# EVP_RAND-HASH-DRBG - man(7SSL) - [phpMan]

[_EVP_RAND-HASH-DRBG_(7SSL)](https://www.chedong.com/phpMan.php/man/EVPRAND-HASH-DRBG/7SSL/markdown)                       OpenSSL                      [_EVP_RAND-HASH-DRBG_(7SSL)](https://www.chedong.com/phpMan.php/man/EVPRAND-HASH-DRBG/7SSL/markdown)

## NAME
       EVP_RAND-HASH-DRBG - The HASH DRBG EVP_RAND implementation

## DESCRIPTION
       Support for the hash deterministic random bit generator through the **EVP_RAND **API.

### Identity
       "HASH-DRBG" is the name for this implementation; it can be used with the **EVP_RAND_fetch()**
       function.

### Supported parameters
       The supported parameters are:

       "state" (**OSSL_RAND_PARAM_STATE**) <integer>
       "strength" (**OSSL_RAND_PARAM_STRENGTH**) <unsigned integer>
       "max_request" (**OSSL_RAND_PARAM_MAX_REQUEST**) <unsigned integer>
       "reseed_requests" (**OSSL_DRBG_PARAM_RESEED_REQUESTS**) <unsigned integer>
       "reseed_time_interval" (**OSSL_DRBG_PARAM_RESEED_TIME_INTERVAL**) <integer>
       "min_entropylen" (**OSSL_DRBG_PARAM_MIN_ENTROPYLEN**) <unsigned integer>
       "max_entropylen" (**OSSL_DRBG_PARAM_MAX_ENTROPYLEN**) <unsigned integer>
       "min_noncelen" (**OSSL_DRBG_PARAM_MIN_NONCELEN**) <unsigned integer>
       "max_noncelen" (**OSSL_DRBG_PARAM_MAX_NONCELEN**) <unsigned integer>
       "max_perslen" (**OSSL_DRBG_PARAM_MAX_PERSLEN**) <unsigned integer>
       "max_adinlen" (**OSSL_DRBG_PARAM_MAX_ADINLEN**) <unsigned integer>
       "reseed_counter" (**OSSL_DRBG_PARAM_RESEED_COUNTER**) <unsigned integer>
       "properties" (**OSSL_DRBG_PARAM_PROPERTIES**) <UTF8 string>
       "digest" (**OSSL_DRBG_PARAM_DIGEST**) <UTF8 string>
           These parameters work as described in "PARAMETERS" in [**EVP_RAND**(3)](https://www.chedong.com/phpMan.php/man/EVPRAND/3/markdown).

## NOTES
       A context for HASH DRBG can be obtained by calling:

        EVP_RAND *rand = EVP_RAND_fetch(NULL, "HASH-DRBG", NULL);
        EVP_RAND_CTX *rctx = EVP_RAND_CTX_new(rand);

## EXAMPLES
        EVP_RAND *rand;
        EVP_RAND_CTX *rctx;
        unsigned char bytes[100];
        OSSL_PARAM params[2], *p = params;
        unsigned int strength = 128;

        rand = EVP_RAND_fetch(NULL, "HASH-DRBG", NULL);
        rctx = EVP_RAND_CTX_new(rand, NULL);
        EVP_RAND_free(rand);

        *p++ = OSSL_PARAM_construct_utf8_string(OSSL_DRBG_PARAM_DIGEST, SN_sha512, 0);
        *p = OSSL_PARAM_construct_end();
        EVP_RAND_instantiate(rctx, strength, 0, NULL, 0, params);

        EVP_RAND_generate(rctx, bytes, sizeof(bytes), strength, 0, NULL, 0);

        EVP_RAND_CTX_free(rctx);

## CONFORMING TO
       NIST SP 800-90A and SP 800-90B

## SEE ALSO
       [**EVP_RAND**(3)](https://www.chedong.com/phpMan.php/man/EVPRAND/3/markdown), "PARAMETERS" in [**EVP_RAND**(3)](https://www.chedong.com/phpMan.php/man/EVPRAND/3/markdown)

## COPYRIGHT
       Copyright 2020-2021 The OpenSSL Project Authors. All Rights Reserved.

       Licensed  under  the Apache License 2.0 (the "License").  You may not use this file except in
       compliance with the License.  You can obtain a  copy  in  the  file  LICENSE  in  the  source
       distribution or at <<https://www.openssl.org/source/license.html>>.

3.0.13                                       2026-07-29                     [_EVP_RAND-HASH-DRBG_(7SSL)](https://www.chedong.com/phpMan.php/man/EVPRAND-HASH-DRBG/7SSL/markdown)