Direction{[]byte{'A'}, []byte{'C'}, []byte{'E'}} } func Keys[Hash fips140.Hash](hash func() Hash, d Direction, K, H, sessionID []byte, ivKeyLen, keyLen, macKeyLen int, ) (ivKey, key, macKey []byte) { h := hash() generateKeyMaterial := func(tag []byte, length int) []byte { var key []byte for len(key) < length { h.Reset() h.Write(K) h.Write(H) if len(key) == 0 { h.Write(tag) h.Write(sessionID) } else { h.Write(key) } key = h.Sum(key) } return key[:length] } ivKey = generateKeyMaterial(d.ivTag, ivKeyLen)...