[proxmark3-svn] / common / mbedtls / ctr_drbg.h

/**
 * \file ctr_drbg.h
 *
 * \brief    This file contains CTR_DRBG definitions and functions.
 *
 * CTR_DRBG is a standardized way of building a PRNG from a block-cipher
 * in counter mode operation, as defined in <em>NIST SP 800-90A:
 * Recommendation for Random Number Generation Using Deterministic Random
 * Bit Generators</em>.
 *
 * The Mbed TLS implementation of CTR_DRBG uses AES-256 as the underlying
 * block cipher.
 */
/*
 *  Copyright (C) 2006-2018, Arm Limited (or its affiliates), All Rights Reserved
 *  SPDX-License-Identifier: GPL-2.0
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 *  This file is part of Mbed TLS (https://tls.mbed.org)
 */

#ifndef MBEDTLS_CTR_DRBG_H
#define MBEDTLS_CTR_DRBG_H

#include "aes.h"

#if defined(MBEDTLS_THREADING_C)
#include "threading.h"
#endif

#define MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED        -0x0034  /**< The entropy source failed. */
#define MBEDTLS_ERR_CTR_DRBG_REQUEST_TOO_BIG              -0x0036  /**< The requested random buffer length is too big. */
#define MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG                -0x0038  /**< The input (entropy + additional data) is too large. */
#define MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR                -0x003A  /**< Read or write error in file. */

#define MBEDTLS_CTR_DRBG_BLOCKSIZE          16 /**< The block size used by the cipher. */
#define MBEDTLS_CTR_DRBG_KEYSIZE            32 /**< The key size used by the cipher. */
#define MBEDTLS_CTR_DRBG_KEYBITS            ( MBEDTLS_CTR_DRBG_KEYSIZE * 8 ) /**< The key size for the DRBG operation, in bits. */
#define MBEDTLS_CTR_DRBG_SEEDLEN            ( MBEDTLS_CTR_DRBG_KEYSIZE + MBEDTLS_CTR_DRBG_BLOCKSIZE ) /**< The seed length, calculated as (counter + AES key). */

/**
 * \name SECTION: Module settings
 *
 * The configuration options you can set for this module are in this section.
 * Either change them in config.h or define them using the compiler command
 * line.
 * \{
 */

#if !defined(MBEDTLS_CTR_DRBG_ENTROPY_LEN)
#if defined(MBEDTLS_SHA512_C) && !defined(MBEDTLS_ENTROPY_FORCE_SHA256)
#define MBEDTLS_CTR_DRBG_ENTROPY_LEN        48
/**< The amount of entropy used per seed by default:
 * <ul><li>48 with SHA-512.</li>
 * <li>32 with SHA-256.</li></ul>
 */
#else
#define MBEDTLS_CTR_DRBG_ENTROPY_LEN        32
/**< Amount of entropy used per seed by default:
 * <ul><li>48 with SHA-512.</li>
 * <li>32 with SHA-256.</li></ul>
 */
#endif
#endif

#if !defined(MBEDTLS_CTR_DRBG_RESEED_INTERVAL)
#define MBEDTLS_CTR_DRBG_RESEED_INTERVAL    10000
/**< The interval before reseed is performed by default. */
#endif

#if !defined(MBEDTLS_CTR_DRBG_MAX_INPUT)
#define MBEDTLS_CTR_DRBG_MAX_INPUT          256
/**< The maximum number of additional input Bytes. */
#endif

#if !defined(MBEDTLS_CTR_DRBG_MAX_REQUEST)
#define MBEDTLS_CTR_DRBG_MAX_REQUEST        1024
/**< The maximum number of requested Bytes per call. */
#endif

#if !defined(MBEDTLS_CTR_DRBG_MAX_SEED_INPUT)
#define MBEDTLS_CTR_DRBG_MAX_SEED_INPUT     384
/**< The maximum size of seed or reseed buffer. */
#endif

/* \} name SECTION: Module settings */

#define MBEDTLS_CTR_DRBG_PR_OFF             0
/**< Prediction resistance is disabled. */
#define MBEDTLS_CTR_DRBG_PR_ON              1
/**< Prediction resistance is enabled. */

