613                        void *p_rng,
614                        int mode, size_t ilen,
615                        const unsigned char *input,
616                        unsigned char *output );
617 
618 /**
619  * \brief          This function performs a PKCS#1 v1.5 encryption operation
620  *                 (RSAES-PKCS1-v1_5-ENCRYPT).
621  *
622  * \deprecated     It is deprecated and discouraged to call this function
623  *                 in #MBEDTLS_RSA_PRIVATE mode. Future versions of the library
624  *                 are likely to remove the \p mode argument and have it
625  *                 implicitly set to #MBEDTLS_RSA_PUBLIC.
626  *
627  * \note           Alternative implementations of RSA need not support
628  *                 mode being set to #MBEDTLS_RSA_PRIVATE and might instead
629  *                 return #MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED.
630  *
631  * \param ctx      The initialized RSA context to use.
632  * \param f_rng    The RNG function to use. It is needed for padding generation
633  *                 if \p mode is #MBEDTLS_RSA_PUBLIC. If \p mode is
634  *                 #MBEDTLS_RSA_PRIVATE (discouraged), it is used for
635  *                 blinding and should be provided; see mbedtls_rsa_private().
636  * \param p_rng    The RNG context to be passed to \p f_rng. This may
637  *                 be \c NULL if \p f_rng is \c NULL or if \p f_rng
638  *                 doesn't need a context argument.
639  * \param mode     The mode of operation. This must be either
640  *                 #MBEDTLS_RSA_PUBLIC or #MBEDTLS_RSA_PRIVATE (deprecated).
641  * \param ilen     The length of the plaintext in Bytes.
642  * \param input    The input data to encrypt. This must be a readable
643  *                 buffer of size \p ilen Bytes. It may be \c NULL if
644  *                 `ilen == 0`.
645  * \param output   The output buffer. This must be a writable buffer
646  *                 of length \c ctx->len Bytes. For example, \c 256 Bytes
647  *                 for an 2048-bit RSA modulus.
648  *
649  * \return         \c 0 on success.
650  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
651  */
652 int mbedtls_rsa_rsaes_pkcs1_v15_encrypt( mbedtls_rsa_context *ctx,
653                                  int (*f_rng)(void *, unsigned char *, size_t),
654                                  void *p_rng,
655                                  int mode, size_t ilen,
656                                  const unsigned char *input,
657                                  unsigned char *output );
658 
659 /**
660  * \brief            This function performs a PKCS#1 v2.1 OAEP encryption
661  *                   operation (RSAES-OAEP-ENCRYPT).
662  *
663  * \note             The output buffer must be as large as the size
664  *                   of ctx->N. For example, 128 Bytes if RSA-1024 is used.
665  *
666  * \deprecated       It is deprecated and discouraged to call this function
667  *                   in #MBEDTLS_RSA_PRIVATE mode. Future versions of the library
668  *                   are likely to remove the \p mode argument and have it
669  *                   implicitly set to #MBEDTLS_RSA_PUBLIC.
670  *
671  * \note             Alternative implementations of RSA need not support
672  *                   mode being set to #MBEDTLS_RSA_PRIVATE and might instead
673  *                   return #MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED.
674  *
675  * \param ctx        The initnialized RSA context to use.
676  * \param f_rng      The RNG function to use. This is needed for padding
677  *                   generation and must be provided.
678  * \param p_rng      The RNG context to be passed to \p f_rng. This may
679  *                   be \c NULL if \p f_rng doesn't need a context argument.
680  * \param mode       The mode of operation. This must be either
681  *                   #MBEDTLS_RSA_PUBLIC or #MBEDTLS_RSA_PRIVATE (deprecated).
682  * \param label      The buffer holding the custom label to use.
683  *                   This must be a readable buffer of length \p label_len
684  *                   Bytes. It may be \c NULL if \p label_len is \c 0.
685  * \param label_len  The length of the label in Bytes.
686  * \param ilen       The length of the plaintext buffer \p input in Bytes.
687  * \param input      The input data to encrypt. This must be a readable
688  *                   buffer of size \p ilen Bytes. It may be \c NULL if
689  *                   `ilen == 0`.
690  * \param output     The output buffer. This must be a writable buffer
691  *                   of length \c ctx->len Bytes. For example, \c 256 Bytes
692  *                   for an 2048-bit RSA modulus.
693  *
694  * \return           \c 0 on success.
695  * \return           An \c MBEDTLS_ERR_RSA_XXX error code on failure.
