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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.

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

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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.

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    $\begingroup$ It can be considered a PRNG in the same sense that AES-CTR is one. $\endgroup$
    – SEJPM
    Jul 19, 2017 at 18:33
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    $\begingroup$ 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

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