#ifdef __cplusplus
extern "C" {
#endif

/**
 * \brief          The CTR_DRBG context structure.
 */
typedef struct mbedtls_ctr_drbg_context
{
    unsigned char counter[16];  /*!< The counter (V). */
    int reseed_counter;         /*!< The reseed counter. */
    int prediction_resistance;  /*!< This determines whether prediction
                                     resistance is enabled, that is
                                     whether to systematically reseed before
                                     each random generation. */
    size_t entropy_len;         /*!< The amount of entropy grabbed on each
                                     seed or reseed operation. */
    int reseed_interval;        /*!< The reseed interval. */

    mbedtls_aes_context aes_ctx;        /*!< The AES context. */

    /*
     * Callbacks (Entropy)
     */
    int (*f_entropy)(void *, unsigned char *, size_t);
                                /*!< The entropy callback function. */

    void *p_entropy;            /*!< The context for the entropy function. */

#if defined(MBEDTLS_THREADING_C)
    mbedtls_threading_mutex_t mutex;
#endif
}
mbedtls_ctr_drbg_context;

/**
 * \brief               This function initializes the CTR_DRBG context,
 *                      and prepares it for mbedtls_ctr_drbg_seed()
 *                      or mbedtls_ctr_drbg_free().
 *
 * \param ctx           The CTR_DRBG context to initialize.
 */
void mbedtls_ctr_drbg_init( mbedtls_ctr_drbg_context *ctx );

/**
 * \brief               This function seeds and sets up the CTR_DRBG
 *                      entropy source for future reseeds.
 *
 * \note Personalization data can be provided in addition to the more generic
 *       entropy source, to make this instantiation as unique as possible.
 *
 * \param ctx           The CTR_DRBG context to seed.
 * \param f_entropy     The entropy callback, taking as arguments the
 *                      \p p_entropy context, the buffer to fill, and the
                        length of the buffer.
 * \param p_entropy     The entropy context.
 * \param custom        Personalization data, that is device-specific
                        identifiers. Can be NULL.
 * \param len           The length of the personalization data.
 *
 * \return              \c 0 on success.
 * \return              #MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED on failure.
 */
int mbedtls_ctr_drbg_seed( mbedtls_ctr_drbg_context *ctx,
                   int (*f_entropy)(void *, unsigned char *, size_t),
                   void *p_entropy,
                   const unsigned char *custom,
                   size_t len );

/**
 * \brief               This function clears CTR_CRBG context data.
 *
 * \param ctx           The CTR_DRBG context to clear.
 */
void mbedtls_ctr_drbg_free( mbedtls_ctr_drbg_context *ctx );

/**
 * \brief               This function turns prediction resistance on or off.
 *                      The default value is off.
 *
 * \note                If enabled, entropy is gathered at the beginning of
 *                      every call to mbedtls_ctr_drbg_random_with_add().
 *                      Only use this if your entropy source has sufficient
 *                      throughput.
 *
 * \param ctx           The CTR_DRBG context.
 * \param resistance    #MBEDTLS_CTR_DRBG_PR_ON or #MBEDTLS_CTR_DRBG_PR_OFF.
 */
void mbedtls_ctr_drbg_set_prediction_resistance( mbedtls_ctr_drbg_context *ctx,
                                         int resistance );

/**
 * \brief               This function sets the amount of entropy grabbed on each
 *                      seed or reseed. The default value is
 *                      #MBEDTLS_CTR_DRBG_ENTROPY_LEN.
 *
 * \param ctx           The CTR_DRBG context.
 * \param len           The amount of entropy to grab.
 */
void mbedtls_ctr_drbg_set_entropy_len( mbedtls_ctr_drbg_context *ctx,
                               size_t len );

/**
 * \brief               This function sets the reseed interval.
 *                      The default value is #MBEDTLS_CTR_DRBG_RESEED_INTERVAL.
 *
 * \param ctx           The CTR_DRBG context.
 * \param interval      The reseed interval.
 */
void mbedtls_ctr_drbg_set_reseed_interval( mbedtls_ctr_drbg_context *ctx,
                                   int interval );

/**
 * \brief               This function reseeds the CTR_DRBG context, that is
 *                      extracts data from the entropy source.
 *
 * \param ctx           The CTR_DRBG context.
 * \param additional    Additional data to add to the state. Can be NULL.
 * \param len           The length of the additional data.
 *
 * \return              \c 0 on success.
 * \return              #MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED on failure.
 */
int mbedtls_ctr_drbg_reseed( mbedtls_ctr_drbg_context *ctx,
                     const unsigned char *additional, size_t len );

