EVP_KDF-PBKDF2(7ossl)

📦
version 15.1 · 3 versions
, in freebsd 15.1

💖 EVP_KDF-PBKDF2 — the PBKDF2 EVP_KDF implementation (manpage fam: 7ossl) 💖

okay so bestie, welcome to the glow-up of password-based key derivation ✨ this whole page lives in the OpenSSL 7ossl section and it's genuinely one of the most useful little corners of the manual, so let's get into it 🫶

🌸 NAME 🌸

EVP_KDF-PBKDF2 — the PBKDF2 EVP_KDF implementation, aka the thing that turns your password into a key 🔑

✨ DESCRIPTION ✨

So basically this is the 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. iconic behaviour, no cap 👑

The output is considered to be a cryptographic key. yes bestie, an actual key, treat it with respect 🎀

🦋 Identity 🦋

"PBKDF2" is the name for this implementation; it can be used with the EVP_KDF_fetch() function. that's the string you're gonna be throwing around, iykyk 💫

🌈 Supported parameters 🌈

The supported parameters are:

  • "pass" (OSSL_KDF_PARAM_PASSWORD) <octet string> — the password goes here, as raw octets 💜
  • "salt" (OSSL_KDF_PARAM_SALT) <octet string> — and here's your salt, also octets 🧂
  • "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> — a properties string, works exactly as described in "PARAMETERS" in EVP_KDF(3) 🌸
  • "digest" (OSSL_KDF_PARAM_DIGEST) <UTF8 string> — the digest to use, and 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 💀 (yes, that's a real caveat, don't skip it)

  • "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 🔥

📝 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. classic combo, honestly obsessed 🎀

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, turning that number up is your friend, fr fr 🛡️

No assumption is made regarding the given password; it is simply treated as a byte sequence. no vibes check, no validation, just bytes bestie 🫶

👑 CONFORMING TO 👑

SP800-132 ⭐

🔍 SEE ALSO 🔍

go read them, they're all part of the lore 💅

🕰️ HISTORY 🕰️

This functionality was added in OpenSSL 3.0. she's not ancient, she's just iconic 🌸

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>.

🎀 that's the whole page bestie, every flag, every default, every compliance check — nothing skipped, periodt 💅

and that's a wrap on the EVP_KDF-PBKDF2 7ossl page, brought to you by version 3.5.6, dated 2026-04-07 — go forth and derive responsibly 🌈✨🦋

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