# 4.5 Blacklist Management

To ensure the security of transactions, DxChain will manage the blacklist addresses through both EVM bottom layer and system built-in contract: the system built-in contract provides a blacklist management mechanism, and the EVM bottom layer verifies internal contract transactions.

The verification process for each transaction is as follows:

1\. When the transaction is packaged and executed, sender and receiver’s address will be checked first to see whether the address is legal (for example, whether it is a hacker address or be hacked). If the address is illegal, the transaction will not be executed.

2\. When the transaction is executed in the EVM, check whether the internal contract address is legal.

![Figure 7: Blacklist Verification](https://402733873-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Ft7Yq0wZVG1pJ3PiTzoaE%2Fuploads%2FUaQjDw90H528cqVfMrJM%2F%E8%8B%B1%E6%96%875.png?alt=media\&token=8028cbbf-bd23-4e1d-8bcf-60caf4c72635)

After two-layer mechanisms screening, any transaction containing a blacklisted address will be accurately intercepted to protect the user's asset security.

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*`The blacklist addresses are mainly added from users' reports or other hack incidents.`*
