Extract

HKDF-Extract(salt, IKM) -> PRK

Options:

• Hash- a hash function; HashLen denotes the length of the hash function output in octets

Inputs:

• salt optional salt value (a non-secret random value); if not provided, it is set to a string of HashLen zeros.

• IKM input keying material

Output:

• PRK a pseudorandom key (of HashLen octets)

The output PRK is calculated as follows:

• PRK = HMAC-Hash(salt, IKM)