11 alleged Russian spies have been arrested and charged with conspiracy to commit an offense against the United States by not registering with the attorney general. 9 of these individuals have also been charged with money laundering. Details on the people arrested are here. One couple is based in Cambridge, MA.
The FBI says that these spies not only used encryption to protect data on their laptops and USB flash drives, but that they also are suspected of using proprietary Russian-build steganography software to hide data inside images and other files on their computers.
Steganography is the technique of hiding information inside other documents or data, so that it cannot be detected. Combining steganography with cryptography can create systems of communications and data protection that are incredibly difficult to detect and to crack.
For example, imagine encrypting a data file using strong encryption, and then inserting that file as noise in the soundtrack or video stream of a large .wmv video file. Then posting that file to a website or sharing it on a bittorrent network for its intended recipients to download. If you communicate out-of-band (through an email or a phone call or SMS) to your recipients the name of the video file, and if there is a key sharing protocol (ie. they know the password to decrypt the data), then its highly likely that only that person will be able to know that the encrypted data is there, and be able to decrypt it.
If anyone else downloads the file, even using steganographic detection tools they are unlikely to detect the encrypted data. And even if they were able to extract it, they would still have to crack the encryption.
In fact, one wishing to communicate covertly would want other people to download the file, so that nobody monitoring networks can tell who the file is intended for.
In the case we are discussing today, the alleged Russian spies were detected sending data to known addresses of Russian government computers (we assume IP addresses). Using the technique I discuss, they would have been able to avoid such detection.
One other thing I found interesting about this article is that a 27 character password was required to access the steganographic data. Sounds like a great security measure to have such a long password. However, the agent wrote the password down on a piece of paper! In such a case, it would have been much more secure to use a shorter password that was more easily remembered.