Steganography of Hypertext Transfer Protocol Version 2 (HTTP/2)

Network steganography consists of different steganographic technics that utilize network protocols for hiding data. We present nine new covert channels which utilize the new standard, HTTP/2, and which can be used regardless its transport carrier (TLS or clear TCP). These covert channels use a protocol feature that has dual nature (for example, no padding can be represented in two ways); or a feature that is not mandatory (as streams prioritization and dependencies); or random value field (as PING frame payload field); or there is no strict rule how to obtain new values for some fields (as stream identifiers). As far as we know, this is the first research about hiding data in HTTP/2. Also, we give a small survey of existing covert channels that can be created using HTTP/1.x, with the analysis do they work or not work with the HTTP/2