How to Encrypt and Decrypt Files on an Android Device

Encrypting files on your Android device allows you to keep those files from being stolen, and even if they get stolen they would be unreadable as long as they are not decrypted using a proper key. What it does is present the file as garbled information, usually to an AES 128 or AES 256 standard that essentially makes the information impossible to decipher.

Here’s how to encrypt files on your Android device – whether you want to encrypt everything on your phone or just specified files.

The most comprehensive encryption method on Android is to do a full-disk encryption, which is a feature that’s handily baked into the operating system. This will lock your Android device behind a password and/or PIN and on weaker devices may cause some slowdown. The price you pay for security!

To do this, go to “Settings -> Security -> Encrypt phone.”

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If you’re on Android 7.0 or higher, then you might find that this option isn’t there. An alternative location for this is “Settings -> Storage -> Phone storage encryption.”

Still, a third possibility is that you need to unlock developer options to encrypt your phone. To turn it on you’ll need to go to “Settings -> About -> Software information -> More,” then tap “Build number” seven times to unlock Developer options.

Under “Settings -> Developer” options you should now find the option to “Convert to file encryption.” Back up your data, though, because this will erase everything on your device and start fresh.

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In order to encrypt files on your device you are going to use an app called Andrognito that uses the 256-bit encryption algorithm to securely safeguard your files.

1. Head over to the Google Play store and download and install Andrognito on your device.

2. Launch the app.

3. When the app is launched for the first time you need to enter your name and a four-digit PIN that will safeguard your files. Do so and tap on the arrow to move forward.

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4. Enter the four-digit PIN again to confirm it. Tap on the arrow icon to move forward.

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5. For an extra layer of security it will ask you to create a security question. Type in the question and answer, and tap on the arrow icon to move ahead.

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6. Here comes the part where you can create a vault to put your encrypted files in. Type in a name for the vault and a four-digit PIN. Tap on the pink icon, and you will move to the next screen.

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7. You can now start adding files to the vault for encryption. Tap on the “+” icon on your screen and select either All Files, Images, or Videos to be encrypted.

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8. Tap and hold on a file for the encryption option to show up. You can select multiple files to be encrypted all at once. When you are done selecting, tap on the lock icon given in the top-right corner to encrypt the selected files.

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9. You should see the following orange icon on your screen when the files are successfully encrypted.

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The selected files have been encrypted using a military-grade AES 256-bit encryption algorithm. If someone gets access to these files, they will not be able to read them unless they have the key that was used to encrypt the files.

If you wish to decrypt the files, you can do so using the same app.

1. Launch the Andrognito 2 app from your app drawer.

2. Enter your four-digit PIN to access the safeguarded data.

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3. You should be able to see all the files that you have encrypted so far. Tap and hold on the ones you wish to decrypt, then tap on the unlock icon given in the top-right corner. It should decrypt the selected files for you.

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Your files are now decrypted, and they are no longer a part of your vault. They can now be accessed as normal files just like you were accessing them before.

While locking a file allows you to have an additional layer before someone can access your files, encrypting provides more protection, as it hides them behind an unbreakable code of nonsense. If you’d like to keep your files private, this is the best way to ensure that the only people to ever seen them will be the people you want to see them.

This article was first published in May 2015 and was updated in Nov 2017.

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