If the application doesn't use code signing, the better and more popular your software is, the more likely it is to be illegally packaged with other software, thus harming the interests of software vendors and users. For some free trial software, if you join code signing, any attempt to illegally modify the software code and bypass the free trial period will fail to pass the signature verification, thus protecting the rights and interests of software manufacturers.
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Why does software need a digital signature?