翻译为英文：增加了v2签名校验的功能实现方式与v1类似。现在的--signature-check将会同时检测v1与v2签名校验文件分别在assets目录下的PK与PK2

Added functionality for v2 signature verification, implemented similar to v1. Now, the --signature-check will check both v1 and v2 signatures. The verification files are located in the assets directory under PK and PK2, respectively.