[ 源代码： python-hkdf ]
软件包：python3-hkdf（0.0.3-5）
HMAC-based Extract-and-Expand Key Derivation Function (HKDF)
This module implements the HMAC Key Derivation function, defined at http://tools.ietf.org/html/draft-krawczyk-hkdf-01
There are two interfaces: a functional interface, with separate extract and expand functions as defined in the draft RFC, and a wrapper class for these functions.