RF shielding

Thanks for the info, jaclaz. I wouldn't say I've had anywhere near a 50% failure rate with my version of the Black Hole bag. A couple SMS messages on an HTC Thunderbolt are all I've seen. My personal BlackBerry and several iPhone (3GS, 4S and 5) have all been properly shielded by this bag. I'm less than a block from a tower too, so it's a pretty strong signal area.

If possible, get the phones delivered to you in airplane mode. Since I deal with civil cases, this is usually possible.

Sure, but during the cited test the handies in the bags were "bombarded" by a heavy load of data on purpose, SMS, MMS and voice calls, and they compared what was sent to what was received.
If in your real life experience 4 SMS were sent and 2 were received by the Thunderbolt thingy inside the bag, the bag failed for a similar 50%, but if in total two SMS were sent and you received both of them it failed 100%, but if 8 SMS were sent and only two were received you have a much lower rate….

@rjudy55
I am pretty sure you try your best to have your bags shielding effectively ) and I am perfectly confident that the testing you make are as accurate as possible and that your products (newer models) offer added/better shielding capabilities.

One of the points raised by Eric Katz still remains, however.

I perfectly understand how your testing methodology is correct and possibly a much more scientific one (at theoretical level), the approach by Mr. Katz however highlighted how in practical tests - at least for the hardware tested at the time - the sheer data expressed in db (signal attenuation) was not

From the docs on your page (first two items, one with window and one without) the signal attenuation is typically 44-50 db for the "windowed" and 54-60 db for the non-window.

This measures - accurate as they might be - give values that are "meaningless" (please bear with me) from a practical stand point.

As we don't have (and the mentioned thesis only partially answers this) properly terms of comparison, if you prefer we miss some "fuzzy" data.

If you have to describe the distance to (say) a nearby shop, and you are used to Imperial, you would say "Round the corner, no more than 100 yards", another "you" but used to metrical system would probably say "Round the corner, about 100 metres".
Scientifically the two measures are described with an approximation of almost 10 % but the person to which you are giving the information will have anyway a "good enough" kind of info.

What I guess would be useful would be more "real world references", even if less accurate, like "can shield a phone up to (say) 200 meters (or yards) from a tower/antenna".

The procedure of wrapping the (windowed) bag inside another (non-windowed) bag (or other heavily shielded conductor) makes of course a lot of sense, and in theory should also be the recommended procedure, expecially in countries where cellular technology/coverage is exapnding and - even if "yesterday" nothing happened "today" some telephone company has placed a new (or replaced an old one with a much more powerful) apparatus.

This (the measurement of the combined effect of the two bags in terms of signal attenuation) could be in any case a nice added set of data to your documents.

As a subject for research it could be also intersting to evaluate the effectiveness of further layers (such as putting the two bags, one into another into a tin can for added shielding).

As I see it being able to reach 100% (or as nearly as possible to 100%) certainty that during transport and until the "package" is opened in a controlled environment no signals reach the seized device - while being probably overkill in practice (you need to meet two conditions concurrently, being extremely near to a powerful tower AND have something, SMS, MMS, voice sent to the handy in the limited time you are under this "restricted" area of possible influence) might help in having quite a few of the professionals involved sleep better at night.

jaclaz

Thanks for the info, jaclaz. I wouldn't say I've had anywhere near a 50% failure rate with my version of the Black Hole bag. A couple SMS messages on an HTC Thunderbolt are all I've seen. My personal BlackBerry and several iPhone (3GS, 4S and 5) have all been properly shielded by this bag. I'm less than a block from a tower too, so it's a pretty strong signal area.

If possible, get the phones delivered to you in airplane mode. Since I deal with civil cases, this is usually possible.

