EVP_RAND-HMAC-DRBG7ssl

The hmac drbg evp_rand implementation

Overview

Support for the HMAC deterministic random bit generator through the EVP_RAND API.

Identity

"HMAC-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>

"mac" (OSSL_DRBG_PARAM_MAC) <UTF8 string>

"digest" (OSSL_DRBG_PARAM_DIGEST) <UTF8 string>: These parameters work as described in "PARAMETERS" in EVP_RAND(3).

"fips-indicator" (OSSL_DRBG_PARAM_FIPS_APPROVED_INDICATOR) <integer>

"digest-check" (OSSL_DRBG_PARAM_FIPS_DIGEST_CHECK) <integer>: These parameters work as described in "PARAMETERS" in provider-rand(7).

Notes

When using the FIPS provider, only these digests are permitted (as per FIPS 140-3 IG D.R <https://csrc.nist.gov/CSRC/media/Projects/cryptographic-module-validation-program/documents/fips%20140-3/FIPS%20140-3%20IG.pdf>):

The default HMAC-DRBG implementation attempts to fetch the required internal algorithms from the provider they are built into (eg the default provider) regardless of the properties provided. Should the provider not implement the required algorithms then properties will be used to find a different implementation.

SHA-1

SHA2-256

SHA2-512

SHA3-256

SHA3-512

A context for HMAC DRBG can be obtained by calling:

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

Examples

 EVP_RAND *rand;
 EVP_RAND_CTX *rctx;
 unsigned char bytes[100];
 OSSL_PARAM params[3], *p = params;
 unsigned int strength = 128;
 rand = EVP_RAND_fetch(NULL, "HMAC-DRBG", NULL);
 rctx = EVP_RAND_CTX_new(rand, NULL);
 EVP_RAND_free(rand);
 *p++ = OSSL_PARAM_construct_utf8_string(OSSL_DRBG_PARAM_MAC, SN_hmac, 0);
 *p++ = OSSL_PARAM_construct_utf8_string(OSSL_DRBG_PARAM_DIGEST, SN_sha256, 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);

Releases

3 releases since Debian 12 (Bookworm); the text changed 2 times.