mbed TLS  Version 2.9.0
SSL/TLS Library for the Embedded Space
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hmac_drbg.h File Reference

Data Structures

struct  mbedtls_hmac_drbg_context
 HMAC_DRBG context. More...
 

Macros

#define MBEDTLS_ERR_HMAC_DRBG_REQUEST_TOO_BIG   -0x0003
 Too many random requested in single call. More...
 
#define MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG   -0x0005
 Input too large (Entropy + additional). More...
 
#define MBEDTLS_ERR_HMAC_DRBG_FILE_IO_ERROR   -0x0007
 Read/write error in file. More...
 
#define MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED   -0x0009
 The entropy source failed. More...
 
#define MBEDTLS_HMAC_DRBG_PR_OFF   0
 No prediction resistance.
 
#define MBEDTLS_HMAC_DRBG_PR_ON   1
 Prediction resistance enabled.
 
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 on the compiler command line.

#define MBEDTLS_HMAC_DRBG_RESEED_INTERVAL   10000
 Interval before reseed is performed by default.
 
#define MBEDTLS_HMAC_DRBG_MAX_INPUT   256
 Maximum number of additional input bytes.
 
#define MBEDTLS_HMAC_DRBG_MAX_REQUEST   1024
 Maximum number of requested bytes per call.
 
#define MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT   384
 Maximum size of (re)seed buffer.
 

Functions

void mbedtls_hmac_drbg_init (mbedtls_hmac_drbg_context *ctx)
 HMAC_DRBG context initialization Makes the context ready for mbedtls_hmac_drbg_seed(), mbedtls_hmac_drbg_seed_buf() or mbedtls_hmac_drbg_free(). More...
 
int mbedtls_hmac_drbg_seed (mbedtls_hmac_drbg_context *ctx, const mbedtls_md_info_t *md_info, int(*f_entropy)(void *, unsigned char *, size_t), void *p_entropy, const unsigned char *custom, size_t len)
 HMAC_DRBG initial seeding Seed and setup entropy source for future reseeds. More...
 
int mbedtls_hmac_drbg_seed_buf (mbedtls_hmac_drbg_context *ctx, const mbedtls_md_info_t *md_info, const unsigned char *data, size_t data_len)
 Initilisation of simpified HMAC_DRBG (never reseeds). More...
 
void mbedtls_hmac_drbg_set_prediction_resistance (mbedtls_hmac_drbg_context *ctx, int resistance)
 Enable / disable prediction resistance (Default: Off) More...
 
void mbedtls_hmac_drbg_set_entropy_len (mbedtls_hmac_drbg_context *ctx, size_t len)
 Set the amount of entropy grabbed on each reseed (Default: given by the security strength, which depends on the hash used, see mbedtls_hmac_drbg_init() ) More...
 
void mbedtls_hmac_drbg_set_reseed_interval (mbedtls_hmac_drbg_context *ctx, int interval)
 Set the reseed interval (Default: MBEDTLS_HMAC_DRBG_RESEED_INTERVAL) More...
 
void mbedtls_hmac_drbg_update (mbedtls_hmac_drbg_context *ctx, const unsigned char *additional, size_t add_len)
 HMAC_DRBG update state. More...
 
int mbedtls_hmac_drbg_reseed (mbedtls_hmac_drbg_context *ctx, const unsigned char *additional, size_t len)
 HMAC_DRBG reseeding (extracts data from entropy source) More...
 
int mbedtls_hmac_drbg_random_with_add (void *p_rng, unsigned char *output, size_t output_len, const unsigned char *additional, size_t add_len)
 HMAC_DRBG generate random with additional update input. More...
 
int mbedtls_hmac_drbg_random (void *p_rng, unsigned char *output, size_t out_len)
 HMAC_DRBG generate random. More...
 
void mbedtls_hmac_drbg_free (mbedtls_hmac_drbg_context *ctx)
 Free an HMAC_DRBG context. More...
 
int mbedtls_hmac_drbg_write_seed_file (mbedtls_hmac_drbg_context *ctx, const char *path)
 Write a seed file. More...
 
int mbedtls_hmac_drbg_update_seed_file (mbedtls_hmac_drbg_context *ctx, const char *path)
 Read and update a seed file. More...
 
int mbedtls_hmac_drbg_self_test (int verbose)
 Checkup routine. More...
 

Description

HMAC_DRBG (NIST SP 800-90A)

Macro Definition Documentation

#define MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED   -0x0009

The entropy source failed.

#define MBEDTLS_ERR_HMAC_DRBG_FILE_IO_ERROR   -0x0007

Read/write error in file.

#define MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG   -0x0005

Input too large (Entropy + additional).

#define MBEDTLS_ERR_HMAC_DRBG_REQUEST_TOO_BIG   -0x0003

Too many random requested in single call.

Function Documentation

void mbedtls_hmac_drbg_free ( mbedtls_hmac_drbg_context ctx)

Free an HMAC_DRBG context.

Parameters
ctxHMAC_DRBG context to free.
void mbedtls_hmac_drbg_init ( mbedtls_hmac_drbg_context ctx)

HMAC_DRBG context initialization Makes the context ready for mbedtls_hmac_drbg_seed(), mbedtls_hmac_drbg_seed_buf() or mbedtls_hmac_drbg_free().

Parameters
ctxHMAC_DRBG context to be initialized
int mbedtls_hmac_drbg_random ( void *  p_rng,
unsigned char *  output,
size_t  out_len 
)

HMAC_DRBG generate random.

