Many Nexus 7 owners aren't aware that there are actually several different 'levels' of security you can have on your tablet to keep the information on it safe from prying eyes. These range from simply having no passcode, in which you simply swipe the ring to get to the home page to pin codes consisting of only numbers or passwords that can contain a mixture of both numbers and letters of a length of your choosing. For most casual tablet users, one of these options should suffice.
But what if you're working in a corporate atmosphere or if you have valuable or proprietary information on your Nexus 7 and you want to make sure that in case of a lost tablet, that the information can't fall into someone else's hands. Well for these Nexus 7 owners in search of that top level of security there is an 'encryption' option for the Nexus 7 that will 'encrypt' all the data and files on your tablet including Google Accounts, app data, music and other media, downloaded information, and so on, making it virtually impossible for someone to get any usable information off of your stolen or lost Nexus 7 Tablet.
Now this encryption process does take some time to complete. There's several steps involved and it can take an hour or more for your tablet to go through the process of encrypting all its data. Also, should you lose your passcode and not be able to get into your device the only way to un-encrypt it is to do a factory reset...which will erase all your data. For this reason it is extra, extra important that you write your passcode down somewhere so that you won't have to worry about that.
Ok, so here's how you encrypt the data on your Nexus 7 straight from Google's page which is linked below.
Warning: Encryption is irreversible. The only way to revert to an unencrypted tablet is to perform a factory data reset, which erases all your data.
Before turning on encryption, prepare as follows:
1. Set a lock screen PIN or password.
2. Charge the battery.
3. Plug in your tablet.
4. Schedule an hour or more for the encryption process: you must not interrupt it or you will lose some or all of your data.
When you're ready to turn on encryption:
1.Touch Settings > Personal > Security > Encryption > Encrypt tablet.
2. Read the information about encryption carefully.
The Encrypt tablet button is dimmed if your battery's not charged or your tablet's not plugged in. If you change your mind about encrypting your tablet, touch the Back button.
Warning: If you interrupt the encryption process, you will lose data.
3. Touch Encrypt tablet.
4. Enter your lock screen PIN or password and touch Continue.
5. Touch Encrypt tablet again.
The encryption process starts and displays its progress. Encryption can take an hour or more, during which time your tablet may restart several times.
When encryption is complete, you’re prompted to enter your PIN or password.
Subsequently, you must enter your PIN or password each time you power on your tablet, to decrypt it.