Google introduced full-device encryption back in Android Gingerbread (2.3.x), but it has undergone some dramatic changes since then. On some higher-end handsets running Lollipop (5.x) and higher, it’s enabled out-of-the-box, while on some older or lower-end devices, you have to turn it on yourself.
Android uses dm-crypt encryption function, which is the standard disk encryption system in the Linux kernel. It’s the same technology used by a variety of Linux distributions.
Encrypting the device can take an hour or longer. Your device’s battery must be at least 80% charged. Android won’t even start the process otherwise. Your device must be plugged in throughout the entire process. Again, if you’re rooted, be sure to unroot your phone before continuing. And one more thing if you interfere with the process or end it before it’s finished, you will likely lose all your data. Once the process is started, it’s best to just leave the device alone and let it do its thing.
So learn how to encrypt Android devices :
First go to “Settings“.
Now tap on “Security“. If your phone is already encrypted it will display it here.
If the device isn’t encrypted, you can start the process by tapping the “Encrypt phone” option.
In the next screen you will see a warning to let you know what to expect once the process is finished. If you’re ready to proceed, hit the “Encrypt phone” button.
Again one more warning will popup, which tells you not to interrupt the process. If you’re still not scared away, one more tap of the “Encrypt phone” button to stat the process.
Now your phone will reboot and start the encryption process. A progress bar and estimated time till completion will show up.
Once it’s finished, the phone will reboot and you’re back in business. If you set up a lock screen password, PIN, or pattern, you’ll have to put it in now so the device will finish the boot process.
If you haven’t set up a PIN or password, now is a good time to do so. Head into your device’s “Settings > Security” menu. From there, select the “Screen Lock” option.
To confirm if encryption is enabled head to “Settings > Security” and you can see confirmation “Encrypted” under “Encrypt phone” option.
So that’s it all your personal stuff in your Android device is safe. Usually encryption will only applied to the data stored in your phone memory. Still the hacker can access your SD card by inserting it to other phone or by card reader.
Don’t panic, luckily you also can encrypt your SD card to keep data safe and prevent the card from being used in another device (unless wiped first).
For that Head to “Settings“, select “Security“, followed by “Encrypt external SD card” and click “Enable“.