696  */
697 int mbedtls_rsa_rsaes_oaep_encrypt( mbedtls_rsa_context *ctx,
698                             int (*f_rng)(void *, unsigned char *, size_t),
699                             void *p_rng,
700                             int mode,
701                             const unsigned char *label, size_t label_len,
702                             size_t ilen,
703                             const unsigned char *input,
704                             unsigned char *output );
705 
706 /**
707  * \brief          This function performs an RSA operation, then removes the
708  *                 message padding.
709  *
710  *                 It is the generic wrapper for performing a PKCS#1 decryption
711  *                 operation using the \p mode from the context.
712  *
713  * \note           The output buffer length \c output_max_len should be
714  *                 as large as the size \p ctx->len of \p ctx->N (for example,
715  *                 128 Bytes if RSA-1024 is used) to be able to hold an
716  *                 arbitrary decrypted message. If it is not large enough to
717  *                 hold the decryption of the particular ciphertext provided,
718  *                 the function returns \c MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE.
719  *
720  * \deprecated     It is deprecated and discouraged to call this function
721  *                 in #MBEDTLS_RSA_PUBLIC mode. Future versions of the library
722  *                 are likely to remove the \p mode argument and have it
723  *                 implicitly set to #MBEDTLS_RSA_PRIVATE.
724  *
725  * \note           Alternative implementations of RSA need not support
726  *                 mode being set to #MBEDTLS_RSA_PUBLIC and might instead
727  *                 return #MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED.
728  *
729  * \param ctx      The initialized RSA context to use.
730  * \param f_rng    The RNG function. If \p mode is #MBEDTLS_RSA_PRIVATE,
731  *                 this is used for blinding and should be provided; see
732  *                 mbedtls_rsa_private() for more. If \p mode is
733  *                 #MBEDTLS_RSA_PUBLIC, it is ignored.
734  * \param p_rng    The RNG context to be passed to \p f_rng. This may be
735  *                 \c NULL if \p f_rng is \c NULL or doesn't need a context.
736  * \param mode     The mode of operation. This must be either
737  *                 #MBEDTLS_RSA_PRIVATE or #MBEDTLS_RSA_PUBLIC (deprecated).
738  * \param olen     The address at which to store the length of
739  *                 the plaintext. This must not be \c NULL.
740  * \param input    The ciphertext buffer. This must be a readable buffer
741  *                 of length \c ctx->len Bytes. For example, \c 256 Bytes
742  *                 for an 2048-bit RSA modulus.
743  * \param output   The buffer used to hold the plaintext. This must
744  *                 be a writable buffer of length \p output_max_len Bytes.
745  * \param output_max_len The length in Bytes of the output buffer \p output.
746  *
747  * \return         \c 0 on success.
748  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
749  */
750 int mbedtls_rsa_pkcs1_decrypt( mbedtls_rsa_context *ctx,
751                        int (*f_rng)(void *, unsigned char *, size_t),
752                        void *p_rng,
753                        int mode, size_t *olen,
754                        const unsigned char *input,
755                        unsigned char *output,
756                        size_t output_max_len );
757 
758 /**
759  * \brief          This function performs a PKCS#1 v1.5 decryption
760  *                 operation (RSAES-PKCS1-v1_5-DECRYPT).
761  *
762  * \note           The output buffer length \c output_max_len should be
763  *                 as large as the size \p ctx->len of \p ctx->N, for example,
764  *                 128 Bytes if RSA-1024 is used, to be able to hold an
765  *                 arbitrary decrypted message. If it is not large enough to
766  *                 hold the decryption of the particular ciphertext provided,
767  *                 the function returns #MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE.
768  *
769  * \deprecated     It is deprecated and discouraged to call this function
770  *                 in #MBEDTLS_RSA_PUBLIC mode. Future versions of the library
771  *                 are likely to remove the \p mode argument and have it
772  *                 implicitly set to #MBEDTLS_RSA_PRIVATE.
773  *
774  * \note           Alternative implementations of RSA need not support
775  *                 mode being set to #MBEDTLS_RSA_PUBLIC and might instead
776  *                 return #MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED.
777  *
778  * \param ctx      The initialized RSA context to use.
779  * \param f_rng    The RNG function. If \p mode is #MBEDTLS_RSA_PRIVATE,
780  *                 this is used for blinding and should be provided; see
781  *                 mbedtls_rsa_private() for more. If \p mode is
782  *                 #MBEDTLS_RSA_PUBLIC, it is ignored.
783  * \param p_rng    The RNG context to be passed to \p f_rng. This may be
784  *                 \c NULL if \p f_rng is \c NULL or doesn't need a context.
