Schneier on Security
A blog covering security and security technology.
« Rubber-Hose Cryptanalysis |
| The Skein Hash Function »
October 28, 2008
Keeping Contraband Out of Prisons
Chilling story of a death-row inmate with a contraband cell phone.
If we can't keep contraband out of prisons, how can we possibly hope to keep it out of airports?
Posted on October 28, 2008 at 7:09 AM
• 62 Comments
To receive these entries once a month by e-mail, sign up for the Crypto-Gram Newsletter.
Like someone on Death Row has anything to lose.
Prisons in general though are not hard to breach. Guards are not well paid, and hence the temptation to move in contraband for cash in hand is irresistable. Add the fact it calms things down because the prisoners have their phones and their drugs, and it's about as surprising as teenagers having sex.
@Calum: I didn't realise airport security guards were paid that well either?
So I guess these truly are "Cell" phones... (pause, crickets chirping, pin drops)
Thats the same argument I've used for years for various about things like banning drugs or guns; if you cant keep drugs/guns out of prisons, how can you expect to keep them out of the rest of the country?
I've never been in a prison (well, an operational one, anyway) so I am getting my science from TV here, but I picture them as having a lot of metal; if correct it seems like it would not be hard to make a Faraday cage out of a prison cell and just neutralize (passively, rather than actively jam) cell signals.
Alternatively, they could eavesdrop on the cell signals and maybe learn stuff that they wanted to know? Maybe they are already doing this?
@Calum: Yeah, I was wondering what "charging" a death row inmate was going to accomplish.
I don't even think you can call that "Lax Security." Amazing, especially in a state like Texas. I guess money is always the bottom line, though.
While the linked story about an inmate you tries to blackmail someone via phone is chilling, I find the total seperation inmates suffer even more chilling. Let them have their phones to call their loved ones now and again, the 2.100 $ the inmate in the linked story payed in bribes to get his phone were probably cheaper than a few calls from the prison phone system (those are always extra expensive, to bring the prison more money).
Did you notice the FCC turned down the requests of Texas prison officials to allow a cell phone jammer be installed to block all calls in the facility?
My National Guard unit was called in to quell a prison riot several years ago. We confiscated drugs, knives, and guns from many of the inmates - including those in maximum security.
How did inmates that are stripped searched before entering max security get these items when their only contacts were prison guards? Three guesses.
As long as there is money to be made, some of those in authority will do anything for it.
@roenigk: Yeah a jammer was my first thought but when I read it was turned down I figure its because its effects would be felt outside the prison population to the staff and possibly into the nearby roads and areas. If theres not a lot of cell towers near the prison (arent prisons usually kinda rural?) a jammer could be blocking a large footprint away from the prison itself.
Maybe the FCC feels if there's an escape the people in the are are better served by being able to report it?
Last year a prisoner in Ireland's highest security prison called in to a radio show to reply to a crime reporter who was talking about him.
The ensuing searches turned up several phones, some big screen televisions and a budgie.
As always, the humans are the weak part of the system. Smuggling contraband into a prison without prison officer collusion is one thing, but keeping the contraband for any length of time *requires* their help.
I'm just shooting from the hip here, but it seems an appropriate response would be from the Texas legislature, by drafting laws that would make the penalties for prison guards helping prisoners smuggle contraband into prison be sufficiently harsh that it's no longer 'worth it' for the guards to accept these bribes.
I'd imagine mandatory, lengthy prison sentences would be sobering. (And could be poetically ironic, if the guards end up serving time at prisons where they were formerly staff. I'm sure THAT would be a sobering thought for any guard contemplating the acceptance of a bribe.)
Technically, prisons aren't designed to keep things out, but rather keep people in. If that was the case, rather, the guards, all administrators and visitors would be strip searched each time they entered the facility and not the prisoners.
The problem is: if you can smuggle the things into a death row, then presumably you can smuggle anything anywhere.
In this particular case, though, what is wrong with prisoners having access to mobile phones? Sell them openly in prison and put the money towards something useful.
Here in the UK we are attacked by reform groups because we don't allow prisoners to vote. Perhaps there are some parallels.
