Key Derivation Function (KDF)

#Cryptography #KDF
A Key Derivation Function (KDF) is a function that takes some source of initial keying material and uses it to derive one or more cryptographically strong keys. This specification uses a KDF with the following API and parameters:

• Extract(salt, ikm): Extract a pseudorandom key of fixed length Nx bytes from input keying material ikm and an optional byte string salt.
• Expand(prk, info, L): Expand a pseudorandom key prk using the optional string info into L bytes of output keying material.
• Nx: The output size of the Extract() function in bytes.