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mbedtls_ctr_drbg_context struct
The CTR_DRBG context structure.
Syntax
typedef struct mbedtls_ctr_drbg_context
{
unsigned char counter[16];
int reseed_counter;
int prediction_resistance;
size_t entropy_len;
int reseed_interval;
mbedtls_aes_context aes_ctx;
int (*f_entropy)(void *, unsigned char *, size_t);
void *p_entropy;
#if defined(MBEDTLS_THREADING_C)
mbedtls_threading_mutex_t mutex;
#endif
}
mbedtls_ctr_drbg_context;
Fields
Field
Declared as
Description
int
The reseed counter. This is the number of requests that have been made since the last (re)seeding, minus one. Before the initial seeding, this field contains the amount of entropy in bytes to use as a nonce for the initial seeding, or -1 if no nonce length has been explicitly set (see mbedtls_ctr_drbg_set_nonce_len()).
int
This determines whether prediction resistance is enabled, that is whether to systematically reseed before each random generation.
size_t
The amount of entropy grabbed on each seed or reseed operation, in bytes.
int
The reseed interval. This is the maximum number of requests that can be made between reseedings.
int (*)(void *, unsigned char *, size_t)
The entropy callback function.
Related Functions
Found 15 other functions taking a mbedtls_ctr_drbg_context
argument:
Function
Description
This function initializes the CTR_DRBG context, and prepares it for mbedtls_ctr_drbg_seed() or mbedtls_ctr_drbg_free().
This function resets CTR_DRBG context to the state immediately after initial call of mbedtls_ctr_drbg_init().
This function updates the state of the CTR_DRBG context.
This function reseeds the CTR_DRBG context, that is extracts data from the entropy source.
- The \p custom string. In addition, if you do not pass a nonce in \p custom, the sum of the entropy length and the entropy nonce length must be: - at least 24 bytes for a 128-bit strength (maximum achievable strength when using AES-128); - at least 48 bytes for a 256-bit strength (maximum achievable strength when using AES-256).
This function sets the amount of entropy grabbed as a nonce for the initial seeding. Call this function before calling mbedtls_ctr_drbg_seed() to read a nonce from the entropy source during the initial seeding.
This function sets the reseed interval. The reseed interval is the number of calls to mbedtls_ctr_drbg_random() or mbedtls_ctr_drbg_random_with_add() after which the entropy function is called again. The default value is #MBEDTLS_CTR_DRBG_RESEED_INTERVAL.
This function turns prediction resistance on or off. The default value is off.
This function sets the amount of entropy grabbed on each seed or reseed. The default value is #MBEDTLS_CTR_DRBG_ENTROPY_LEN.