Part of the threat is that cellphones could be used to plan/conduct crime, or more importantly, could be used for prisoners to organize themselves to riot against prison staff. I'm no expert, but on the surface, this appears to me to be a very real threat.
who controls controllers etc etc.
on those feeling sorring for the segregation of prisoner: one is their fault, two typically those phones are used to coordinate and carry on their crimes from the prison
In order to keep people in, it *really* helps to be able to keep certain things out, like metal files, lockpicks, etc. so a prison does have to be designed (to some extent) to keep things out.
That said, there don't seem to be many well publicized failures to keep escape tools/equipment out of the prison, so maybe it's working as designed after all...
I feel that contraband will always get into prisons somehow, whether by visitors bringing it in, corrupt staff (and just how much can you vet an employee, and how reliable is that vetting), or the simple technique of throwing it over the wall, a favourite approach in UK prisons. Andy Kershaw described the Manx prison as "full of
heroin", while my own mother's spell as a Red Cross tea lady (honest guv) at another prison brought out many anecdotes of visitors' behaviour. The criminality of these people knows no bounds, law enforcement is just another hazard to them, as like the mobile owner in the feature they have nothing to lose.
Is it surprising that when someone visits their criminal friend or family member in prison that they decide to use a stolen car for the trip? Yes - some visiting days there would be a couple caught like this. Criminal and stupid yes, but how is this behaviour preventable?
There is a tradeoff between thoroughness of scrutiny and morale. If the guards search everyone -- including guards, visitors, dignitaries and their retinues, news crews, executioners, doctors, paramedics, priests, and deliverymen, then they ought to be able to stop nearly all smuggling. This of course will piss of the people being subjected to the indignity of being stopped and searched.
If the guards are trusted because we don't want to hurt their feelings, then we have to accept any crime our choice invites.
What I want to know is where a prison inmate gets $2100 to do anything with? Cash too (since I am pretty sure bribery isn't set up to be done with debit cards and checks)!
When I was young hellraiser, I knew a guy who made a lucrative business getting certain types of contraband into prison. The one that always got me was he would send letters to inmates, with a dose of LSD under the stamp. Apparently it worked very well, although I can't imagine wanting to hallucinate inside a place like that.
They should probably just run radio location systems occasionally.
Another way to go would be to install a cell phone mast themselves. That way they would have control.
Here is the money quote:
>Technology is available that allows cell phone signals to be jammed, but prison officials said they have been unable to get the approval of the Federal Communications Commission to do so.
The reason we're reading this story is because the U.S. Prison system is being frustrated in this area, and hope stories like this one will get them what they want. Otherwise we wouldn't hear about this.
> In this particular case, though, what is wrong with prisoners having access to mobile phones? Sell them openly in prison and put the money towards something useful.
Probably not to Maximum-Security death-row inmates. Getting 3 a.m. phone calls from convicted murderers is pretty intimidating, that's why my phone number has been unlisted for twenty five years...
The real problem here is that for a number of reasons, the United States has the highest per-capita incarceration rate in the world. Between the for-profit privatization of the prison system and the racially-imbalanced rates of incarceration, America is indeed "The Land of the Free..."
I alluded to this in the my post above, but this is a classic case of security economics at work. Not only do prison guards profit directly from helping to get stuff in, it makes their jobs significantly easier, as it turns the relationship between them and prisoners into a business one, and one likely to be conducted with more integrity on both sides.
I agree with hmmm. Treat people humanely - and criminalise the action, not the tool.
It's often (rightfully) said that guns don't kill people, people kill people. The same's true here; cell phones don't make threatening phone calls, people do.
The article is actually pretty full of FUD, anyway. It's all "could be used for this" and "might be used for that", but all in all, it's just one high-profile case that's only getting reported because it's about a senator. If it had been Joe Sixpack the blue-collar worker from the street who'd been targeted, nothing like this would've happened.
If the primary source of contraband is bribed guards, that would explain the lack of escape tools. From a guard's POV, life becomes easier if the inmates have drugs and phones to keep them happy. But most guards will likely see see threats to their own well-being if they smuggle hacksaws.
I heard from a corrections employee that some guards were busted in Oregon for bringing in tobacco inside hallowed-out bars of soap. Doubly-clever.
Once again, Bruce's work strays into territory where I have direct experience. Not as an inmate, at least not yet, but I won't explain further.
