The 33-year-old man, originally from London, is currently held at a secure mental health unit after being sectioned while serving his sentence at Winchester Prison.

In June the man, JFL, who spoke on condition we do not publish his full name, was sentenced to nine months imprisonment under Part III of the Regulation of Investigatory Powers Act (RIPA). The powers came into force at the beginning of October 2007.

JFL told The Register he had scrambled the data on several devices as part of security measures for his business, a small software company.

He was arrested on 15 September 2008 by officers from the Metropolitan Police's elite Counter-Terrorism Command (CTC), when entering the UK from France. Sniffer dogs at Gare du Nord in Paris detected his Estes model rocket, which was still in its packaging and did not have an engine.

On arrival at St Pancras, JFL was detained under the Terrorism Act and taken to Paddington Green police station, a highly secure facility where UK police hold their most dangerous suspects.

He was returning to the UK for an appointment with customs officials, to surrender after a missed bail appearance. This separate customs investigation - since dropped without charges - surrounded a failed attempt to enter Canada, and JFL missed bail following a move to the Netherlands. This contact with British authorities was apparently part of CTC's decision to arrest JFL.

While interviewing him, CTC, the unit that in 2006 replaced Special Branch as the UK's national counter-terror police, also seized more luggage. JFL had sent packages separately via Fedex to the Camden Lock Holiday Inn, where he had booked a room.

Throughout several hours of questioning, JFL maintained silence. With a deep-seated wariness of authorities, he did not trust his interviewers. He also claims a belief in the right to silence - a belief which would later allow him to be prosecuted under RIPA Part III.

A full forensic examination found nine nanograms of the high explosive RDX on his left hand, but JFL was given police bail. His passport was seized, however.

JFL says he does not know how the RDX, which has has military and civil applications, came to be on his hand. A result of five nanograms or less is routinely discounted by forensics and no charges were ever brought over his result of nine nanograms.

He returned to Paddington Green station as appointed on 2 December, and was re-arrested for carrying a pocket knife. During the interview CTC officers told JFL they wanted to examine the encrypted contents of the several hard drives and USB thumb drives they had seized from his Fedex packages.

Again he maintained silence. Police then warned him they would seek a section 49 notice under RIPA Part III, which gives a suspect a time limit to supply encryption keys or make target data intelligible. Failure to comply is an offence under section 53 of the same Part of the Act and carries a sentence of up to two years imprisonment, and up to five years imprisonment in an investigation concerning national security.

Following the warning he was bailed again, to reappear on 4 February.

JFL did not attend the bail date. Instead he moved to Southampton, living in a series of temporary homes. He says he felt harassed by authority and helpless against police he believed were determined to pin a crime on him.

His disappearance led to a raid on 7 March this year. Officers bearing sub-machine guns broke down the door of JFL's flat. He rang local police before realising CTC had come for him.

At the local Fareham police station he was served with the section 49 notice. Signed by CTC's Superintendent Bell, it said: "I hereby require you to disclose a key or any supporting evidence to make the information intelligible."

JFL maintained his silence throughout the one hour time limit imposed by the notice. He was charged with ten offences under section 53 of RIPA Part III, reflecting the multiple passphrases needed to decrypt his various implementations of PGP Whole Disk Encryption and PGP containers.

The list had been compiled by the National Technical Assistance Centre (NTAC), part of the intelligence agency GCHQ, which attempts to decipher encrypted files for intelligence and law enforcement agencies.

In his final police interview, CTC officers suggested JFL's refusal to decrypt the files or give them his keys would lead to suspicion he was a terrorist or paedophile.

"There could be child pornography, there could be bomb-making recipes," said one detective.

"Unless you tell us we're never gonna know... What is anybody gonna think?"

JFL says he maintained his silence because of "the principle - as simple as that"

He was also charged for his February missed bail appearance and for two attempts to get a new passport falsely claiming his was lost. He says CTC told him he would not get the one they had seized back, so he applied for a new one.

After three months on remand JFL faced trial on 2 June. He pleaded guilty to all the charges, wrongly believing he would be released that day with an electronic tag thanks to time served. Instead, taking into account the passport offences and missed bail, he received a total of 13 months.