785  * \param mode     The mode of operation. This must be either
786  *                 #MBEDTLS_RSA_PRIVATE or #MBEDTLS_RSA_PUBLIC (deprecated).
787  * \param olen     The address at which to store the length of
788  *                 the plaintext. This must not be \c NULL.
789  * \param input    The ciphertext buffer. This must be a readable buffer
790  *                 of length \c ctx->len Bytes. For example, \c 256 Bytes
791  *                 for an 2048-bit RSA modulus.
792  * \param output   The buffer used to hold the plaintext. This must
793  *                 be a writable buffer of length \p output_max_len Bytes.
794  * \param output_max_len The length in Bytes of the output buffer \p output.
795  *
796  * \return         \c 0 on success.
797  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
798  *
799  */
800 int mbedtls_rsa_rsaes_pkcs1_v15_decrypt( mbedtls_rsa_context *ctx,
801                                  int (*f_rng)(void *, unsigned char *, size_t),
802                                  void *p_rng,
803                                  int mode, size_t *olen,
804                                  const unsigned char *input,
805                                  unsigned char *output,
806                                  size_t output_max_len );
807 
808 /**
809  * \brief            This function performs a PKCS#1 v2.1 OAEP decryption
810  *                   operation (RSAES-OAEP-DECRYPT).
811  *
812  * \note             The output buffer length \c output_max_len should be
813  *                   as large as the size \p ctx->len of \p ctx->N, for
814  *                   example, 128 Bytes if RSA-1024 is used, to be able to
815  *                   hold an arbitrary decrypted message. If it is not
816  *                   large enough to hold the decryption of the particular
817  *                   ciphertext provided, the function returns
818  *                   #MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE.
819  *
820  * \deprecated       It is deprecated and discouraged to call this function
821  *                   in #MBEDTLS_RSA_PUBLIC mode. Future versions of the library
822  *                   are likely to remove the \p mode argument and have it
823  *                   implicitly set to #MBEDTLS_RSA_PRIVATE.
824  *
825  * \note             Alternative implementations of RSA need not support
826  *                   mode being set to #MBEDTLS_RSA_PUBLIC and might instead
827  *                   return #MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED.
828  *
829  * \param ctx        The initialized RSA context to use.
830  * \param f_rng      The RNG function. If \p mode is #MBEDTLS_RSA_PRIVATE,
831  *                   this is used for blinding and should be provided; see
832  *                   mbedtls_rsa_private() for more. If \p mode is
833  *                   #MBEDTLS_RSA_PUBLIC, it is ignored.
834  * \param p_rng      The RNG context to be passed to \p f_rng. This may be
835  *                   \c NULL if \p f_rng is \c NULL or doesn't need a context.
836  * \param mode       The mode of operation. This must be either
837  *                   #MBEDTLS_RSA_PRIVATE or #MBEDTLS_RSA_PUBLIC (deprecated).
838  * \param label      The buffer holding the custom label to use.
839  *                   This must be a readable buffer of length \p label_len
840  *                   Bytes. It may be \c NULL if \p label_len is \c 0.
841  * \param label_len  The length of the label in Bytes.
842  * \param olen       The address at which to store the length of
843  *                   the plaintext. This must not be \c NULL.
844  * \param input      The ciphertext buffer. This must be a readable buffer
845  *                   of length \c ctx->len Bytes. For example, \c 256 Bytes
846  *                   for an 2048-bit RSA modulus.
847  * \param output     The buffer used to hold the plaintext. This must
848  *                   be a writable buffer of length \p output_max_len Bytes.
849  * \param output_max_len The length in Bytes of the output buffer \p output.
850  *
851  * \return         \c 0 on success.
852  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
853  */
854 int mbedtls_rsa_rsaes_oaep_decrypt( mbedtls_rsa_context *ctx,
855                             int (*f_rng)(void *, unsigned char *, size_t),
856                             void *p_rng,
857                             int mode,
858                             const unsigned char *label, size_t label_len,
859                             size_t *olen,
860                             const unsigned char *input,
861                             unsigned char *output,
862                             size_t output_max_len );
863 
864 /**
865  * \brief          This function performs a private RSA operation to sign
866  *                 a message digest using PKCS#1.
867  *
868  *                 It is the generic wrapper for performing a PKCS#1
869  *                 signature using the \p mode from the context.
870  *
871  * \note           The \p sig buffer must be as large as the size
872  *                 of \p ctx->N. For example, 128 Bytes if RSA-1024 is used.
