When criminals turn to disk encryption to hide the evidence of their crimes, law enforcement investigations can hit a brick wall. Where digital forensics software has failed to recover encryption passwords, one tried and true technique remains: violence.
Updated Jan 27 2009 with a comment from the Turkish Government. See below
When criminals turn to disk encryption to hide the evidence of their crimes, law enforcement investigations can hit a brick wall. Where digital forensics software has failed to recover encryption passwords, one tried and true technique remains: violence. It is is this more aggressive form of
good cop bad cop behavior which the Turkish government is alleged to have turned to, in order to learn the cryptographic keys of one of primary ringleaders in the TJ Maxx credit card theft investigation.
The 2005 theft of tens of million credit card numbers from an unsecured wireless network run by TJ Maxx stores has lead to over 150 million dollars in damages for the company. The two gentlemen behind the heist sold the pilfered credit card information to others online. Eventually, the stolen cards reached Maksym Yastremskiy, a Ukrainian citizen, and, according to media reports, a "major figure in the international sale of stolen credit card information."
Mr Yastremskiy was later arrested in 2007, while on vacation in Turkey. The US government has formally requested that Yastremskiy be extradited, and has charged him with a number of crimes including aggravated identity theft.
According to comments allegedly made by Howard Cox, a US Department of Justice official in a closed-door meeting last week, after being frustrated with the disk encryption employed by Yastremskiy, Turkish law enforcement may have resorted to physical violence to force the password out of the Ukrainian suspect.
Mr Cox's revelation came in the context of a joke made during his speech. While the exact words were not recorded, multiple sources have verified that Cox quipped about leaving a stubborn suspect alone with Turkish police for a week as a way to get them to voluntarily reveal their password. The specifics of the interrogation techniques were not revealed, but all four people I spoke to stated that it was clear that physical coercion was the implied method.
The Turkish interrogation seemed to have worked as Mr Cox was even able to share Yastremskiy's encryption password with the audience.
Mr Cox, the Assistant Deputy Chief for the DOJ's Computer Crime and Intellectual Property Section, made the comments during his keynote talk at an invitation only event for academic and industry experts focused on phishing related crimes. This blogger has spoken to four sources, each in independent interviews, who claim to have witnessed Mr. Cox making such statements. However, due to the closed-door nature of the event, and fearing that coming forward publicly would lead to them being blackballed from future information sharing sessions, no one would go on the record to make their claims.
If Mr Yastremskiy is successfully extradited to the United States, it is unclear if the evidence from his encrypted disk could be used against him in court. It also remains an open question as to how much the US knew about the alleged beating of Yastremskiy by the Turkish authorities, and when.
If Mr Cox's alleged comments are indeed true, this is alarming news. The majority of cryptographic tools in use today are designed around the general assumption that an end-user can refuse to disclose his or her key if the computer is seized. While password discovery via torture is something that has been discussed in the academic literature for a number of years (it is commonly known as rubber-hose cryptanalysis), it has for the most part remained a theoretical threat. A few tools, such as TrueCrypt, are designed to resist such attacks, and thus use deniable encryption -- that is, making it impossible for someone to examine a computer and be able to determine if there is anything encrypted on the disk. Some tools even allow for multiple deniable encrypted folders, each with a different password.
Of course, Truecrypt and other tools that have adopted deniable cryptography do not stop government agents from torturing a suspect. It just means that they cannot be sure when to stop the beatings, as there could always be one additional hidden file on the disk.
Multiple requests for comment, by both phone and email to Howard Cox and the DOJ Office of Public Affairs have been ignored. Similarly, the Turkish embassy in Washington DC had not responded to a request for comment by press time.
A Freedom of Information Act request has been submitted for the slides and notes for Mr Cox's speech, however, this could take months or years before any information is returned.
Update:On January 27, 2009, Berkan Pazarcı, the First Secretary at the Turkish Embassy in Washington DC replied to the request for a comment that I sent back in October of 2008:
The Turkish Ministry of Justice informed the Embassy that Maksym Yastremskiy has not filed any complaint for being subject to ill-treatment or police violence or brutality. The medical reports issued by the Turkish forensic medicine clearly state that no signs of physical harm have been detected on his body.
Mr Cox presented at a closed-door session at the Anti-Phishing Working Group e-Crime summit. I presented at the same conference the next day, at a session open to the general public. My hotel and airplane ticket were paid for by the APWG, as part of a scholarship program for graduate students.
In 2006, the FBI investigated me for some of my research into boarding pass security. While no charges were ever filed, it's reasonable to state that I have little affection for the DOJ computer crimes section.
Finally, due to the fact that the Turkish government is involved, it is worth mentioning that I am 50% Armenian by blood. Several generations ago, a number of my family members died at the hands of the Ottoman Empire (now Turkey). I do not have an axe to grind in this area, but in the interest of honest disclosure, I thought it should be mentioned here.