/**
 * \brief              This function updates the state of the CTR_DRBG context.
 *
 * \note               If \p add_len is greater than
 *                     #MBEDTLS_CTR_DRBG_MAX_SEED_INPUT, only the first
 *                     #MBEDTLS_CTR_DRBG_MAX_SEED_INPUT Bytes are used.
 *                     The remaining Bytes are silently discarded.
 *
 * \param ctx          The CTR_DRBG context.
 * \param additional   The data to update the state with.
 * \param add_len      Length of \p additional data.
 *
 */
void mbedtls_ctr_drbg_update( mbedtls_ctr_drbg_context *ctx,
                      const unsigned char *additional, size_t add_len );

/**
 * \brief   This function updates a CTR_DRBG instance with additional
 *          data and uses it to generate random data.
 *
 * \note    The function automatically reseeds if the reseed counter is exceeded.
 *
 * \param p_rng         The CTR_DRBG context. This must be a pointer to a
 *                      #mbedtls_ctr_drbg_context structure.
 * \param output        The buffer to fill.
 * \param output_len    The length of the buffer.
 * \param additional    Additional data to update. Can be NULL.
 * \param add_len       The length of the additional data.
 *
 * \return    \c 0 on success.
 * \return    #MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED or
 *            #MBEDTLS_ERR_CTR_DRBG_REQUEST_TOO_BIG on failure.
 */
int mbedtls_ctr_drbg_random_with_add( void *p_rng,
                              unsigned char *output, size_t output_len,
                              const unsigned char *additional, size_t add_len );

/**
 * \brief   This function uses CTR_DRBG to generate random data.
 *
 * \note    The function automatically reseeds if the reseed counter is exceeded.
 *
 * \param p_rng         The CTR_DRBG context. This must be a pointer to a
 *                      #mbedtls_ctr_drbg_context structure.
 * \param output        The buffer to fill.
 * \param output_len    The length of the buffer.
 *
 * \return              \c 0 on success.
 * \return              #MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED or
 *                      #MBEDTLS_ERR_CTR_DRBG_REQUEST_TOO_BIG on failure.
 */
int mbedtls_ctr_drbg_random( void *p_rng,
                     unsigned char *output, size_t output_len );

#if defined(MBEDTLS_FS_IO)
/**
 * \brief               This function writes a seed file.
 *
 * \param ctx           The CTR_DRBG context.
 * \param path          The name of the file.
 *
 * \return              \c 0 on success.
 * \return              #MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR on file error.
 * \return              #MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED on
 *                      failure.
 */
int mbedtls_ctr_drbg_write_seed_file( mbedtls_ctr_drbg_context *ctx, const char *path );

/**
 * \brief               This function reads and updates a seed file. The seed
 *                      is added to this instance.
 *
 * \param ctx           The CTR_DRBG context.
 * \param path          The name of the file.
 *
 * \return              \c 0 on success.
 * \return              #MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR on file error.
 * \return              #MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED or
 *                      #MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG on failure.
 */
int mbedtls_ctr_drbg_update_seed_file( mbedtls_ctr_drbg_context *ctx, const char *path );
#endif /* MBEDTLS_FS_IO */

/**
 * \brief               The CTR_DRBG checkup routine.
 *
 * \return              \c 0 on success.
 * \return              \c 1 on failure.
 */
int mbedtls_ctr_drbg_self_test( int verbose );

/* Internal functions (do not call directly) */
int mbedtls_ctr_drbg_seed_entropy_len( mbedtls_ctr_drbg_context *,
                               int (*)(void *, unsigned char *, size_t), void *,
                               const unsigned char *, size_t, size_t );

