code: def public_decrypt(pub, message):
      '''
      Verify an M2Crypto-compatible signature
  
      :param Crypto.PublicKey.RSA._RSAobj key: The RSA public key object
      :param str message: The signed message to verify
      :rtype: str
      :return: The message (or digest) recovered from the signature, or an
          empty string if the verification failed
      '''
      if HAS_M2:
          return pub.public_decrypt(message, salt.utils.rsax931.RSA_X931_PADDING)
      else:
          verifier = salt.utils.rsax931.RSAX931Verifier(pub.exportKey('PEM'))
          return verifier.verify(messagef public_decrypt(pub, message):
      '''
      Verify an M2Crypto-compatible signature
  
      :param Crypto.PublicKey.RSA._RSAobj key: The RSA public key object
      :param str message: The signed message to verify
      :rtype: str
      :return: The message (or digest) recovered from the signature, or an
          empty string if the verification failed
      '''
      if HAS_M2:
          return pub.public_decrypt(message, salt.utils.rsax931.RSA_X931_PADDING)
      else:
          verifier = salt.utils.rsax931.RSAX931Verifier(pub.exportKey('PEM'))
          return verifier.verify(message)
docs: Verify an M2Crypto-compatible signature
  
      :param Crypto.PublicKey.RSA._RSAobj key: The RSA public key object
      :param str message: The signed message to verify
      :rtype: str
      :return: The message (or digest) recovered from the signature, or an
          empty string if the verification failed