Table 4.

Attack descriptions.

Attack Type	Description
Consensus mechanism challenge	Whether the consensus algorithm between the parallel blockchain and the main chain can achieve real security.
Witch attack	A malicious node illegally presents multiple identities to the outside world and conducts malicious behaviors after mastering multiple nodes.
Data leakage risk	When data is transmitted between the parallel blockchain and the main chain, malicious nodes attack, resulting in the leakage of data information.
Data tampering risk	In the cross-chain process, malicious nodes attack and tamper with the data during data transmission, resulting in untrustworthy data.
Data loss risk	In the cross-chain process, data is “dropped out”, resulting in data loss.