The function of Android’s .asec file

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How does this file work? Can it be used to retrieve old data from the app when the phone’s no longer functioning/accessible? For example, if there were notes/texts saved locally in the app, would it be stored in the .asec file?

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Anonymous 0 Comments

These are files that are created when an Android application is installed on a removable SD-card. The file is encrypted using a key that is stored in the non-removable memory of device that performed the installation and is thus not useable if that original device is lost or broken.

Why is this done?

Normally, to acess data on an Android device the device first has to be unlocked by the user because the entire system is usually encrypted by default. With a removable SD-card one might want to remove the card from the device and put in another that can read the contents, say to transfer photos and the like, so the entire SD card cannot be encrypted. To prevent applications that are installed on the SD-card from being modified by malicious actors when the card is removed and compromising the system when the card is returned, secure application data, including the application code itself, is stored in an encrypted format, with the encryption key tied to the Android system where the application was installed and stored in the encrypted non-removable memory of that system.