873  *
874  * \note           For PKCS#1 v2.1 encoding, see comments on
875  *                 mbedtls_rsa_rsassa_pss_sign() for details on
876  *                 \p md_alg and \p hash_id.
877  *
878  * \deprecated     It is deprecated and discouraged to call this function
879  *                 in #MBEDTLS_RSA_PUBLIC mode. Future versions of the library
880  *                 are likely to remove the \p mode argument and have it
881  *                 implicitly set to #MBEDTLS_RSA_PRIVATE.
882  *
883  * \note           Alternative implementations of RSA need not support
884  *                 mode being set to #MBEDTLS_RSA_PUBLIC and might instead
885  *                 return #MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED.
886  *
887  * \param ctx      The initialized RSA context to use.
888  * \param f_rng    The RNG function to use. If the padding mode is PKCS#1 v2.1,
889  *                 this must be provided. If the padding mode is PKCS#1 v1.5 and
890  *                 \p mode is #MBEDTLS_RSA_PRIVATE, it is used for blinding
891  *                 and should be provided; see mbedtls_rsa_private() for more
892  *                 more. It is ignored otherwise.
893  * \param p_rng    The RNG context to be passed to \p f_rng. This may be \c NULL
894  *                 if \p f_rng is \c NULL or doesn't need a context argument.
895  * \param mode     The mode of operation. This must be either
896  *                 #MBEDTLS_RSA_PRIVATE or #MBEDTLS_RSA_PUBLIC (deprecated).
897  * \param md_alg   The message-digest algorithm used to hash the original data.
898  *                 Use #MBEDTLS_MD_NONE for signing raw data.
899  * \param hashlen  The length of the message digest.
900  *                 Ths is only used if \p md_alg is #MBEDTLS_MD_NONE.
901  * \param hash     The buffer holding the message digest or raw data.
902  *                 If \p md_alg is #MBEDTLS_MD_NONE, this must be a readable
903  *                 buffer of length \p hashlen Bytes. If \p md_alg is not
904  *                 #MBEDTLS_MD_NONE, it must be a readable buffer of length
905  *                 the size of the hash corresponding to \p md_alg.
906  * \param sig      The buffer to hold the signature. This must be a writable
907  *                 buffer of length \c ctx->len Bytes. For example, \c 256 Bytes
908  *                 for an 2048-bit RSA modulus. A buffer length of
909  *                 #MBEDTLS_MPI_MAX_SIZE is always safe.
910  *
911  * \return         \c 0 if the signing operation was successful.
912  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
913  */
914 int mbedtls_rsa_pkcs1_sign( mbedtls_rsa_context *ctx,
915                     int (*f_rng)(void *, unsigned char *, size_t),
916                     void *p_rng,
917                     int mode,
918                     mbedtls_md_type_t md_alg,
919                     unsigned int hashlen,
920                     const unsigned char *hash,
921                     unsigned char *sig );
922 
923 /**
924  * \brief          This function performs a PKCS#1 v1.5 signature
925  *                 operation (RSASSA-PKCS1-v1_5-SIGN).
926  *
927  * \deprecated     It is deprecated and discouraged to call this function
928  *                 in #MBEDTLS_RSA_PUBLIC mode. Future versions of the library
929  *                 are likely to remove the \p mode argument and have it
930  *                 implicitly set to #MBEDTLS_RSA_PRIVATE.
931  *
932  * \note           Alternative implementations of RSA need not support
933  *                 mode being set to #MBEDTLS_RSA_PUBLIC and might instead
934  *                 return #MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED.
935  *
936  * \param ctx      The initialized RSA context to use.
937  * \param f_rng    The RNG function. If \p mode is #MBEDTLS_RSA_PRIVATE,
938  *                 this is used for blinding and should be provided; see
939  *                 mbedtls_rsa_private() for more. If \p mode is
940  *                 #MBEDTLS_RSA_PUBLIC, it is ignored.
941  * \param p_rng    The RNG context to be passed to \p f_rng. This may be \c NULL
942  *                 if \p f_rng is \c NULL or doesn't need a context argument.
943  * \param mode     The mode of operation. This must be either
944  *                 #MBEDTLS_RSA_PRIVATE or #MBEDTLS_RSA_PUBLIC (deprecated).
945  * \param md_alg   The message-digest algorithm used to hash the original data.
946  *                 Use #MBEDTLS_MD_NONE for signing raw data.
947  * \param hashlen  The length of the message digest.
948  *                 Ths is only used if \p md_alg is #MBEDTLS_MD_NONE.
