Can you set a password just for SMS messages on an iPhone 4s?

I work in a lab where we can play music and so I plug it in and walk away. I want to be able to walk away knowing that no one at work can look at my private life.

1) Tap Settings.
2) Choose Pass code Lock form the right side menu.
3) Tap turn Pass code on.
4) Enter a 4 digit Pass code that you will remember, but not something as simple as 1234. For help, use the letters to spell out a four letter word.
5 )Enter the Pass code a second time to verify.

You will need to check the erase data box if you want the phone to wipe after 10 failed attempts. This can add security, but I do not check this box. You can use Find My iPhone to do this, and too often I hear of pranks that involve entering the wrong Passcode too many times to cause data loss.

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