Before finishing what would have been a six-and-a-half-month prison term during September, JFL was sectioned under the Mental Health Act. He now does not know when he will be released from hospital.

In his judgment, Judge Hetherington accepted JFL was no threat to national security and noted his outsider lifestyle. "You... wished to involve yourself in a world which was largely based upon the access to the internet and using computers and not really interacting with other people in the ordinary outside world to any great extent," he said.

"It is said on your behalf that you lead an existence rather akin to that of a monk, and that there is nothing sinister in any of this but it is essentially private matters and you do not see why you should have to disclose anything to the authorities."

The judgment also took note of JFL's unusual hobbies and interests. He describes himself as an "amateur scientist" and his Fedex packages contained lab equipment, putty, devil bangers (which explode with a snap when thrown to the ground and are sold in joke shops), a metal detector and body armour. He also had a book on gun manufacture, a book on methamphetamine production and an encryption textbook. All are available from Amazon.

JFL also had a copy of Steal This Book, Abbie Hoffman's 1970s counter-culture bestseller. Judge Hetherington described it as "a book that detailed how to make a pipe bomb".

Images of the evidence haul were sent to the Defence Science and Technology Laboratory (DSTL), an MoD agency that carries out assessments in explosives cases. A scientist wrote: "Some of the contents of the luggage could [DSTL's emphasis] be used for the manufacture of explosives or explosive devices but none of the items (as far as I could tell from the images) were obviously for this purpose and, with the exception of the throwdowns [devil bangers] and model rocket they all appeared to have other non-explosive uses."

Judge Hetherington backed CTC's initial suspicions. Added to the encrypted files, he said, the luggage made it "understandable in those circumstances that the various authorities were highly concerned initially as to whether there was some link to terrorism and a threat to national security".

During sentencing, the judge seemingly confirmed that NTAC staff had been unsuccessful in their attempts to crack the encrypted files - or had not bothered trying. "To this day no one really has any idea as to what is contained in that equipment," he said. One file encrypted using software from the German firm Steganos was cracked, but investigators found only another PGP container.

The suspicion of terrorism was dropped long before trial and JFL was sentenced under RIPA Part III as a general criminal rather than a threat to national security. Although he admitted guilt, JFL argues he did nobody any harm and the offences were all related to not cooperating fully with police.

Despite referencing his solitary existence, Judge Hetherington appeared not to know about JFL's mental health problems and criticised him for not speaking to authorities.

Abandoning normal court procedures, he said: "It was because I was satisfied you would not tell the Probation Service anything significant further that I saw no purpose in obtaining a pre-sentence report which is normally a prerequisite for someone of no previous convictions who has not previously received a prison sentence," he said.

Sticking to normal procedure might have helped explain much of JFL's behaviour in interviews and while on bail. Pre-sentence reports include mental health records and JFL himself sought psychiatric treatment once before, while a computer science student.

His given reason for not cooperating with CTC - the fact that a section 49 notice overrides the right to silence - echoes the original debate over RIPA and encryption. When the law was drafted at the end of the last decade it sparked protests from civil liberties groups and security experts.

In September 2001, shortly after his stint as Home Secretary, when he had introduced RIPA, Jack Straw took to the airwaves to defend the powers.

"It was government trying to put in place increased powers so that we could preserve and sustain our democracy against this new kind of threat," he said in a Radio 4 interview.

"We needed to take powers so that we could de-encrypt commercially encrypted e-mails and other communications. Why? Because we knew that terrorists were going to use this."

News that the first person jailed for the offence of not talking in a police interview has been judged no threat to national security and suffers from a mental condition associated with paranoia and a fear of authorities is unlikely to win RIPA Part III new supporters.

It will also be news to at least the part of government that administers the justice system. On 3 November, Claire Ward, a junior Minister in the Ministry of Justice told Parliament: "Up to the end of 2007 (latest available) there have been no persons reported to the Ministry of Justice as being cautioned, prosecuted or convicted under section 53 of the Act in England and Wales.

"The government are satisfied that offences set in RIPA are appropriate and that the legislation is being used effectively"