What no one wants to admit in all this is the fundamental for-profit nature of the whole thing. The entire prison system was hijacked some twenty-plus years ago by private security firms. It is they who lobbied for harsher sentences for the likes of drug dealing. The same security firms happen to have contractors working in places where raw drug sources are grown, and there is more than ample evidence they supplement their contracts moving the stuff.
The same security firms are major contributors to similar lobbying efforts to make merely passing gas a crime. They fund the efforts behind shaping the philosophy of police training to make them bullies, fund similar efforts to train prosecutors, judges, etc. Anybody living today in the US can easily be put in prison for a lie. Anybody. I've experienced the criminal court system enough to know how that works.
All this noise about how we can fix this singular symptom of cellphones on death row is just hot air until we replace the entire prision industry with something not designed to make a profit.
Interesting commentary. Perhaps a different perspective will shed light.
I was incarcerated (Misdemeanor DUI AKA "Drink Driving" for you UKers) for approximately 6 months and the single most frustrating thing was an inability to reliably communicate with the outside world. While we had access to a "collect call" phone system, it was/is only viable for land lines (thereby completely ruling out the vast majority of young people I know as we only carry mobiles) and is exceedingly expensive. For example, a ten minute phone call to my folks was in the neighborhood of 40 USD.
If I had had an opportunity to sneak a mobile phone and some sort of "crank-style" charger in I would have thought quite seriously about it even though the charges for such a thing would have been more serious than my sentence. (RE-read that and recognize that the math gets quite easier for individuals facing multi-year or longer felony sentences)
To whit, if their is a demand, it will be met. All we have done is monetized the process due to criminalizing it. What's the answer then?
While talk of "Faraday cages" ( not practical as most prisons are made mostly of concrete but thanks for playing) and "active jamming" (as noted above, may create unintended bandwidth disruption outside of the inmate population) are bandied about, you are ignoring the fundamental problem. I.E. if someone wants something more than you wish to keep it from them they will find a way. Prohibition or current USA Drug policy ringing any bells Folks?
A suggestion then. The argument against allowing prisoners to have cell phones seems to be that they will use them to commit/organize crimes and or harass individuals yes? Is anyone familiar with Firefly or it's imitators?
Pre-paid(made purchasable through the Prison "canteen"), PIN controlled-access both for making AND receiving calls (programmed off of a list of approved numbers like spouse, parents, attorney, etc.), cheap. Make incentives for positive behaviors a condition of access to said phones (or perhaps pre-paid minutes) and I think you have a winner. I am not advocating unrestricted access. I recognize that incarceration is intended to be at least somewhat about punitive deprivation (certain victims rights advocates would argue that's all it's about)
Now, will their be some quite clever individuals that will "hack" their new toys to circumvent the limitations? No doubt and those items would be treated as contraband. However, for the vast majority of the inmate population this type of limited but legal access is vastly preferable not to mention economically attractive.
Is it a perfect answer? Well, no. I don't believe that exists. Is it a solution that addresses the fundamental problem and is accommodating to both sides of the issue? I believe so.
@bob: "I was wondering what "charging" a death row inmate was going to accomplish."
Hopefully grant him access to the front of the line?
It's a noble thought, but I don't think it's practical. Just because you control what numbers the phone dials, doesn't mean you can control who answers that call on the other end. Sure, it's my dying grandmothers number, but that's my right hand man answering the phone and taking orders to "remove" key witnesses in my trial.
Just don't see it working with the hardcore criminal set. Like you said, where there is a will, there is a way.
There are many different ways of organizing criminal business of the outside world when in prison, and most of them don't require a mobile phone. While monitoring a legal mobile phone given to an inmate is trivial, it is not so trivial to monitor other ways of exchanging information. Here in Italy inmates who are in prison for a "mafia-related" crime, barely get to talk to the family, every once in a while, through a window and under constant control; anyways, they govern their criminal business and exchange information (both ways) with the outside world.
So, IMHO, letting inmates having a mobile phone is not such a big threat at all.
"The reason we're reading this story is because the U.S. Prison system is being frustrated in this area, and hope stories like this one will get them what they want. Otherwise we wouldn't hear about this."
You have hit the nail on the head.
