"crypto/internal/fips140/hmac" ) func Extract[H fips140.Hash](h func() H, secret, salt []byte) []byte { if len(secret) < 112/8 { fips140.RecordNonApproved() } if salt == nil { salt = make([]byte, h().Size()) } extractor := hmac.New(h, salt) hmac.MarkAsUsedInKDF(extractor) extractor.Write(secret) return extractor.Sum(nil) } func Expand[H fips140.Hash](h func() H, pseudorandomKey []byte, info string, keyLen int) []byte { out := make([]byte, 0, keyLen) expander := hmac.New(h, pseudorandomKey) hmac.MarkAsUsedInKDF(expander)...