ctr_drbg.h File Reference

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...

#include "aes.h"
Include dependency graph for ctr_drbg.h:

Go to the source code of this file.

Data Structures

struct  mbedtls_ctr_drbg_context
 The CTR_DRBG context structure. More...

Defines

#define MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED   -0x0034
#define MBEDTLS_ERR_CTR_DRBG_REQUEST_TOO_BIG   -0x0036
#define MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG   -0x0038
#define MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR   -0x003A
#define MBEDTLS_CTR_DRBG_BLOCKSIZE   16
#define MBEDTLS_CTR_DRBG_KEYSIZE   32
#define MBEDTLS_CTR_DRBG_KEYBITS   ( MBEDTLS_CTR_DRBG_KEYSIZE * 8 )
#define MBEDTLS_CTR_DRBG_SEEDLEN   ( MBEDTLS_CTR_DRBG_KEYSIZE + MBEDTLS_CTR_DRBG_BLOCKSIZE )
#define MBEDTLS_CTR_DRBG_PR_OFF   0
#define MBEDTLS_CTR_DRBG_PR_ON   1
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.



#define MBEDTLS_CTR_DRBG_ENTROPY_LEN   48
#define MBEDTLS_CTR_DRBG_RESEED_INTERVAL   10000
#define MBEDTLS_CTR_DRBG_MAX_INPUT   256
#define MBEDTLS_CTR_DRBG_MAX_REQUEST   1024
#define MBEDTLS_CTR_DRBG_MAX_SEED_INPUT   384

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. The default value is 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. The default value is MBEDTLS_CTR_DRBG_ENTROPY_LEN.
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.
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. The seed is added to this instance.
int mbedtls_ctr_drbg_self_test (int verbose)
 The CTR_DRBG checkup routine.
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)

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.


Define Documentation

#define MBEDTLS_CTR_DRBG_BLOCKSIZE   16

The block size used by the cipher.

Definition at line 42 of file ctr_drbg.h.

#define MBEDTLS_CTR_DRBG_ENTROPY_LEN   48

The amount of entropy used per seed by default:

  • 48 with SHA-512.
  • 32 with SHA-256.

Definition at line 58 of file ctr_drbg.h.

#define MBEDTLS_CTR_DRBG_KEYBITS   ( MBEDTLS_CTR_DRBG_KEYSIZE * 8 )

The key size for the DRBG operation, in bits.

Definition at line 44 of file ctr_drbg.h.

#define MBEDTLS_CTR_DRBG_KEYSIZE   32

The key size used by the cipher.

Definition at line 43 of file ctr_drbg.h.

#define MBEDTLS_CTR_DRBG_MAX_INPUT   256

The maximum number of additional input Bytes.

Definition at line 78 of file ctr_drbg.h.

#define MBEDTLS_CTR_DRBG_MAX_REQUEST   1024

The maximum number of requested Bytes per call.

Definition at line 83 of file ctr_drbg.h.

#define MBEDTLS_CTR_DRBG_MAX_SEED_INPUT   384

The maximum size of seed or reseed buffer.

Definition at line 88 of file ctr_drbg.h.

#define MBEDTLS_CTR_DRBG_PR_OFF   0

Prediction resistance is disabled.

Definition at line 94 of file ctr_drbg.h.

#define MBEDTLS_CTR_DRBG_PR_ON   1

Prediction resistance is enabled.

Definition at line 96 of file ctr_drbg.h.

#define MBEDTLS_CTR_DRBG_RESEED_INTERVAL   10000

The interval before reseed is performed by default.

Definition at line 73 of file ctr_drbg.h.

#define MBEDTLS_CTR_DRBG_SEEDLEN   ( MBEDTLS_CTR_DRBG_KEYSIZE + MBEDTLS_CTR_DRBG_BLOCKSIZE )

The seed length, calculated as (counter + AES key).

Definition at line 45 of file ctr_drbg.h.

#define MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED   -0x0034

The entropy source failed.

Definition at line 37 of file ctr_drbg.h.

#define MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR   -0x003A

Read or write error in file.

Definition at line 40 of file ctr_drbg.h.

#define MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG   -0x0038

The input (entropy + additional data) is too large.

Definition at line 39 of file ctr_drbg.h.

#define MBEDTLS_ERR_CTR_DRBG_REQUEST_TOO_BIG   -0x0036

The requested random buffer length is too big.

Definition at line 38 of 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.
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.
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.
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.
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.
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.
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   
)
int mbedtls_ctr_drbg_self_test ( int  verbose  ) 

The CTR_DRBG checkup routine.

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

Generated on 19 Sep 2018 for mbed TLS v2.7.6 by  doxygen 1.6.1