949  * \param hash     The buffer holding the message digest or raw data.
950  *                 If \p md_alg is #MBEDTLS_MD_NONE, this must be a readable
951  *                 buffer of length \p hashlen Bytes. If \p md_alg is not
952  *                 #MBEDTLS_MD_NONE, it must be a readable buffer of length
953  *                 the size of the hash corresponding to \p md_alg.
954  * \param sig      The buffer to hold the signature. This must be a writable
955  *                 buffer of length \c ctx->len Bytes. For example, \c 256 Bytes
956  *                 for an 2048-bit RSA modulus. A buffer length of
957  *                 #MBEDTLS_MPI_MAX_SIZE is always safe.
958  *
959  * \return         \c 0 if the signing operation was successful.
960  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
961  */
962 int mbedtls_rsa_rsassa_pkcs1_v15_sign( mbedtls_rsa_context *ctx,
963                                int (*f_rng)(void *, unsigned char *, size_t),
964                                void *p_rng,
965                                int mode,
966                                mbedtls_md_type_t md_alg,
967                                unsigned int hashlen,
968                                const unsigned char *hash,
969                                unsigned char *sig );
970 
971 /**
972  * \brief          This function performs a PKCS#1 v2.1 PSS signature
973  *                 operation (RSASSA-PSS-SIGN).
974  *
975  * \note           The \p hash_id in the RSA context is the one used for the
976  *                 encoding. \p md_alg in the function call is the type of hash
977  *                 that is encoded. According to <em>RFC-3447: Public-Key
978  *                 Cryptography Standards (PKCS) #1 v2.1: RSA Cryptography
979  *                 Specifications</em> it is advised to keep both hashes the
980  *                 same.
981  *
982  * \note           This function always uses the maximum possible salt size,
983  *                 up to the length of the payload hash. This choice of salt
984  *                 size complies with FIPS 186-4 §5.5 (e) and RFC 8017 (PKCS#1
985  *                 v2.2) §9.1.1 step 3. Furthermore this function enforces a
986  *                 minimum salt size which is the hash size minus 2 bytes. If
987  *                 this minimum size is too large given the key size (the salt
988  *                 size, plus the hash size, plus 2 bytes must be no more than
989  *                 the key size in bytes), this function returns
990  *                 #MBEDTLS_ERR_RSA_BAD_INPUT_DATA.
991  *
992  * \deprecated     It is deprecated and discouraged to call this function
993  *                 in #MBEDTLS_RSA_PUBLIC mode. Future versions of the library
994  *                 are likely to remove the \p mode argument and have it
995  *                 implicitly set to #MBEDTLS_RSA_PRIVATE.
996  *
997  * \note           Alternative implementations of RSA need not support
998  *                 mode being set to #MBEDTLS_RSA_PUBLIC and might instead
999  *                 return #MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED.
1000  *
1001  * \param ctx      The initialized RSA context to use.
1002  * \param f_rng    The RNG function. It must not be \c NULL.
1003  * \param p_rng    The RNG context to be passed to \p f_rng. This may be \c NULL
1004  *                 if \p f_rng doesn't need a context argument.
1005  * \param mode     The mode of operation. This must be either
1006  *                 #MBEDTLS_RSA_PRIVATE or #MBEDTLS_RSA_PUBLIC (deprecated).
1007  * \param md_alg   The message-digest algorithm used to hash the original data.
1008  *                 Use #MBEDTLS_MD_NONE for signing raw data.
1009  * \param hashlen  The length of the message digest.
1010  *                 Ths is only used if \p md_alg is #MBEDTLS_MD_NONE.
1011  * \param hash     The buffer holding the message digest or raw data.
1012  *                 If \p md_alg is #MBEDTLS_MD_NONE, this must be a readable
1013  *                 buffer of length \p hashlen Bytes. If \p md_alg is not
1014  *                 #MBEDTLS_MD_NONE, it must be a readable buffer of length
1015  *                 the size of the hash corresponding to \p md_alg.
1016  * \param sig      The buffer to hold the signature. This must be a writable
1017  *                 buffer of length \c ctx->len Bytes. For example, \c 256 Bytes
1018  *                 for an 2048-bit RSA modulus. A buffer length of
1019  *                 #MBEDTLS_MPI_MAX_SIZE is always safe.
1020  *
1021  * \return         \c 0 if the signing operation was successful.