The prison service wants to minimise costs so it want's to implement mobile phone jammers, and does not want it's pet idiotic solution questioned by those that actuall know something about the subject (which they obviously don't).
And it is quite obvious to any one who cares to think about it the example of a threat phone call was more easily and reliably remided by the traditional process. It's not as though the caller was unknown to the recipient either directly or in context. Importantly jamming the cell phone in the prison would not have stoped a call made by a third person on the condemed's behalf (which is the old fashioned way).
The FCC has quite rightly told the prison authorities to "Foxtrot Oscar", the cellphone service is way to important to allow arbitary organisations with very narrow self interest to disrupt. In the prison authorities case over quite a large area (some US prisons cover hugh tracts of land with public access through them).
The logistics of running an effective jamming service that did not cause disruption for many many times the area of the prison would not be cost effective for the prison to implement. The FCC are only to aware of this and would be the people who would have to deal with complaints not only from the public but other agencies quite a few with fedral or above authority.
Then there are the issues of public safety not just in terms of fire and rescue but also for the police etc.
Then if cell phones can be smuggled in so can two way radios as well.
If the prison authorities get their way how long before an enterprising criminal installed a two way radio system linked to a cellphone outside of the jamming area? (and please don't say it's technicaly to difficult you can buy the equipment to do it for less than 1000USD quite openly on the market google flipjack for one part).
It would be way better for the prison to install cell base stations around their property and do a deal with the phone service providers that enabled all traffic to be recorded (which as we know is quite legal in the US these days ;)
But more simply the FCC know that the prisons do not know what they want or how to ask for it, nor are the prisons prepared to be guided by the FCC which is the typical "we know best" attitude you get from entrenched authority that usually knows no oposition.
I hope the FCC continue in their stance it is the correct one in all respects and the prison authorities real should wise up to the fact.
@ Charles Decker
Well said. This sort of simple subversion is always going to be a problem and has been for ages. Certain individuals in the prison population now utilize 3-way calling to effectively work around call restrictions anyway (I.E. you call a landline, they answer and then make a conference call to a secondary number on your behalf)
I suppose the monitoring that is already done of phone conversations in most corrections institutions would need to be expanded.
However, this is still preferable to a completely unregulated "black" phone that is smuggled in. I think the key component is making it no longer economically attractive to pay king's ransoms to corruptible sources (Guards, support staff, etc.) simply to make phone calls.
"However, this is still preferable to a completely unregulated "black" phone that is smuggled in."
It is becoming clear that it is not only the prison authorities that have no clue as to how the mobile phone system works.
So some sailient facts,
1, The cell network knows to within a few meters of where the cell phone is.
2, The cell it's self knows if you turned the phone on in it's coverage area or you where handed over from another cell.
3, A cell phone only works if the network choses to allow it to place a call.
The second fact alone when combined with the third would stop the use of "contraband cell phones" dead.
What the prison authorities (PA) need to do is as I said aproach the service providers (SP).
A, The SP can automaticly inform the PA when a cell phone is turned on in or immediatly adjacent to their property and to within a few meters. (And in the case of GSM phones they could force the mic on and pipe it to a PA guard or other responsable person).
B, The SP can automaticaly "tap" any call placed from within the PA property or immediatly adjacent to it.
C, The SP can only allow calls to or from phones in the PA property from an approved call list and then only to approved numbers.
And there are a whole host of other things the SP can do based around standard software that is already in use for other purposes.
It's not only not rocket science it's also fairly trivial. All that the PA needs is the co-operation of the SP which it will probably do for a small sum of money (compared to the cost of jamming) or if required to do so via legislation that is already in existance in the US.
Cell phones just make it easier to do what prison inmates already have access to. Certain gangs designate an outside phone number as a "burner" and the owner of that phone line will accept all collect calls from prison and use 3-way calling to patch the inmate to whoever they want to talk to, and act as a switchboard to communicate messages among inmates at different prisons.
Prison guards have confiscated hand-written lists that have been copied over and over, that have the names of hundreds of people (inmates and outsiders) who have been "green lighted" (had a hit put on them) by the gang boss.
The cell phone makes it easier, but it's not like there's much of a barrier for a huge group of men who have nothing to do all day but think of ways to subvert the system.
