Demystifying Code Signing
summary
Demonstrates using APK Signer to sign and resign an APK, unzipping the APK to show META-INF/manifest.mf contains SHA‑256 hashes of every file, and reinstalling fails when signatures differ because Android blocks updates with a different key. Explains Play App Signing: Google re‑signs AAB‑derived APKs with a Play key and treats the developer key as an upload key. Concludes signing protects the OS and ownership, not secrets, and recommends obfuscation, runtime checks, binary integrity and whitebox cryptography (Pace).
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chapters (17)
- 0:00Code signing on Android
- 1:30What code signing is
- 2:33Signing an APK demo
- 5:06How APK signing works
- 7:14Why resigning fails
- 9:11Code signing for ownership
- 11:48Signing for interoperability
- 13:11Android Studio signing
- 13:56APKs vs App Bundles
- 14:17Classic signing flow
- 14:38Play App Signing changes
- 16:43Risks of Play certificates
- 17:27App Bundles with Play Signing
- 18:29Signing security limits
- 19:12Reverse engineering APK demo
- 20:15Beyond code signing
- 21:22Summary
