EVP_KDF-PBKDF2(7ossl)

📦
version 3.5.9 · 8 versions
, in alpine 3.23, alpine 3.24

💖 EVP_KDF-PBKDF2 💖

okay so bestie, welcome to the OpenSSL manual — this page is EVP_KDF-PBKDF2(7ossl) and it's literally all about turning a password into a key. grab a snack, we're getting into it 🍓

✨ NAME ✨

EVP_KDF-PBKDF2 — the PBKDF2 EVP_KDF implementation, no cap 🫶

🌸 DESCRIPTION 🌸

Support for computing the PBKDF2 password-based KDF through the EVP_KDF API. yes, that's the whole vibe 💅

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. iconic behavior fr fr 👑

The output is considered to be a cryptographic key. like, that's the whole point, that's the main character energy right there 🔥

🦋 Identity 🦋

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

🎀 Supported parameters 🎀

The supported parameters are, and yes you need to know all of them:

  • "pass" (OSSL_KDF_PARAM_PASSWORD) <octet string> — the password bestie, it's giving "the secret"
  • "salt" (OSSL_KDF_PARAM_SALT) <octet string> — the salt, sprinkle it in 💜
  • "iter" (OSSL_KDF_PARAM_ITER) <unsigned integer> — the iteration count. This parameter has a default value of 2048. 🌀
  • "properties" (OSSL_KDF_PARAM_PROPERTIES) <UTF8 string> — yes this one
  • "digest" (OSSL_KDF_PARAM_DIGEST) <UTF8 string> — and this one. These parameters work as described in "PARAMETERS" in EVP_KDF(3).
  • "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 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. 💀 careful bestie.
  • "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 derived key length, salt length or iteration count test fails. 😭 that's the vibe check failing.

🌈 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. that's the standard group-chat recipe fr fr 🎀

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. so like, turn it UP 💅🔥

No assumption is made regarding the given password; it is simply treated as a byte sequence. it's literally just bytes, no judgment, periodt 🦋

💫 CONFORMING TO 💫

SP800-132 — witnessed, stamped, approved 👑

⭐ SEE ALSO ⭐

go read these too, i'm obsessed:

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. she's been here a minute 💜

Copyright 2018-2024 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>.

and that's the whole page bestie, mwah 💋 — this was version 3.5.9, dated 2026-09-29, and it's EVP_KDF-PBKDF2(7ossl) signing off. slay, stay safe, and keep your iteration counts high 🫶✨

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