I see many references to KDF2 here, but all links are broken and Wikipedia does not have an entry for KDF2. Is KDF2 a specific standard for Key Derivation without a password?

Ultimately, I am trying to make sense of why KDF2 is listed as PRNG for Crypto++ on Wikipedia.

  • $\begingroup$ KDF2 is a specific standard for key-based key derivation. $\endgroup$
    – SEJPM
    Jul 19, 2017 at 15:22

1 Answer 1


KDF2 is a KDF defined in ISO 18033. You can find a draft of that spec here. See section 6.2.3.

As to why it's listed as a PRNG, remember that a KDF relies on a pseudo random function (PRF), so it's output needs to be random.

  • 1
    $\begingroup$ It can be considered a PRNG in the same sense that AES-CTR is one. $\endgroup$
    – SEJPM
    Jul 19, 2017 at 18:33
  • 2
    $\begingroup$ I don't think any PRF should be called a PRNG. For a PRNG I would at least expect an option to re-seed, even if that re-seeding operation would take a statically sized input. I would also expect it to return numbers rather than bits; DRBG would otherwise be a more apt name. It's unfortunate that these kinds of concepts get mixed up all the time. But yeah, KDF's and CTR mode are sometimes called PRNG's :( $\endgroup$
    – Maarten Bodewes
    Jul 19, 2017 at 22:49

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.