#ifdef __cplusplus
}
#endif

#endif /* ctr_drbg.h */
Commit	Line	Data
700d8687 OM	1	/**
	2	* \file ctr_drbg.h
	3	*
	4	* \brief This file contains CTR_DRBG definitions and functions.
	5	*
	6	* CTR_DRBG is a standardized way of building a PRNG from a block-cipher
	7	* in counter mode operation, as defined in <em>NIST SP 800-90A:
	8	* Recommendation for Random Number Generation Using Deterministic Random
	9	* Bit Generators</em>.
	10	*
	11	* The Mbed TLS implementation of CTR_DRBG uses AES-256 as the underlying
	12	* block cipher.
	13	*/
	14	/*
	15	* Copyright (C) 2006-2018, Arm Limited (or its affiliates), All Rights Reserved
	16	* SPDX-License-Identifier: GPL-2.0
	17	*
	18	* This program is free software; you can redistribute it and/or modify
	19	* it under the terms of the GNU General Public License as published by
	20	* the Free Software Foundation; either version 2 of the License, or
	21	* (at your option) any later version.
	22	*
	23	* This program is distributed in the hope that it will be useful,
	24	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	25	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	26	* GNU General Public License for more details.
	27	*
	28	* You should have received a copy of the GNU General Public License along
	29	* with this program; if not, write to the Free Software Foundation, Inc.,
	30	* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
	31	*
	32	* This file is part of Mbed TLS (https://tls.mbed.org)
	33	*/
	34
	35	#ifndef MBEDTLS_CTR_DRBG_H
	36	#define MBEDTLS_CTR_DRBG_H
	37
	38	#include "aes.h"
	39
	40	#if defined(MBEDTLS_THREADING_C)
	41	#include "threading.h"
	42	#endif
	43
	44	#define MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED -0x0034 /*< The entropy source failed. /
	45	#define MBEDTLS_ERR_CTR_DRBG_REQUEST_TOO_BIG -0x0036 /*< The requested random buffer length is too big. /
	46	#define MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG -0x0038 /*< The input (entropy + additional data) is too large. /
	47	#define MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR -0x003A /*< Read or write error in file. /
	48
	49	#define MBEDTLS_CTR_DRBG_BLOCKSIZE 16 /*< The block size used by the cipher. /
	50	#define MBEDTLS_CTR_DRBG_KEYSIZE 32 /*< The key size used by the cipher. /
	51	#define MBEDTLS_CTR_DRBG_KEYBITS ( MBEDTLS_CTR_DRBG_KEYSIZE * 8 ) /*< The key size for the DRBG operation, in bits. /
	52	#define MBEDTLS_CTR_DRBG_SEEDLEN ( MBEDTLS_CTR_DRBG_KEYSIZE + MBEDTLS_CTR_DRBG_BLOCKSIZE ) /*< The seed length, calculated as (counter + AES key). /
	53
	54	/**
	55	* \name SECTION: Module settings
	56	*
	57	* The configuration options you can set for this module are in this section.
	58	* Either change them in config.h or define them using the compiler command
	59	* line.
	60	* \{
	61	*/
	62
	63	#if !defined(MBEDTLS_CTR_DRBG_ENTROPY_LEN)
	64	#if defined(MBEDTLS_SHA512_C) && !defined(MBEDTLS_ENTROPY_FORCE_SHA256)
65	#define MBEDTLS_CTR_DRBG_ENTROPY_LEN 48
66	/**< The amount of entropy used per seed by default:
67	* <ul><li>48 with SHA-512.</li>
68	* <li>32 with SHA-256.</li></ul>
69	*/
70	#else
71	#define MBEDTLS_CTR_DRBG_ENTROPY_LEN 32
72	/**< Amount of entropy used per seed by default:
73	* <ul><li>48 with SHA-512.</li>
74	* <li>32 with SHA-256.</li></ul>
75	*/
76	#endif
77	#endif
78
79	#if !defined(MBEDTLS_CTR_DRBG_RESEED_INTERVAL)
80	#define MBEDTLS_CTR_DRBG_RESEED_INTERVAL 10000
81	/*< The interval before reseed is performed by default. /
82	#endif
83
84	#if !defined(MBEDTLS_CTR_DRBG_MAX_INPUT)
85	#define MBEDTLS_CTR_DRBG_MAX_INPUT 256
86	/*< The maximum number of additional input Bytes. /
87	#endif
88
89	#if !defined(MBEDTLS_CTR_DRBG_MAX_REQUEST)
90	#define MBEDTLS_CTR_DRBG_MAX_REQUEST 1024
91	/*< The maximum number of requested Bytes per call. /
92	#endif
93
94	#if !defined(MBEDTLS_CTR_DRBG_MAX_SEED_INPUT)
95	#define MBEDTLS_CTR_DRBG_MAX_SEED_INPUT 384
96	/*< The maximum size of seed or reseed buffer. /
97	#endif
98
99	/* \} name SECTION: Module settings */
100
