BIOS mirror image offline signature method and system, terminal and storage medium

The invention provides a BIOS mirror image offline signature method and system, a terminal and a storage medium. The BIOS mirror image offline signature method comprises the steps: enabling a tool script to generate a private key by using a specified algorithm; calling a signature tool to generate a firmware key group based on the private key, and replacing a key file generated by compiling a code with the firmware key group to obtain an offline key file; signing an off-line secret key file by using the private key, and integrating a BIOS mirror image file by using the signed off-line secret key file; and signing the BIOS mirror image file by using the private key to obtain an offline signed BIOS mirror image file. The signature process is separated from the compiling process, it is guaranteed that the secret key is only exposed to necessary safety management personnel, and unnecessary potential safety hazards are avoided. Meanwhile, on the premise that a new updating tool with a verification mechanism is not