I remember reading an article a while ago, about how a Guatemalan woman smuggled a grenade into prison, by concealing it in, yes, you guessed it, her Vagina!
02 Mar 2007 02:31:22 GMT
Alert Me | Printable view | Email this article | RSS XML [-] Text [+]
SAN SALVADOR, March 1 (Reuters) - An inmate at an El Salvador jail was caught with a hand grenade stuffed up his backside -- a novel attempt to disguise his apparent escape plans.
Guards at the San Francisco Gotera prison outside the capital San Salvador found the V40 grenade, about the size of a golf ball, lodged up the man's rectum during a security clampdown, a prison spokesman said on Thursday.
They also caught another 16 inmates who each swallowed a mobile phone.
"We'll have to expel the objects and if they won't come out we'll have to perform surgery in hospital," said Alberto Uribe, a spokesman for the El Salvador prison service.
Last year, prison guards found an M67 grenade in the vagina of a female visitor at the overcrowded La Esperanza-Mariona prison on the northern fringes of San Salvador.
Prisoners in the Central American country use weapons to try to escape or attack fellow inmates and prison guards, and use cellular phones to order free gang members to commit crimes or smuggle narcotics.
Woman Allegedly Smuggles Grenade Into Jail
Posted on: Wednesday, 19 April 2006, 21:00 CDT
SAN SALVADOR, El Salvador - A Salvadoran woman was detained after she tried to smuggle into the country's main prison a military grenade and marijuana hidden in her vagina, authorities said Wednesday.
Officials subsequently raised the security level at jails across the country, prison system spokesman Alberto Uribe said, adding the discovery showed "the inmates are planning something."
Lidia Alvarado, 44, was found hiding a cylinder containing the weapon and the drugs, as she entered La Esperanza prison on the northeastern outskirts of the capital of San Salvador, Uribe said.
She was turned over to police and charged with illegal weapons possession and drug trafficking, he said. Police who inspected the M-67 grenade said it was in working condition.
Alvarado was visiting two inmates, serving 25 and 30 years. Each had been convicted of rape, robbery and illegal arms possession.
Prison Director Wilson Galeas was quoted by the daily newspaper La Prensa Grafica as saying it was not the first time Alvarado had visited the two convicts.
Here in Scotland, we're much more civilized. If we want to get drugs into a prison, we slice open a tennis ball, put some crack inside, and lob it over the Saughton Prison Fencing in Edinburgh.
I get calls a couple of times a week from a longtime friend of mine who was sentenced to 20 years in prison. His phone only cost him a $400 bribe to one of the guards.
I spent several years incarcerated. There is a lot of inaccurate information in the posts above. There are so many ways to get things in and while it does happen with guards this is BY FAR the least way things make it in.
The bottom line is when you have nothing better to do and nothing but time on your hands you will find a way to bypass the security mechanisms that are in place.
To Bruces point, this is really the same for airport security. You can add more security to the airport which will be an inconvenience to everyone and really at the end of the day you will have little impact on the person(s) who goal it is to circumvent these measures.
Anybody else read the article and notice that
they arrested Tabler's mother on charges of
introducing contraband into a state prison
apparently solely on the evidence of her
having paid the phone bill.
Granted the charges may have been justified.
I never realized paying a phone bill was a crime.
Or that, if I had my identity (credit-card) stolen,
I could be jailed...
"I never realized paying a phone bill was a crime.
Or that, if I had my identity (credit-card) stolen,
I could be jailed...
You should be more worried that your stolen credit card might be used to purchase child porn online. Naturally, many such purchases are made with stolen credit cards, and naturally the police just arrest whoever's easiest to arrest, leaving you to prove your innocence. Of course, with today's which-hunt mentality towards certain crimes, just the accusation can be life-destroying.
The real story is that prisons are not currently setup to control cell phones, so cell phones make it in. This is known. Suddenly a cell phone is used to threaten a powerful politician, and people take notice.
This is not really about the impossibility of designing controls against contraband, but rather an example of how known vulnerabilities and threats are ignored until a particular asset comes into the picture.
"Cell phones are just about the hottest commodity inside prisons," said the prisons' inspector general, John Moriarty, whose office has opened 743 cases involving cell phones found in Texas prisons.
