—Smartphones have become an essential communication device where people share much information through this communication channel. The Android-based chat app allows users to create groups and interacts with other users by exchanging messages over a local network or Internet network. In the Android-based chat application, there are problems with data security issues. Messages sent from chat apps become insecure because the messages are on an accessible network allowing a hacker to infiltrate and steal words in data packets. Encryption becomes a good solution with the key exchange to prevent intruders or hackers trying to take data. This research proposes N-TEA algorithm as a solution in securing chat messages in Android applications. N-TEA is an encryption mechanism that works in real-time and does not depend on what data to send. This algorithm serves to support the ability of a real-time and robust encryption mechanism. The results of this study show that the change of plaintext character results in an avalanche effect of 36.72%. In another part, the change of encryption key character results in an avalanche effect of 42.9%. This research proves that the N-TEA algorithm can secure to send messages well.

Keywords—android, chatting, communication, encryption, security