1022  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
1023  */
1024 int mbedtls_rsa_rsassa_pss_sign( mbedtls_rsa_context *ctx,
1025                          int (*f_rng)(void *, unsigned char *, size_t),
1026                          void *p_rng,
1027                          int mode,
1028                          mbedtls_md_type_t md_alg,
1029                          unsigned int hashlen,
1030                          const unsigned char *hash,
1031                          unsigned char *sig );
1032 
1033 /**
1034  * \brief          This function performs a public RSA operation and checks
1035  *                 the message digest.
1036  *
1037  *                 This is the generic wrapper for performing a PKCS#1
1038  *                 verification using the mode from the context.
1039  *
1040  * \note           For PKCS#1 v2.1 encoding, see comments on
1041  *                 mbedtls_rsa_rsassa_pss_verify() about \p md_alg and
1042  *                 \p hash_id.
1043  *
1044  * \deprecated     It is deprecated and discouraged to call this function
1045  *                 in #MBEDTLS_RSA_PRIVATE mode. Future versions of the library
1046  *                 are likely to remove the \p mode argument and have it
1047  *                 set to #MBEDTLS_RSA_PUBLIC.
1048  *
1049  * \note           Alternative implementations of RSA need not support
1050  *                 mode being set to #MBEDTLS_RSA_PRIVATE and might instead
1051  *                 return #MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED.
1052  *
1053  * \param ctx      The initialized RSA public key context to use.
1054  * \param f_rng    The RNG function to use. If \p mode is #MBEDTLS_RSA_PRIVATE,
1055  *                 this is used for blinding and should be provided; see
1056  *                 mbedtls_rsa_private() for more. Otherwise, it is ignored.
1057  * \param p_rng    The RNG context to be passed to \p f_rng. This may be
1058  *                 \c NULL if \p f_rng is \c NULL or doesn't need a context.
1059  * \param mode     The mode of operation. This must be either
1060  *                 #MBEDTLS_RSA_PUBLIC or #MBEDTLS_RSA_PRIVATE (deprecated).
1061  * \param md_alg   The message-digest algorithm used to hash the original data.
1062  *                 Use #MBEDTLS_MD_NONE for signing raw data.
1063  * \param hashlen  The length of the message digest.
1064  *                 This is only used if \p md_alg is #MBEDTLS_MD_NONE.
1065  * \param hash     The buffer holding the message digest or raw data.
1066  *                 If \p md_alg is #MBEDTLS_MD_NONE, this must be a readable
1067  *                 buffer of length \p hashlen Bytes. If \p md_alg is not
1068  *                 #MBEDTLS_MD_NONE, it must be a readable buffer of length
1069  *                 the size of the hash corresponding to \p md_alg.
1070  * \param sig      The buffer holding the signature. This must be a readable
1071  *                 buffer of length \c ctx->len Bytes. For example, \c 256 Bytes
1072  *                 for an 2048-bit RSA modulus.
1073  *
1074  * \return         \c 0 if the verify operation was successful.
1075  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
1076  */
1077 int mbedtls_rsa_pkcs1_verify( mbedtls_rsa_context *ctx,
1078                       int (*f_rng)(void *, unsigned char *, size_t),
1079                       void *p_rng,
1080                       int mode,
1081                       mbedtls_md_type_t md_alg,
1082                       unsigned int hashlen,
1083                       const unsigned char *hash,
1084                       const unsigned char *sig );
1085 
1086 /**
1087  * \brief          This function performs a PKCS#1 v1.5 verification
1088  *                 operation (RSASSA-PKCS1-v1_5-VERIFY).
1089  *
1090  * \deprecated     It is deprecated and discouraged to call this function
1091  *                 in #MBEDTLS_RSA_PRIVATE mode. Future versions of the library
1092  *                 are likely to remove the \p mode argument and have it
1093  *                 set to #MBEDTLS_RSA_PUBLIC.
1094  *
1095  * \note           Alternative implementations of RSA need not support
1096  *                 mode being set to #MBEDTLS_RSA_PRIVATE and might instead
1097  *                 return #MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED.
1098  *
1099  * \param ctx      The initialized RSA public key context to use.
1100  * \param f_rng    The RNG function to use. If \p mode is #MBEDTLS_RSA_PRIVATE,
1101  *                 this is used for blinding and should be provided; see
1102  *                 mbedtls_rsa_private() for more. Otherwise, it is ignored.
1103  * \param p_rng    The RNG context to be passed to \p f_rng. This may be
1104  *                 \c NULL if \p f_rng is \c NULL or doesn't need a context.
1105  * \param mode     The mode of operation. This must be either
1106  *                 #MBEDTLS_RSA_PUBLIC or #MBEDTLS_RSA_PRIVATE (deprecated).