Brian Olsen, who heads AFSCME, the union that represents some of the prison's 26,000 correctional officers, said the prison should have instituted tougher security policies before threatening calls from a death row inmate to state Sen. John Whitmire, D-Houston, triggered a statewide response.
"They knew they had a serious problem," Olsen said."
So back to Bruce's point of this post...
should the TSA disband the airport security screening as being unworkable?
Besides the savings in direct costs, there would be a savings in time for the flying public and the airlines. Airline traffic would increase. TSA resources could be allocated to areas that have an actual impact on security.
The two issues are slightly dissimilar. If you want to keep contraband out of prison, try keeping more people out of prison, for openers. That and, as pointed out above, quit running prisons for profit.
Keeping people out of the airport, however, is not what it's about. So in that regard keeping the contraband out is another matter entirely.
I would suggest Occam's razor. Two entry points, one for all people traveling (and crew and staffers) and one for deliveries (food/fuel/supplies). Bottlenecks, perhaps, but how else can you secure each flight?
On the other hand...you could take a notion from George Carlin and "Take an effing chance...".
Risk Management is about Risk Acceptance, not 100% Risk Removal.
Actually the question that bugs me is how they charge them (or run the TVs as per an earlier post). Giving these guys access to a hot outlet seems like a bad idea. If nothing else they could try to electrocute a guard or fellow inmate.
at 110 VAC it's not clear they could, but still...
@ DV Henkel-Wallace
Plausible - with some salt water, unless it's a GFI outlet.
Thanks for the review. You make some key points regarding capability. Indeed, the service providers COULD do this relatively easily and at a minimal cost to the prisons. I think you hit the nail on the head about it needing to be written into law though I can foresee their being a TON of resistance to any sort of legislation that dictates network access and it will come from more sources than you might imagine. Your idea is still the most workable thing that I have seen here today. This was an interesting exercise. Thanks!
"...prison guards found an M67 grenade in the vagina of a female visitor..."
Most redundant clarification I have read all week.
Geeze... they kept Osama out of prison well enough.
I'd imagine it'd be a lot easier to smuggle things into a prison than an airport. There's money to be made, and it's mostly harmless. Death row would be particularly hard to secure, as simple human decency and compassion is hard to stamp out.
I think its easier to keep airports safer from contraband than prisons. Prison
officials are directly in touch with inmates for long periods of time and do
tend to develop relationships with them. Also, this kind of stuff in prisons is
a global phenomenon.
Everything you say is technically correct. But, as ever, it is a question of economics, not technology.
Implementing this proposal, to cover all prison areas, at all times, would place a substantial cost burden on all Service Providers. A software feature like this, which would most likely be implemented on the Mobile Switching Center, is likely to cost 1M USD per MSC. There are say 500 Mobile Switching Centers in a network the size of the USA, and 4 services providers networks in a country. That is USD 2B. Then there are the operating costs.
The service providers' shareholders will object if they spend this sort of money without a requirement - which typically means a new licence condition, or a new law. Look at the amount of pushback over the implementation of CALEA from the mid 1990s on, and the bill for that ran into the billions, ultimately paid by the US taxpayer.
Nice catchy phrase.
However, what you can't keep out of prisons isn't the same thing you don't want on airplanes.
It's a balance of motives and opportunity.
For prisons, the motives are usually drugs and comm devices, weapons etc. The opportunity is wide open because the channel (entry points) is wide. That's why it's so hard to prevent smuggling.
With airplanes, the situation is quite different. The TSA approach to identify and throttle channels (suspicious people or potentially dangerous items) to address the threat is realistic. In that case however the motivation for smuggling is quite different.
You're comparing apples to oranges.
I generaly don't care what they take-in as long as they don't come out.
I'm going to try and smuggle Barack Obama and Bin Laden into prison, underneath Joe Biden's hair.
Realise that any techniques used to control the prison population will eventually be used to control the rest of the population.
We are living in a Global Village.
Be seeing you!
A key comment is that radio jamming is not at all effective. Why? Well, all the metal in the prison means that it's quite easy to find a location where most of the jammers are ineffective and the nearest one interferes destructively with its self. Cell phones expect a certain level of interference and make considerable effort to avoid it. The level of jamming needed to reliably cover the whole of a prison; even just the areas where the guards go; will be enough to cause problems in a vast area surrounding the prison.
