The secure deletion problem on Android
Our smart phones store sensitive personal and business data such as emails, SMS messages, pictures, and our web browsing histories. Unfortunately deletion on phones is not immediate. Even after you delete your email or clear your browser's cache, the data will remain on your phone typically for days or even months, depending on phone usage. This data is easily recoverable with minimal effort by technically-knowledgable persons.
Standard countermeasures do not help, such as overwriting files with random data, due to special features of the Android's file system (namely the use of journaling). Even encryption does not help as the associated key must be stored temporarily in memory and is recoverable after deletion.
Our SDAndroid application solves this problem. SDAndroid forces your Android phone to overwrite the sections of storage where deleted data resides so that the data is really deleted and cannot be recovered.
The application is currently available from the Android Market. After installation you can directly securely delete your data. You can also set up automatic deletion of erased data at regular intervals: a background process will take care of that.
A nontechnical overview video describing the problem is available (German, around minute 8.15) SF.TV