1107  * \param md_alg   The message-digest algorithm used to hash the original data.
1108  *                 Use #MBEDTLS_MD_NONE for signing raw data.
1109  * \param hashlen  The length of the message digest.
1110  *                 This is only used if \p md_alg is #MBEDTLS_MD_NONE.
1111  * \param hash     The buffer holding the message digest or raw data.
1112  *                 If \p md_alg is #MBEDTLS_MD_NONE, this must be a readable
1113  *                 buffer of length \p hashlen Bytes. If \p md_alg is not
1114  *                 #MBEDTLS_MD_NONE, it must be a readable buffer of length
1115  *                 the size of the hash corresponding to \p md_alg.
1116  * \param sig      The buffer holding the signature. This must be a readable
1117  *                 buffer of length \c ctx->len Bytes. For example, \c 256 Bytes
1118  *                 for an 2048-bit RSA modulus.
1119  *
1120  * \return         \c 0 if the verify operation was successful.
1121  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
1122  */
1123 int mbedtls_rsa_rsassa_pkcs1_v15_verify( mbedtls_rsa_context *ctx,
1124                                  int (*f_rng)(void *, unsigned char *, size_t),
1125                                  void *p_rng,
1126                                  int mode,
1127                                  mbedtls_md_type_t md_alg,
1128                                  unsigned int hashlen,
1129                                  const unsigned char *hash,
1130                                  const unsigned char *sig );
1131 
1132 /**
1133  * \brief          This function performs a PKCS#1 v2.1 PSS verification
1134  *                 operation (RSASSA-PSS-VERIFY).
1135  *
1136  *                 The hash function for the MGF mask generating function
1137  *                 is that specified in the RSA context.
1138  *
1139  * \note           The \p hash_id in the RSA context is the one used for the
1140  *                 verification. \p md_alg in the function call is the type of
1141  *                 hash that is verified. According to <em>RFC-3447: Public-Key
1142  *                 Cryptography Standards (PKCS) #1 v2.1: RSA Cryptography
1143  *                 Specifications</em> it is advised to keep both hashes the
1144  *                 same. If \p hash_id in the RSA context is unset,
1145  *                 the \p md_alg from the function call is used.
1146  *
1147  * \deprecated     It is deprecated and discouraged to call this function
1148  *                 in #MBEDTLS_RSA_PRIVATE mode. Future versions of the library
1149  *                 are likely to remove the \p mode argument and have it
1150  *                 implicitly set to #MBEDTLS_RSA_PUBLIC.
1151  *
1152  * \note           Alternative implementations of RSA need not support
1153  *                 mode being set to #MBEDTLS_RSA_PRIVATE and might instead
1154  *                 return #MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED.
1155  *
1156  * \param ctx      The initialized RSA public key context to use.
1157  * \param f_rng    The RNG function to use. If \p mode is #MBEDTLS_RSA_PRIVATE,
1158  *                 this is used for blinding and should be provided; see
1159  *                 mbedtls_rsa_private() for more. Otherwise, it is ignored.
1160  * \param p_rng    The RNG context to be passed to \p f_rng. This may be
1161  *                 \c NULL if \p f_rng is \c NULL or doesn't need a context.
1162  * \param mode     The mode of operation. This must be either
1163  *                 #MBEDTLS_RSA_PUBLIC or #MBEDTLS_RSA_PRIVATE (deprecated).
1164  * \param md_alg   The message-digest algorithm used to hash the original data.
1165  *                 Use #MBEDTLS_MD_NONE for signing raw data.
1166  * \param hashlen  The length of the message digest.
1167  *                 This is only used if \p md_alg is #MBEDTLS_MD_NONE.
1168  * \param hash     The buffer holding the message digest or raw data.
1169  *                 If \p md_alg is #MBEDTLS_MD_NONE, this must be a readable
1170  *                 buffer of length \p hashlen Bytes. If \p md_alg is not
1171  *                 #MBEDTLS_MD_NONE, it must be a readable buffer of length
1172  *                 the size of the hash corresponding to \p md_alg.
1173  * \param sig      The buffer holding the signature. This must be a readable
1174  *                 buffer of length \c ctx->len Bytes. For example, \c 256 Bytes
1175  *                 for an 2048-bit RSA modulus.
1176  *
1177  * \return         \c 0 if the verify operation was successful.
