---
name: "EVP_KDF-HMAC-DRBG"
section: "7ssl"
platform: "linux"
package: "openssl"
version: "3.6.5-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/EVP_KDF-HMAC-DRBG"
---

# EVP\_KDF-HMAC-DRBG(7ssl)

The HMAC DRBG DETERMINISTIC EVP\_KDF implementation

## NAME

EVP\_KDF-HMAC-DRBG - The HMAC DRBG DETERMINISTIC EVP\_KDF implementation

## DESCRIPTION

Support for a deterministic HMAC DRBG using the **EVP\_KDF** API. This is similar to **EVP\_RAND-HMAC-DRBG**(7), but uses fixed values for its entropy and nonce values. This is used to generate deterministic nonce value required by ECDSA and DSA (as defined in RFC 6979).

### Identity

"HMAC-DRBG-KDF" is the name for this implementation; it can be used with the **EVP\_KDF\_fetch()** function.

### Supported parameters

The supported parameters are:

- "digest" (**OSSL\_DRBG\_PARAM\_DIGEST**) \<UTF8 string\>

  - "properties" (**OSSL\_DRBG\_PARAM\_PROPERTIES**) \<UTF8 string\>

  These parameters work as described in "PARAMETERS" in **EVP\_KDF**(3).

- "entropy" (**OSSL\_KDF\_PARAM\_HMACDRBG\_ENTROPY**) \<octet string\>

  Sets the entropy bytes supplied to the HMAC-DRBG.

- "nonce" (**OSSL\_KDF\_PARAM\_HMACDRBG\_NONCE**) \<octet string\>

  Sets the nonce bytes supplied to the HMAC-DRBG.

## NOTES

A context for KDF HMAC DRBG can be obtained by calling:

```
 EVP_KDF *kdf = EVP_KDF_fetch(NULL, "HMAC-DRBG-KDF", NULL);
 EVP_KDF_CTX *kdf_ctx = EVP_KDF_CTX_new(kdf, NULL);
```

## CONFORMING TO

RFC 6979

## SEE ALSO

**EVP\_KDF**(3), "PARAMETERS" in **EVP\_KDF**(3)

## HISTORY

The EVP\_KDF-HMAC-DRBG functionality was added in OpenSSL 3.2.

## COPYRIGHT

Copyright 2022-2023 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\>.