Using Telegram as a carrier for image steganography: Analysing Telegrams API limits

Telegram is a messaging platform with millions of users per month. For this reason, it is a possible vector for steganographic messages. We investigate the feasibility of using Telegram as a messenger service for images with steganographic content, specifically we use F5 as a proof of concept. We evaluate the optimal resolution and quality settings to achieve the highest possible payload size. In order to support longer message transfers over Telegram, we design a cover channel with a regular schedule of images to have a high bandwidth. We found that the optimal resolution for message transfers is 2560x2560 at JPEG quality settings of 82. And that this configuration allows us to send an average of 81 kilobytes of data per image.