Steganographic Communication with Quantum Information

Chris Sutherland, Todd A. Brun

Quantum steganography is the study of hiding secret quantum information by encoding it into what an eavesdropper would perceive as an innocent-looking message. Here we study an explicit steganographic encoding for Alice to hide her secret message in the syndromes of an error-correcting code, so that the encoding simulates a given noisy quantum channel. We calculate achievable rates of steganographic communication over noiseless quantum channels using this encoding. We give definitions of secrecy and reliability for the communication process, and with these assumptions derive upper bounds on the amount of steganographic communication possible and show that these bounds match the communication rates achieved with our encoding. This gives a steganographic capacity for a noiseless channel emulating a given noisy channel.

Todd A. Brun

Chris Sutherland, Todd A. Brun

Characterizing secret communication over noisy quantum channels is an interesting problem from both a practical and theoretical perspective. Suppose Alice and Bob wish to communicate secret information so that an eavesdropper Eve will not suspect any type of encoded communication between the two. Classical or quantum cryptography will not suffice since it is always clear secret communication is taking place. Therefore Alice and Bob must execute what is known as a quantum steganographic protocol. Assuming Eve only has partial knowledge of the channel connecting Alice and Bob, we show that for the bit-flip and depolarizing channels Alice can use Eve's lack of knowledge of the channel parameter to encode quantum information steganographically. We give an explicit encoding procedure and calculate the rate at which Alice and Bob can communicate secretly. We also show that our encoding is optimal for nondegenerate quantum codes. We calculate the rate at which a secret key must be consumed. Finally, we discuss the possibility of steganographic communication over more general quantum channels and conjecture a general formula for the steganographic rate.

Lin Liu, Guangming Tang, Yifeng Sun +1 more

David S. Simon, Gregg S. Jaeger, Alexander V. Sergienko

Gabriela Mogos

Steganography is the art and science of hiding the fact that communication is taking place. Steganographic systems can hide messages inside of images or other digital objects. To a casual observer inspecting these images, the messages are invisible. The security of a classical steganographic system relies on the secrecy of the encoding system. Once the encoding system is known, the steganographic system is defeated. However, modern steganography should be detectable only if secret information is known, namely, asecret key. Because of their invasive nature, steganographic systems leave detectable traces within a medium's characteristics. This allows an eavesdropper to detect modified media, revealing that secret communication is taking place. Although the secret content is not exposed, its existence is revealed, which defeats the mainpurpose of steganography. This work has as purpose to expand the field of applicability of the steganography from the classical informatics to the quantum one.