1, The cell network knows to within a few meters of where the cell phone is.
only a GPS equipped cell phone. Even those typically don't turn on the GPS function without permission and a prisoner could just break that bit of the phone if needed. Network based location is generally much less accurate than that. Also it can quite often be wrong. For example due to reflections. Prisoners would find ways around this whilst outsiders would end up having problems.
2, The cell it's self knows if you turned the phone on in it's coverage area or you where handed over from another cell
To work that requires somewhat special radio planning. There may be ways to persuade your phone to attach to a further away cell first. You cannot block all phones in a city surrounding a prison.
3, A cell phone only works if the network choses to allow it to place a call.
That's generally the job of the network. Anything which stops that is very likely to stop other legitimate customers who happen to be unlucky.
(And in the case of GSM phones they could force the mic on and pipe it to a PA guard or other responsable person).
Only in the case of a phone with a trojan already installed on it. Not that I'm saying that some manufacturers might not put such a trojan by default; To know this can't be common, you should realise it would be extremely easy to detect. If your phone makes a nearby radio buzz continually when you aren't using internet on it then you are being tapped. Also your battery life would quickly go to zero.
B, The SP can automaticaly "tap" any call placed from within the PA property or immediatly adjacent to it.
Because that would be completely legal when you happen to catch "innocent" members of the public walking nearby as well.
You definitely have some reasonable ideas but it's more difficult than that. You need some serious defence in depth.
"Realise that any techniques used to control the prison population will eventually be used to control the rest of the population."
Yeah, and I hate being manacled. They shouldn't be allowed to do that to the whole population.
And I hate being locked in my room at night, that sucks.
And having to get permission to see a visitor.
And not being allowed to touch my visitors, even my wife; I hate that! Why are they allowed to do that to people who have never been convicted of any crime?
And having to wear an orange jumpsuit all the time.
And not being allowed to travel anywhere I like in the country.
> And not being allowed to travel anywhere I
> like in the country.
Heh. You are NOT allowed to travel "anywhere you like". Try going through a military base.
And wait until you get into the "no fly" list.
Travel in US is already more unpleasant and restricted than it used to be in the late USSR.
@ Zygmunt Lozinski,
"it is a question of economics, not technology"
Yes it is and for a number of reasons I won't go into it would probably cost the prisons less than their current communications budjets.
"would place a substantial cost burden on all Service Providers."
Actually no it would not as I will show,
"A software feature like this, which would most likely be implemented on the Mobile Switching Center, is likely to cost 1M USD per MSC."
Actually most ofthe software required has already been written all it requires is bolting together. The MSC is actually not the place to do this. If you think about how "private group calling" that has replaced PMR systems works you will see that it is only a minor extension.
"The service providers' shareholders will object if they spend this sort of money without a requirement"
Actually either the Service Providers or Network Providers could quite easily turn it into a business oportunity with little effort.
"Look at the amount of pushback over the implementation of CALEA from the mid 1990s on, and the bill for that ran into the billions, ultimately paid by the US taxpayer."
I agree there was a lot of pushback over CALEA but it is a done deal the costs are sunk. It is now upto the SPs/NPs to take what they have been given and use it to make money (and a big chunk of the CALEA code will do the better part of this type of activity so the SPs/NPs are effectivly getting a huge subsidy on this).
"A key comment is that radio jamming is not at all effective."
You forgot to mention the costs of the infrestructure and running costs.
Jammers are realy of little use for one other reason. If you assume an illicit radio transmitter like a two radio puts out +30dBm (1watt) in an effective comms channel of +-3KHz and it can work anywhere in a 30Mhz bandwidth this means that your jammer would need to put +42dBM (to override capture effect) into each channel which would need an overall increase of +38dB giving an effective radiated power (ERP) of say +70dBm or +10dBK or 10KW then with an efficiency of only around 20% and the other support systems you could easily be sinking 100KW just for 30Mhz jammed against a walkitalkie... and that is before somebody gets cute with antennas and bumbs that up another 30dB.
" only a GPS equipped cell phone. Even those typically don't turn on the GPS function without permission and a prisoner could just break that bit of the phone if needed. Network based location is generally much less accurate than that."
