CTR_DRBG is based on AES-256, as defined in NIST SP 800-90A: Recommendation for Random Number Generation Using Deterministic Random Bit Generators. More...

Data Structures
struct	mbedtls_ctr_drbg_context
	The CTR_DRBG context structure. More...
Functions
void	mbedtls_ctr_drbg_init (mbedtls_ctr_drbg_context *ctx)
	This function initializes the CTR_DRBG context, and prepares it for mbedtls_ctr_drbg_seed() or mbedtls_ctr_drbg_free().
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)
	This function seeds and sets up the CTR_DRBG entropy source for future reseeds.
void	mbedtls_ctr_drbg_free (mbedtls_ctr_drbg_context *ctx)
	This function clears CTR_CRBG context data.
void	mbedtls_ctr_drbg_set_prediction_resistance (mbedtls_ctr_drbg_context *ctx, int resistance)
	This function turns prediction resistance on or off.
void	mbedtls_ctr_drbg_set_entropy_len (mbedtls_ctr_drbg_context *ctx, size_t len)
	This function sets the amount of entropy grabbed on each seed or reseed.
void	mbedtls_ctr_drbg_set_reseed_interval (mbedtls_ctr_drbg_context *ctx, int interval)
	This function sets the reseed interval.
int	mbedtls_ctr_drbg_reseed (mbedtls_ctr_drbg_context ctx, const unsigned char additional, size_t len)
	This function reseeds the CTR_DRBG context, that is extracts data from the entropy source.
void	mbedtls_ctr_drbg_update (mbedtls_ctr_drbg_context ctx, const unsigned char additional, size_t add_len)
	This function updates the state of the CTR_DRBG context.
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)
	This function updates a CTR_DRBG instance with additional data and uses it to generate random data.
int	mbedtls_ctr_drbg_random (void p_rng, unsigned char output, size_t output_len)
	This function uses CTR_DRBG to generate random data.
int	mbedtls_ctr_drbg_write_seed_file (mbedtls_ctr_drbg_context ctx, const char path)
	This function writes a seed file.
int	mbedtls_ctr_drbg_update_seed_file (mbedtls_ctr_drbg_context ctx, const char path)
	This function reads and updates a seed file.
int	mbedtls_ctr_drbg_self_test (int verbose)
	The CTR_DRBG checkup routine.

Detailed Description

CTR_DRBG is based on AES-256, as defined in NIST SP 800-90A: Recommendation for Random Number Generation Using Deterministic Random Bit Generators.

Definition in file ctr_drbg.h.

Function Documentation

void mbedtls_ctr_drbg_free ( mbedtls_ctr_drbg_context * ctx )

This function clears CTR_CRBG context data.

Parameters:

ctx	The CTR_DRBG context to clear.

Definition at line 119 of file ctr_drbg.c.

void mbedtls_ctr_drbg_init ( mbedtls_ctr_drbg_context * ctx )

This function initializes the CTR_DRBG context, and prepares it for mbedtls_ctr_drbg_seed() or mbedtls_ctr_drbg_free().

Parameters:

ctx	The CTR_DRBG context to initialize.

Definition at line 60 of file ctr_drbg.c.

int mbedtls_ctr_drbg_random	(	void *	p_rng,
		unsigned char *	output,
		size_t	output_len
	)

This function uses CTR_DRBG to generate random data.

Note:: The function automatically reseeds if the reseed counter is exceeded.

Parameters:

p_rng	The CTR_DRBG context. This must be a pointer to a mbedtls_ctr_drbg_context structure.
output	The buffer to fill.
output_len	The length of the buffer.

Returns:: 0 on success, or MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED or MBEDTLS_ERR_CTR_DRBG_REQUEST_TOO_BIG on failure.

Definition at line 457 of file ctr_drbg.c.

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
	)

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.

Parameters:

p_rng	The CTR_DRBG context. This must be a pointer to a mbedtls_ctr_drbg_context structure.
output	The buffer to fill.
output_len	The length of the buffer.
additional	Additional data to update. Can be NULL.
add_len	The length of the additional data.

