@classmethod
def RegisterDecrypters(cls, decrypters):
    """Registers decrypters.

    The decrypters are identified based on their lower case encryption method.

    Args:
      decrypters (list[type]): decrypter classes.

    Raises:
      KeyError: if decrypters is already set for the corresponding
          encryption method.
    """
    for decrypter in decrypters:
        cls.RegisterDecrypter(decrypter)
