# HKDF

backport hkdf for go1.20+

export `crypto/hkdf` and `crypto/internal/fips140/hkdf` from:
https://github.com/golang/go/blob/d327e52d438854acae275cdf9d2c1fe42f037eb8/src/crypto/internal/fips140/hkdf/

https://github.com/golang/go/blob/86bbea0cfa72041fb4315eb22099b0bc83caa314/src/crypto/hkdf/