- NAME
- DESCRIPTION
  - Identity
  - Supported parameters
- NOTES
- CONFORMING TO
- SEE ALSO
- HISTORY
- COPYRIGHT

# NAME

EVP_KDF-PBKDF2 - The PBKDF2 EVP_KDF implementation

# DESCRIPTION

Support for computing the PBKDF2 password-based KDF through the EVP_KDF API.

The EVP_KDF-PBKDF2 algorithm implements the PBKDF2 password-based key derivation function, as described in SP800-132; it derives a key from a password using a salt and iteration count.

The output is considered to be a cryptographic key.

## Identity

"PBKDF2" is the name for this implementation; it can be used with the EVP_KDF_fetch() function.

## Supported parameters

The supported parameters are:

"pass" (OSSL_KDF_PARAM_PASSWORD) <octet string>
"salt" (OSSL_KDF_PARAM_SALT) <octet string>
"iter" (OSSL_KDF_PARAM_ITER) <unsigned integer>

  This parameter has a default value of 2048.

"properties" (OSSL_KDF_PARAM_PROPERTIES) <UTF8 string>
"digest" (OSSL_KDF_PARAM_DIGEST) <UTF8 string>

  These parameters work as described in "PARAMETERS" in EVP_KDF(3).

  Note: PBKDF2 uses HMAC internally, which does not support eXtendable Output Function (XOF) digests such as SHAKE128 or SHAKE256. Attempting to use an XOF digest with PBKDF2 will result in an error.

"pkcs5" (OSSL_KDF_PARAM_PKCS5) <integer>

  This parameter can be used to enable or disable SP800-132 compliance checks. Setting the mode to 0 enables the compliance checks.

  The checks performed are:

  - the iteration count is at least 1000.
  - the salt length is at least 128 bits.
  - the derived key length is at least 112 bits.
  - the password length is at least minimum length.

    The default minimum password length can be configured when OpenSSL is compiled by setting -DKDF_PBKDF2_MIN_PASSWORD_LEN=length. If not set then 1 is used for the default provider and 8 for the FIPS provider since 4.0.0. Please consult the security policy document of your FIPS provider from your vendor for further details, as implementation often vary by each vendor.

  The default provider uses a default mode of 1 for backwards compatibility, and the FIPS provider uses a default mode of 0. This option breaks FIPS compliance if it causes the approved "fips-indicator" to return 0.

"fips-indicator" (OSSL_KDF_PARAM_FIPS_APPROVED_INDICATOR) <integer>

  This option is used by the OpenSSL FIPS provider.

  A getter that returns 1 if the operation is FIPS approved, or 0 otherwise. This may be used after calling EVP_KDF_derive. It returns 0 if "pkcs5" is set to 1 and the password length, derived key length, salt length or iteration count test fails.

# NOTES

A typical application of this algorithm is to derive keying material for an encryption algorithm from a password in the "pass", a salt in "salt", and an iteration count.

Increasing the "iter" parameter slows down the algorithm which makes it harder for an attacker to perform a brute force attack using a large number of candidate passwords.

No assumption is made regarding the given password; it is simply treated as a byte sequence.

# CONFORMING TO

SP800-132

# SEE ALSO

EVP_KDF(3), EVP_KDF_CTX_new(3), EVP_KDF_CTX_free(3), EVP_KDF_CTX_set_params(3), EVP_KDF_derive(3), "PARAMETERS" in EVP_KDF(3)

# HISTORY

This functionality was added in OpenSSL 3.0.

# COPYRIGHT

Copyright 2018-2026 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.