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Questions tagged [hkdf]

HKDF is a key derivation function specified in RFC5869.

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Orignal Krawczyk's HKDF vs latest NIST SP800-56C

I've noticed that the original HKDF in rfc5869 defines a feedback loop. So the pseudo-code is something like: ...
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Why would one split HKDF output into multiple parts instead of expanding it multiple times

Reading the implementation details of Signal's approach on double ratchet algorithm I noticed the following key derivation procedure for using AES-CBC with HMAC: HKDF is used (...) to generate 80 ...
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Combining multiple hash functions for HKDF

I'm trying to apply the hash function combination method described in https://eprint.iacr.org/2013/210.pdf to a HKDF PRNG construction. Thing is it needs 4 uniformly random parameters/keys chosen by ...
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Why derive keys from a master key instead of generating random keys?

I noticed AWS KMS generates encryption keys based off of a master key, using a key derivation function (HKDF). What's the practical advantage of deriving keys based on a master key? Isn't it simpler ...
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Which 'info' and 'salt' parameters to use in HKDF for TLS 1.3?

all the following discussion is for HKDF in TLS1.3: Regarding the 'salt' parameter in - HKDF-Extract(salt, IKM) as written in RFC 5869: HKDF without having to protect the secrecy of the salt. In ...
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How to envision entropy concentration in HKDF “extract” stage?

RFC 5869: Thus, the goal of the "extract" stage is to "concentrate" the possibly dispersed entropy of the input keying material into a short, but cryptographically strong, pseudorandom key. The ...
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Question on inputs of PRFs and HKDF KDF

I've read a lot of information about PRNGs, PRFs and KDFs. As far as I know: PRNG: The seed for the PRNG must be a uniform string. It transforms a short real uniform string into some bits of pseudo-...
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HKDF to derive multiple keys from a strong constant master secret and a weaker changing secret

I am working with constrained nodes (type OpenMote CC2538) on a (constrained) 6TiSCH network and I am trying to design a good re-keying scheme designed to generate AES-128 keys dubbed Device ...
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Is it safe to re-use the salt for HKDF as a challenge for proof of possession after key derivation?

I have a system made of 2 or more parties, already sharing a master key MK, who want to agree on a session key SK (both 128-bit ...
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Random numbers for Master Key and Key_block

Exploration through RFCs concludes that random numbers used in the creation of Master Key and Key Block(Key material for Encryption Key and Mac Secret) are from ServerHello.random and ClientHello....