docs: def getCiphertextLen(self, ciphertext):
          """Given a ``ciphertext`` with a valid header, returns the length of the ciphertext inclusive of ciphertext expansion.
          """
  
          plaintext_length = self.getPlaintextLen(ciphertext)
          ciphertext_length = plaintext_length + Encrypter._CTXT_EXPANSION
          return ciphertext_length