The st UTS-VNU Research School Advanced Technologies for IoT Applications Hidden data inside plain sight PNG covert by a multiple platform chat sharing application NGUYEN TRI DUC - Ho Chi Minh City University of Technology Problem statesment - Alice and Bob want to send a message to each other They are certainly sure that Eve always eavesdropping their network traffic and hijacking their devices They need a covert channel which is a type of an application encrypting and hiding the secret and also erases its memory on the fly once it is terminated Abstract One year after the Snowden Leaks, we are unaware that we were under mass-surveillance from government or 3rd party organizations In addition, mobile devices were vulnerable to many threats at the moment In late 2014, there is no such chat application making use of Steganography to conceal a secret message in a plain sight The outcome application is a combination between secret algorithms in Steganography and a hard problem in Cryptography aiming to provide a user the most secure way to share the secret on a mobile platform Thanks for the outstanding of Kivy Frameworks; the application works on both iOS and Android Contributions - Because of the discrete log problem in RSA and advantages of AES, a difficulty of decrypting the encrypted message is guaranteed - The secret algorithm performing Steganography can embed the encrypted data into any PNG image file formats; the eavesdropper will consider the image file as a part of the normal conversation because the image file before applying the secret algorithm is visually the same as the one after - Although the application gets broken down by reverse engineering, the attacker must solve the aforementioned hard problems in both RSA and AES, and also must reveal the multiple times hashed common key which Bob and Alice share before starting their conversation Features - The application works both on Android and iOS - The original image is deleted immediately after being sent, which prevents detecting the differences between the original and the embedded pixel in a PNG image The memory is initialized immediately after the cryptographic phase, which prevents itself from getting analyzed by a forensic approach - The PNG image will be removed as soon as the conversation participants check it - No files are stored on the disk Also no messages are preserved in the runtime memory 000 111 001 110 010 011 Normal Pixel Controller Embedded Pixel 110 101 100 References [1] Luis von Ahn and Nicholas J Hopper Public-Key Steganography Submitted to crypto 2003 [2] Ross J Anderson and Fabien A P Petitcolas On The Limits of Steganography IEEE Journal of Selected Areas in Communications, 16(4) May 1998