Back in the early cell days it was found that just using received signal strength was insufficient to decided if a handover should occure. The results of some experiments in the UK (Raynes Park London) showed that with a little bit of software you could fix the old analogue phones to within 100m 70-80% of the time.
"Also it can quite often be wrong. For example due to reflections. Prisoners would find ways around this whilst outsiders would end up having problems."
Yup but using three cell sites around the prison would reduce the probability of this down to less than 1%, but importantly the phone would apear to jump when channel switched which could be used to fix it quite well.
" 2, The cell it's self knows if you turned the phone on in it's coverage area or you where handed over from another cell
To work that requires somewhat special radio planning. There may be ways to persuade your phone to attach to a further away cell first. You cannot block all phones in a city surrounding a prison."
First off it's not just the cell the network has to (find) know where you are to place an incoming call. Therefore your location information is very much known and can be pulled of the SS7 interface with little difficulty (there are companies doing this right now to do things like vehical traffic flow modeling).
And yes with a high gain antenna and some skill you could register at another cell, the point is though a history of your usage and records of where the bill is payed and by whom is going to be a bit of a give away...
"(And in the case of GSM phones they could force the mic on and pipe it to a PA guard or other responsable person).
Only in the case of a phone with a trojan already installed on it."
GSM is a European specification and a large part of it grew out of ISDN under which it is a requirment to be able to switch the mic on under control of the SS7. It would apper that CDMA systems also have built this in as well.
Some switch providers have the function built into their switches by default at a low level, it's just that they only provide the higher level software at a price... (it's soething the Greek Gov got all hot under the collar about not so long ago).
"To know this can't be common, you should realise it would be extremely easy to detect."
You are looking at this the wrong way around. It is not used very often and then (usually) only against very specific targets.
"If your phone makes a nearby radio buzz continually when you aren't using internet on it then you are being tapped. Also your battery life would quickly go to zero."
You need to look up Pico cells, these work by having your phone down to the lowest output level. They are quite common now to cover areas like conferance centers and other places where hundreds or more people might be expected to be together (they are available for about 2K USD).
And modified versions of Pico Cells used by the survalence industry can be picked up for between 5K-10K USD.
" B, The SP can automaticaly "tap" any call placed from within the PA property or immediatly adjacent to it.
Because that would be completely legal when you happen to catch "innocent" members of the public walking nearby as well."
Automaticaly taping and recording phone calls is unfortunatly a fairly common place thing these days. The question is what do you do with the recording...
Well as you would know the numbers of both ends of the call and the network database could easily show the behaviour charecteristics of the near end then filtering down to an inmates illicit phone would be fairly easy.
This due to the fact that workers and visitors to the prison would most likley,
A, have turned on the phone in some other cell either this time or some time in the very recent past.
B, Used the phone in some other cell either this time or in the very recent past.
C, been handed over from non adjacent MSCs in the recent past.
Further the call making and receiving pattern on an illicit phone is likley to be way way different to the norm by some considerable difference.
And as Bruce has posted to this blog in the past there are companies that can actually mine this data effectivly and quickly from data that the law requires to be held.
All in all it should be possible to recognise a legal phone with better than a 99.9% confidence...
"You definitely have some reasonable ideas but it's more difficult than that. You need some serious defence in depth."
Yup and - have other ideas to plug the majority of those holes as well.
The point is it is actually comercialy viable for the SPs/NPs to build such a system as an extra to their existing value added services because if you think about it it's not just the prisons but well neigh every Gov establishment, military base and contracting organisation which deals with information at clasified or above that could use such a system...
Here's a tech solution that would be simpler than active jamming, and legal too.
1. If it's a new prison, put a Faraday cage in the *outside* walls, roof, and floor. (For outdoor areas inside the walls this would involve hanging a net on tall poles.)
2. Have the prison operate its own (cellular) cell inside that cage. This could easily be programmed to:
(a) Deny service to phones not on an approved list;
(b) Allow listening-in or even record all conversations; and/or
(c) If three towers are used, triangulate the location of every phone inside the walls, thus making it easy to find and seize every contraband phone as soon as someone turns it on.
Schneier.com is a personal website. Opinions expressed are not necessarily those of Co3 Systems, Inc.