Data security is one of the major challenges that prevents the wider acceptance of mobile devices, especially within business and government environments. It is non-trivial to protect private and sensitive data stored in these devices due to the limited resources and computing power, particularly when they fall in the hand of an adversary. Previously Chen and Ku proposed a lightweight data encryption and storage scheme named Self-Encryption (SE) to meet the challenge. However, our recent research revealed that there are critical weaknesses in SE. This paper presents the detailed analysis of the weaknesses of SE scheme and proposes a solution to remove the flaws in SE. Through real-world measurements on top of the iPhone platform, we verified the effectiveness of our proposal.