I’ve noticed that for split APK applications, ApkCombo provides a single APK file that can be directly installed. Out of curiosity, I compared the signature of the original APK from the official source with the APK downloaded from ApkCombo, and they are exactly the same. This made me wonder:
How does ApkCombo merge the split APK files without needing to re-sign them?
As far as I know, merging split APK files usually requires re-signing with a new signature, but ApkCombo seems to keep the original signature intact. Any insights into how this process works would be really appreciated. Thanks!
As Robert mentioned in the comments, this depends on certain parameters sent to Google Play when requesting the download link. Based on my research, the key parameter is Vending.version, which specifies the version of Google Play that is making the download request. The last version that can request the app without split APKs is 80913000, which represents a specific Google Play version. After this version, it’s no longer possible to download a solid APK.
Additionally, some apps have implemented restrictions within themselves, so even setting this parameter to 80913000 won't allow the app to be downloaded. You can see this in the link below, where, starting from a certain app version, even on ApkCombo, downloading a unified APK file is no longer possible:
https://apkcombo.com/space-takeover-over-city/risk.city.dominations.strategy.io.games/download/apk