Note: Automatically reseeds if reseed_counter is reached or PR is enabled.

Parameters
p_rngHMAC_DRBG context
outputBuffer to fill
out_lenLength of the buffer
Returns
0 if successful, or MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED, or MBEDTLS_ERR_HMAC_DRBG_REQUEST_TOO_BIG
int mbedtls_hmac_drbg_random_with_add ( void *  p_rng,
unsigned char *  output,
size_t  output_len,
const unsigned char *  additional,
size_t  add_len 
)

HMAC_DRBG generate random with additional update input.

Note: Automatically reseeds if reseed_counter is reached or PR is enabled.

Parameters
p_rngHMAC_DRBG context
outputBuffer to fill
output_lenLength of the buffer
additionalAdditional data to update with (can be NULL)
add_lenLength of additional data (can be 0)
Returns
0 if successful, or MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED, or MBEDTLS_ERR_HMAC_DRBG_REQUEST_TOO_BIG, or MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG.
int mbedtls_hmac_drbg_reseed ( mbedtls_hmac_drbg_context ctx,
const unsigned char *  additional,
size_t  len 
)

HMAC_DRBG reseeding (extracts data from entropy source)

Parameters
ctxHMAC_DRBG context
additionalAdditional data to add to state (Can be NULL)
lenLength of additional data
Returns
0 if successful, or MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED
int mbedtls_hmac_drbg_seed ( mbedtls_hmac_drbg_context ctx,
const mbedtls_md_info_t md_info,
int(*)(void *, unsigned char *, size_t)  f_entropy,
void *  p_entropy,
const unsigned char *  custom,
size_t  len 
)

HMAC_DRBG initial seeding Seed and setup entropy source for future reseeds.

Parameters
ctxHMAC_DRBG context to be seeded
md_infoMD algorithm to use for HMAC_DRBG
f_entropyEntropy callback (p_entropy, buffer to fill, buffer length)
p_entropyEntropy context
customPersonalization data (Device specific identifiers) (Can be NULL)
lenLength of personalization data
Note
The "security strength" as defined by NIST is set to: 128 bits if md_alg is SHA-1, 192 bits if md_alg is SHA-224, 256 bits if md_alg is SHA-256 or higher. Note that SHA-256 is just as efficient as SHA-224.
Returns
0 if successful, or MBEDTLS_ERR_MD_BAD_INPUT_DATA, or MBEDTLS_ERR_MD_ALLOC_FAILED, or MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED.
int mbedtls_hmac_drbg_seed_buf ( mbedtls_hmac_drbg_context ctx,
const mbedtls_md_info_t md_info,
const unsigned char *  data,
size_t  data_len 
)

Initilisation of simpified HMAC_DRBG (never reseeds).

(For use with deterministic ECDSA.)

Parameters
ctxHMAC_DRBG context to be initialised
md_infoMD algorithm to use for HMAC_DRBG
dataConcatenation of entropy string and additional data
data_lenLength of data in bytes
Returns
0 if successful, or MBEDTLS_ERR_MD_BAD_INPUT_DATA, or MBEDTLS_ERR_MD_ALLOC_FAILED.
int mbedtls_hmac_drbg_self_test ( int  verbose)

Checkup routine.

Returns
0 if successful, or 1 if the test failed
void mbedtls_hmac_drbg_set_entropy_len ( mbedtls_hmac_drbg_context ctx,
size_t  len 
)

Set the amount of entropy grabbed on each reseed (Default: given by the security strength, which depends on the hash used, see mbedtls_hmac_drbg_init() )

Parameters
ctxHMAC_DRBG context
lenAmount of entropy to grab, in bytes
void mbedtls_hmac_drbg_set_prediction_resistance ( mbedtls_hmac_drbg_context ctx,
int  resistance 
)

Enable / disable prediction resistance (Default: Off)

Note: If enabled, entropy is used for ctx->entropy_len before each call! Only use this if you have ample supply of good entropy!

Parameters
ctxHMAC_DRBG context
resistanceMBEDTLS_HMAC_DRBG_PR_ON or MBEDTLS_HMAC_DRBG_PR_OFF
void mbedtls_hmac_drbg_set_reseed_interval ( mbedtls_hmac_drbg_context ctx,
int  interval 
)

Set the reseed interval (Default: MBEDTLS_HMAC_DRBG_RESEED_INTERVAL)

Parameters
ctxHMAC_DRBG context
intervalReseed interval
void mbedtls_hmac_drbg_update ( mbedtls_hmac_drbg_context ctx,
const unsigned char *  additional,
size_t  add_len 
)

HMAC_DRBG update state.

Parameters
ctxHMAC_DRBG context
additionalAdditional data to update state with, or NULL
add_lenLength of additional data, or 0
Note
Additional data is optional, pass NULL and 0 as second third argument if no additional data is being used.
int mbedtls_hmac_drbg_update_seed_file ( mbedtls_hmac_drbg_context ctx,
const char *  path 
)

Read and update a seed file.

Seed is added to this instance

Parameters
ctxHMAC_DRBG context
pathName of the file
Returns
0 if successful, 1 on file error, MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED or MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG
int mbedtls_hmac_drbg_write_seed_file ( mbedtls_hmac_drbg_context ctx,
const char *  path 
)

Write a seed file.

Parameters
ctxHMAC_DRBG context
pathName of the file
Returns
0 if successful, 1 on file error, or MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED