code: func IsPKCS8(derBytes []byte) bool {
  	if _, err := x509.ParsePKCS8PrivateKey(derBytes); err == nil {
  		return true
  	}
  
  	return pkcs8.IsEncryptedPEMBlock(&pem.Block{
  		Type:    "PRIVATE KEY",
  		Headers: nil,
  		Bytes:   derBytes,
  	})
  }
docs: // IsPKCS8 returns true if the provided der bytes is encrypted/unencrypted PKCS#8 key