HTC provides secure box to move your private text messages to it. It is protected by a password and you need to enter the password to read them, On HTC One you need to follow the instruction to boost the security of your private messages:
1. Open "Messaging" App
2. Tap on the contact or the phone number, you would like to move their messages to secure box
4. select "Move to Secure Box"
5. Select the messages to be move to the secure box
6. Hit "Move" to finish the process
** Note that if you are reading your messages stored in the secure box for the first time, you are asked to set a password.
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