1178  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
1179  */
1180 int mbedtls_rsa_rsassa_pss_verify( mbedtls_rsa_context *ctx,
1181                            int (*f_rng)(void *, unsigned char *, size_t),
1182                            void *p_rng,
1183                            int mode,
1184                            mbedtls_md_type_t md_alg,
1185                            unsigned int hashlen,
1186                            const unsigned char *hash,
1187                            const unsigned char *sig );
1188 
1189 /**
1190  * \brief          This function performs a PKCS#1 v2.1 PSS verification
1191  *                 operation (RSASSA-PSS-VERIFY).
1192  *
1193  *                 The hash function for the MGF mask generating function
1194  *                 is that specified in \p mgf1_hash_id.
1195  *
1196  * \note           The \p sig buffer must be as large as the size
1197  *                 of \p ctx->N. For example, 128 Bytes if RSA-1024 is used.
1198  *
1199  * \note           The \p hash_id in the RSA context is ignored.
1200  *
1201  * \param ctx      The initialized RSA public key context to use.
1202  * \param f_rng    The RNG function to use. If \p mode is #MBEDTLS_RSA_PRIVATE,
1203  *                 this is used for blinding and should be provided; see
1204  *                 mbedtls_rsa_private() for more. Otherwise, it is ignored.
1205  * \param p_rng    The RNG context to be passed to \p f_rng. This may be
1206  *                 \c NULL if \p f_rng is \c NULL or doesn't need a context.
1207  * \param mode     The mode of operation. This must be either
1208  *                 #MBEDTLS_RSA_PUBLIC or #MBEDTLS_RSA_PRIVATE.
1209  * \param md_alg   The message-digest algorithm used to hash the original data.
1210  *                 Use #MBEDTLS_MD_NONE for signing raw data.
1211  * \param hashlen  The length of the message digest.
1212  *                 This is only used if \p md_alg is #MBEDTLS_MD_NONE.
1213  * \param hash     The buffer holding the message digest or raw data.
1214  *                 If \p md_alg is #MBEDTLS_MD_NONE, this must be a readable
1215  *                 buffer of length \p hashlen Bytes. If \p md_alg is not
1216  *                 #MBEDTLS_MD_NONE, it must be a readable buffer of length
1217  *                 the size of the hash corresponding to \p md_alg.
1218  * \param mgf1_hash_id      The message digest used for mask generation.
1219  * \param expected_salt_len The length of the salt used in padding. Use
1220  *                          #MBEDTLS_RSA_SALT_LEN_ANY to accept any salt length.
1221  * \param sig      The buffer holding the signature. This must be a readable
1222  *                 buffer of length \c ctx->len Bytes. For example, \c 256 Bytes
1223  *                 for an 2048-bit RSA modulus.
1224  *
1225  * \return         \c 0 if the verify operation was successful.
1226  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
1227  */
1228 int mbedtls_rsa_rsassa_pss_verify_ext( mbedtls_rsa_context *ctx,
1229                                int (*f_rng)(void *, unsigned char *, size_t),
1230                                void *p_rng,
1231                                int mode,
1232                                mbedtls_md_type_t md_alg,
1233                                unsigned int hashlen,
1234                                const unsigned char *hash,
1235                                mbedtls_md_type_t mgf1_hash_id,
1236                                int expected_salt_len,
1237                                const unsigned char *sig );
1238 
1239 /**
1240  * \brief          This function copies the components of an RSA context.
1241  *
1242  * \param dst      The destination context. This must be initialized.
1243  * \param src      The source context. This must be initialized.
1244  *
1245  * \return         \c 0 on success.
1246  * \return         #MBEDTLS_ERR_MPI_ALLOC_FAILED on memory allocation failure.
1247  */
1248 int mbedtls_rsa_copy( mbedtls_rsa_context *dst, const mbedtls_rsa_context *src );
1249 
1250 /**
1251  * \brief          This function frees the components of an RSA key.
1252  *
1253  * \param ctx      The RSA context to free. May be \c NULL, in which case
1254  *                 this function is a no-op. If it is not \c NULL, it must
1255  *                 point to an initialized RSA context.
1256  */
1257 void mbedtls_rsa_free( mbedtls_rsa_context *ctx );
1258 
1259 #if defined(MBEDTLS_SELF_TEST)
1260 
1261 /**
1262  * \brief          The RSA checkup routine.
1263  *
1264  * \return         \c 0 on success.
1265  * \return         \c 1 on failure.
1266  */
1267 int mbedtls_rsa_self_test( int verbose );
1268 
1269 #endif /* MBEDTLS_SELF_TEST */
1270 
1271 #ifdef __cplusplus
1272 }
1273 #endif
1274 
1275 #endif /* rsa.h */
1276