salt = make([]byte, h().Size()) } extractor := hmac.New(h, salt) hmac.MarkAsUsedInKDF(extractor) extractor.Write(secret) return extractor.Sum(nil) } func Expand[H hash.Hash](h func() H, pseudorandomKey []byte, info string, keyLen int) []byte { out := make([]byte, 0, keyLen) expander := hmac.New(h, pseudorandomKey) hmac.MarkAsUsedInKDF(expander) var counter uint8 var buf []byte for len(out) < keyLen { counter++ if counter == 0 { panic("hkdf: counter overflow") } if counter > 1 { expander.Reset() }...