How to Permanently Delete Files on Android With File Shredder

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shredderFew days ago I sold my used Samsung Galaxy S through an online portal. This one, like all the smartphones these days, had my data on its internal storage. I had to be sure that all my personal data on the internal hard disk was securely deleted and that no one could restore it using a third party recovery tool like Recuva or EaseUS.

First I thought of connecting my phone to the computer, mount its internal storage as an external drive and then use a tool like Eraser to securely delete files. But it came to me that it’s an Android I am using and there must be an app for this simple task.

And indeed, there were some and one of which seemed the most promising was the File Shredder by Lassi Marttala. File Shredder is a nifty app for Android that claims to securely delete your files on Android.

File Shredder for Android

Currently, the app does not provide any information regarding the algorithm it uses to delete the data. All it mentions is that it destroys the file by deleting it and overwrites the space with some random data. I tested the product on my Samsung Galaxy S, and indeed, all the data was erased securely and I was not able to retrieve any of it using a third-party application.

When you wish to secure delete a file on your phone, just download and install File Shredder from the Play Store and launch the application.

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The app will list all the files and folders on your smartphone. Tap the plus button next to the file or folder you want to delete (be careful here, a file once deleted cannot be recovered). After you have added all the files and folders you want to securely delete to the list, tap the shredder button that appeared on the top right corner of the app.

File Shredder for Android (1)File Shredder for Android (4)

The app will one again ask for your confirmation. After you allow the secure deletion, your phone might be irresponsive for a while depending upon the size of data you are trying to delete. My advice is not to use the phone till you see the notification of successful deletion on the notification drawer.

File Shredder for Android (3)File Shredder for Android (2)

Conclusion

After the files are deleted securely, you can hand over your phone to anyone you feel like without a wrinkle on your head for any of your sensitive data. File Shredder is there to take care of it. Do try out the app and share your experience with us.

Top Image Credit: Kai Hendry

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  • User

    I deleted all the files on my phone without the file shredder will I be able to make sure my phone is clean without being able to replace the file?

  • youslate.org

    This app is not available on Play Store now.I tried this one
    https://play.google.com/store/apps/details?id=himalaya.intellectio.fastwipe

    it was very quick reported progress in percentage and also after reboot my phone worked a bit faster .
    I am using LG Optimnus L5

  • Nathaniel Hourt

    Don’t ever trust a security app that won’t tell you exactly what it’s doing. There’s no security whatsoever in that.

    Now for the bad news: your device hasn’t been securely wiped at all. You’ve just slightly raised the bar for recovering the data. The authors of that app didn’t do their homework.

    Shredders which overwrite the file with random data work great on spinning drives, which don’t have a write limit. Phones use flash memory exclusively, however, and flash memory is made of blocks of storage which can each only be written so many times before they wear out and stop working, at which point the entire flash chip is compromised. To maximize the time before the chip dies, modern flash storage devices have a wear leveling firmware which switches out which logical blocks (which the operating system sees) correspond to which physical blocks (the actual hardware) to ensure that all blocks age at the same rate.

    What this means for file shredders is that when it overwrites the file with random data, the firmware puts that write to a different physical block, even though the OS sees it as the same logical block. That’s why you can’t read it using an off the shelf file undeleter (plus, if we’re talking internal storage, it’s an ext4 filesystem so you wouldn’t be able to easily recover the data anyways. SD cards will be FAT so undeleting is trivial and very simple tools can do it). Your data is still there, it’s just lost somewhere on the disk, but someone could absolutely read it again if they wanted to.

    The best way to securely delete on flash storage is to delete the files normally, then create huge files filled with random data until the entire storage is full. This is the best guarantee that you’ll have rewritten all of the blocks, though it’s still not 100% perfect. There are several apps available to do this.

  • intellectioworld .

    use fastwipe app on Google Play

  • bashir

    thank you so much .. i was worried about this couple of months ago now i can easily handover my cellphone to anyone. thank you :)