Returns:: 0 on success, or MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED or MBEDTLS_ERR_CTR_DRBG_REQUEST_TOO_BIG on failure.

Definition at line 378 of file ctr_drbg.c.

int mbedtls_ctr_drbg_reseed	(	mbedtls_ctr_drbg_context *	ctx,
		const unsigned char *	additional,
		size_t	len
	)

This function reseeds the CTR_DRBG context, that is extracts data from the entropy source.

Parameters:

ctx	The CTR_DRBG context.
additional	Additional data to add to the state. Can be NULL.
len	The length of the additional data.

Returns:: 0 on success, or MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED on failure.

Definition at line 325 of file ctr_drbg.c.

int mbedtls_ctr_drbg_seed	(	mbedtls_ctr_drbg_context *	ctx,
		int()(void , unsigned char *, size_t)	f_entropy,
		void *	p_entropy,
		const unsigned char *	custom,
		size_t	len
	)

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.

Parameters:

ctx	The CTR_DRBG context to seed.
f_entropy	The entropy callback, taking as arguments the `p_entropy` context, the buffer to fill, and the length of the buffer.
p_entropy	The entropy context.
custom	Personalization data, that is device-specific identifiers. Can be NULL.
len	The length of the personalization data.

Returns:: 0 on success, or MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED on failure.

Definition at line 109 of file ctr_drbg.c.

int mbedtls_ctr_drbg_self_test ( int verbose )

The CTR_DRBG checkup routine.

Returns:: 0 on success, or 1 on failure.

Definition at line 600 of file ctr_drbg.c.

void mbedtls_ctr_drbg_set_entropy_len	(	mbedtls_ctr_drbg_context *	ctx,
		size_t	len
	)

This function sets the amount of entropy grabbed on each seed or reseed.

The default value is MBEDTLS_CTR_DRBG_ENTROPY_LEN.

Parameters:

ctx	The CTR_DRBG context.
len	The amount of entropy to grab.

Definition at line 136 of file ctr_drbg.c.

void mbedtls_ctr_drbg_set_prediction_resistance	(	mbedtls_ctr_drbg_context *	ctx,
		int	resistance
	)

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.

Parameters:

ctx	The CTR_DRBG context.
resistance	MBEDTLS_CTR_DRBG_PR_ON or MBEDTLS_CTR_DRBG_PR_OFF.

Definition at line 131 of file ctr_drbg.c.

void mbedtls_ctr_drbg_set_reseed_interval	(	mbedtls_ctr_drbg_context *	ctx,
		int	interval
	)

This function sets the reseed interval.

The default value is MBEDTLS_CTR_DRBG_RESEED_INTERVAL.

Parameters:

ctx	The CTR_DRBG context.
interval	The reseed interval.

Definition at line 141 of file ctr_drbg.c.

void mbedtls_ctr_drbg_update	(	mbedtls_ctr_drbg_context *	ctx,
		const unsigned char *	additional,
		size_t	add_len
	)

This function updates the state of the CTR_DRBG context.

Parameters:

ctx	The CTR_DRBG context.
additional	The data to update the state with.
add_len	Length of `additional` data.

Note:: If 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.

Definition at line 308 of file ctr_drbg.c.

int mbedtls_ctr_drbg_update_seed_file	(	mbedtls_ctr_drbg_context *	ctx,
		const char *	path
	)

This function reads and updates a seed file.

The seed is added to this instance.

Parameters:

ctx	The CTR_DRBG context.
path	The name of the file.

Returns:: 0 on success, MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR on file error, MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED or MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG on failure.

Definition at line 502 of file ctr_drbg.c.

int mbedtls_ctr_drbg_write_seed_file	(	mbedtls_ctr_drbg_context *	ctx,
		const char *	path
	)

This function writes a seed file.

Parameters:

ctx	The CTR_DRBG context.
path	The name of the file.

Returns:: 0 on success, MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR on file error, or MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED on failure.

Definition at line 478 of file ctr_drbg.c.

Type:	Program
Mbed OS support:	Mbed OS
Created:	29 Mar 2018
Imports:	22
Forks:	0
Commits:	5
Dependents:	0
Dependencies:	0
Followers:	6

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