The widespread use of encryption by criminals - long feared by intelligence and law enforcement agencies - has yet to materialise, according to the man in charge of the country's largest digital forensics unit.
Mark Stokes, head of the Metropolitan Police's Digital and Electronic Forensic Services (DEFS), told The Register that "literally a handful" of the tens of thousands of devices it handles each year from across the whole of London involve encrypted data.
"We're still to this day not seeing widespread use of encryption," he said.
Despite the availability of scrambling products such as PGP, TrueCrypt and Microsoft's BitLocker, criminals are not making life difficult for forensic investigators to access their files.
"You'd think paedophiles would use it, but they don't. It's just human nature to think they'll never get caught," said Stokes, an electronics engineer who uses TrueCrypt on his own home computer.
"I think it's just not easy to use. You've got to keep the password, people forget their passwords, and generally human beings are lazy and they can't be bothered with it," he said.
"In the next five to 10 years as computers become faster and easier to use potentially it could become a problem, and that's something we have to keep our eye on."
Stokes said that often there are forensic signs suspects have toyed with encryption, but not bothered to apply it to their systems.
On the rare occasions frontline police hand DFES encrypted kit, it carries out simple dictionary attacks in an attempt to guess the passphrases. When a more exotic mathematical approach is required, the work is outsourced to the supercomputers at GCHQ's National Technical Assistance Centre.
Fears by authorities that mainstream take-up of encryption would hamper terrorism and serious crime investigations persuaded the government to introduce Part III of the Regulation of Investigatory Powers Act (RIPA) in 2007. It grants investigators powers to demand passphrases from suspects, with the threat of up to five years' jail if they refuse or remain silent.
Last week we revealed that the first person known to be sentenced under RIPA Part III was a schizophrenic with no previous criminal record, who was arrested by counter-terrorism police after a model rocket was detected in his luggage. ®