101	#define MBEDTLS_CTR_DRBG_PR_OFF 0
102	/*< Prediction resistance is disabled. /
103	#define MBEDTLS_CTR_DRBG_PR_ON 1
104	/*< Prediction resistance is enabled. /
105
106	#ifdef __cplusplus
107	extern "C" {
108	#endif
109
110	/**
111	* \brief The CTR_DRBG context structure.
112	*/
113	typedef struct mbedtls_ctr_drbg_context
114	{
115	unsigned char counter[16]; /!< The counter (V). /
116	int reseed_counter; /!< The reseed counter. /
117	int prediction_resistance; /*!< This determines whether prediction
118	resistance is enabled, that is
119	whether to systematically reseed before
120	each random generation. */
121	size_t entropy_len; /*!< The amount of entropy grabbed on each
122	seed or reseed operation. */
123	int reseed_interval; /!< The reseed interval. /
124
125	mbedtls_aes_context aes_ctx; /!< The AES context. /
126
127	/*
128	* Callbacks (Entropy)
129	*/
130	int (f_entropy)(void , unsigned char *, size_t);
131	/!< The entropy callback function. /
132
133	void p_entropy; /!< The context for the entropy function. */
134
135	#if defined(MBEDTLS_THREADING_C)
136	mbedtls_threading_mutex_t mutex;
137	#endif
138	}
139	mbedtls_ctr_drbg_context;
140
141	/**
142	* \brief This function initializes the CTR_DRBG context,
143	* and prepares it for mbedtls_ctr_drbg_seed()
144	* or mbedtls_ctr_drbg_free().
145	*
146	* \param ctx The CTR_DRBG context to initialize.
147	*/
148	void mbedtls_ctr_drbg_init( mbedtls_ctr_drbg_context *ctx );
149
150	/**
151	* \brief This function seeds and sets up the CTR_DRBG
152	* entropy source for future reseeds.
153	*
154	* \note Personalization data can be provided in addition to the more generic
155	* entropy source, to make this instantiation as unique as possible.
156	*
157	* \param ctx The CTR_DRBG context to seed.
158	* \param f_entropy The entropy callback, taking as arguments the
159	* \p p_entropy context, the buffer to fill, and the
160	length of the buffer.
161	* \param p_entropy The entropy context.
162	* \param custom Personalization data, that is device-specific
163	identifiers. Can be NULL.
164	* \param len The length of the personalization data.
165	*
166	* \return \c 0 on success.
167	* \return #MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED on failure.
168	*/
169	int mbedtls_ctr_drbg_seed( mbedtls_ctr_drbg_context *ctx,
170	int (f_entropy)(void , unsigned char *, size_t),
171	void *p_entropy,
172	const unsigned char *custom,
173	size_t len );
174
175	/**
176	* \brief This function clears CTR_CRBG context data.
177	*
178	* \param ctx The CTR_DRBG context to clear.
179	*/
180	void mbedtls_ctr_drbg_free( mbedtls_ctr_drbg_context *ctx );
181
182	/**
183	* \brief This function turns prediction resistance on or off.
184	* The default value is off.
185	*
186	* \note If enabled, entropy is gathered at the beginning of
187	* every call to mbedtls_ctr_drbg_random_with_add().
188	* Only use this if your entropy source has sufficient
189	* throughput.
190	*
191	* \param ctx The CTR_DRBG context.
192	* \param resistance #MBEDTLS_CTR_DRBG_PR_ON or #MBEDTLS_CTR_DRBG_PR_OFF.
193	*/
194	void mbedtls_ctr_drbg_set_prediction_resistance( mbedtls_ctr_drbg_context *ctx,
195	int resistance );
196
197	/**
198	* \brief This function sets the amount of entropy grabbed on each
199	* seed or reseed. The default value is
200	* #MBEDTLS_CTR_DRBG_ENTROPY_LEN.
201	*
202	* \param ctx The CTR_DRBG context.
203	* \param len The amount of entropy to grab.
204	*/
205	void mbedtls_ctr_drbg_set_entropy_len( mbedtls_ctr_drbg_context *ctx,
206	size_t len );
207
208	/**
209	* \brief This function sets the reseed interval.
210	* The default value is #MBEDTLS_CTR_DRBG_RESEED_INTERVAL.
211	*
212	* \param ctx The CTR_DRBG context.
213	* \param interval The reseed interval.
214	*/
215	void mbedtls_ctr_drbg_set_reseed_interval( mbedtls_ctr_drbg_context *ctx,
216	int interval );
217
218	/**
219	* \brief This function reseeds the CTR_DRBG context, that is
220	* extracts data from the entropy source.
221	*
222	* \param ctx The CTR_DRBG context.
223	* \param additional Additional data to add to the state. Can be NULL.
224	* \param len The length of the additional data.
225	*
226	* \return \c 0 on success.
227	* \return #MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED on failure.
228	*/
229	int mbedtls_ctr_drbg_reseed( mbedtls_ctr_drbg_context *ctx,
230	const unsigned char *additional, size_t len );
231
232	/**
233	* \brief This function updates the state of the CTR_DRBG context.
234	*
235	* \note If \p add_len is greater than
236	* #MBEDTLS_CTR_DRBG_MAX_SEED_INPUT, only the first
237	* #MBEDTLS_CTR_DRBG_MAX_SEED_INPUT Bytes are used.
238	* The remaining Bytes are silently discarded.
239	*
240	* \param ctx The CTR_DRBG context.
241	* \param additional The data to update the state with.
242	* \param add_len Length of \p additional data.
243	*
244	*/
245	void mbedtls_ctr_drbg_update( mbedtls_ctr_drbg_context *ctx,
246	const unsigned char *additional, size_t add_len );
247
248	/**
249	* \brief This function updates a CTR_DRBG instance with additional
250	* data and uses it to generate random data.
251	*
252	* \note The function automatically reseeds if the reseed counter is exceeded.
253	*
254	* \param p_rng The CTR_DRBG context. This must be a pointer to a
255	* #mbedtls_ctr_drbg_context structure.
256	* \param output The buffer to fill.
257	* \param output_len The length of the buffer.
258	* \param additional Additional data to update. Can be NULL.
259	* \param add_len The length of the additional data.
260	*
261	* \return \c 0 on success.
262	* \return #MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED or
263	* #MBEDTLS_ERR_CTR_DRBG_REQUEST_TOO_BIG on failure.
264	*/
265	int mbedtls_ctr_drbg_random_with_add( void *p_rng,
266	unsigned char *output, size_t output_len,
267	const unsigned char *additional, size_t add_len );
268
269	/**
270	* \brief This function uses CTR_DRBG to generate random data.
271	*
272	* \note The function automatically reseeds if the reseed counter is exceeded.
273	*
274	* \param p_rng The CTR_DRBG context. This must be a pointer to a
275	* #mbedtls_ctr_drbg_context structure.
276	* \param output The buffer to fill.
277	* \param output_len The length of the buffer.
278	*
279	* \return \c 0 on success.
280	* \return #MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED or
281	* #MBEDTLS_ERR_CTR_DRBG_REQUEST_TOO_BIG on failure.
282	*/
283	int mbedtls_ctr_drbg_random( void *p_rng,
284	unsigned char *output, size_t output_len );
285
286	#if defined(MBEDTLS_FS_IO)
287	/**
288	* \brief This function writes a seed file.
289	*
290	* \param ctx The CTR_DRBG context.
291	* \param path The name of the file.
292	*
293	* \return \c 0 on success.
294	* \return #MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR on file error.
295	* \return #MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED on
296	* failure.
297	*/
298	int mbedtls_ctr_drbg_write_seed_file( mbedtls_ctr_drbg_context ctx, const char path );
299
300	/**
301	* \brief This function reads and updates a seed file. The seed
302	* is added to this instance.
303	*
304	* \param ctx The CTR_DRBG context.
305	* \param path The name of the file.
306	*
307	* \return \c 0 on success.
308	* \return #MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR on file error.
309	* \return #MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED or
310	* #MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG on failure.
311	*/
312	int mbedtls_ctr_drbg_update_seed_file( mbedtls_ctr_drbg_context ctx, const char path );
313	#endif /* MBEDTLS_FS_IO */
314
315	/**
316	* \brief The CTR_DRBG checkup routine.
317	*
318	* \return \c 0 on success.
319	* \return \c 1 on failure.
320	*/
321	int mbedtls_ctr_drbg_self_test( int verbose );
322
323	/* Internal functions (do not call directly) */
324	int mbedtls_ctr_drbg_seed_entropy_len( mbedtls_ctr_drbg_context *,
325	int ()(void , unsigned char , size_t), void ,
326	const unsigned char *, size_t, size_t );
327
328	#ifdef __cplusplus
329	}
330	#endif
331
332	#endif /* ctr_drbg.h */