Sure, but during the cited test the handies in the bags were "bombarded" by a heavy load of data on purpose, SMS, MMS and voice calls, and they compared what was sent to what was received.
If in your real life experience 4 SMS were sent and 2 were received by the Thunderbolt thingy inside the bag, the bag failed for a similar 50%, but if in total two SMS were sent and you received both of them it failed 100%, but if 8 SMS were sent and only two were received you have a much lower rate….

@rjudy55
I am pretty sure you try your best to have your bags shielding effectively ) and I am perfectly confident that the testing you make are as accurate as possible and that your products (newer models) offer added/better shielding capabilities.

One of the points raised by Eric Katz still remains, however.

I perfectly understand how your testing methodology is correct and possibly a much more scientific one (at theoretical level), the approach by Mr. Katz however highlighted how in practical tests - at least for the hardware tested at the time - the sheer data expressed in db (signal attenuation) was not

From the docs on your page (first two items, one with window and one without) the signal attenuation is typically 44-50 db for the "windowed" and 54-60 db for the non-window.

This measures - accurate as they might be - give values that are "meaningless" (please bear with me) from a practical stand point.

As we don't have (and the mentioned thesis only partially answers this) properly terms of comparison, if you prefer we miss some "fuzzy" data.

If you have to describe the distance to (say) a nearby shop, and you are used to Imperial, you would say "Round the corner, no more than 100 yards", another "you" but used to metrical system would probably say "Round the corner, about 100 metres".
Scientifically the two measures are described with an approximation of almost 10 % but the person to which you are giving the information will have anyway a "good enough" kind of info.

What I guess would be useful would be more "real world references", even if less accurate, like "can shield a phone up to (say) 200 meters (or yards) from a tower/antenna".

The procedure of wrapping the (windowed) bag inside another (non-windowed) bag (or other heavily shielded conductor) makes of course a lot of sense, and in theory should also be the recommended procedure, expecially in countries where cellular technology/coverage is exapnding and - even if "yesterday" nothing happened "today" some telephone company has placed a new (or replaced an old one with a much more powerful) apparatus.

This (the measurement of the combined effect of the two bags in terms of signal attenuation) could be in any case a nice added set of data to your documents.

As a subject for research it could be also intersting to evaluate the effectiveness of further layers (such as putting the two bags, one into another into a tin can for added shielding).

As I see it being able to reach 100% (or as nearly as possible to 100%) certainty that during transport and until the "package" is opened in a controlled environment no signals reach the seized device - while being probably overkill in practice (you need to meet two conditions concurrently, being extremely near to a powerful tower AND have something, SMS, MMS, voice sent to the handy in the limited time you are under this "restricted" area of possible influence) might help in having quite a few of the professionals involved sleep better at night.

jaclaz

Within the narrow corridor of probability testing where a device contained in a physical RF dampening field container that may be susceptible, as set out by jaclaz, here are some images at the weblinks below that may assist in providing a visual idea of RF areas and the considered 'dwell time' conditions the container may be exposed to RF conditions when

- static
- slow traverse
- speed

(The research tests may equally consider the robustness/distortion of the container material with respect to being moved around under different conditions during transportation.)

http//trewmte.blogspot.co.uk/2009/08/cell-site-analysis-csa-images-part-2.html

Also the density of masts/towers in an area and the transmission technology/ies that may be relevant

http//trewmte.blogspot.co.uk/2012/04/mini-course-in-cell-site-identification.html.

Lastly, in-building solutions (IBS) have significantly increased and improved, so perhaps a police building or police office in a city building that once previously had poor coverage (externally) may have had an IBS installed (which is another point I believe jaclaz also makes with respect to 'changes').

..

All,

Does anyone know of any RF shielding solutions that provide battery power to keep the acquired mobile device powered?

There maybe situations where if the device looses power, it may not be possible to gain access to the device again due to encryption or difficult passcodes.

The cellphone battery lose energy very quickly when RF shielding,because searching signal never stop.so u can use the Shielding bag with the external battery by USB port)

All,

Does anyone know of any RF shielding solutions that provide battery power to keep the acquired mobile device powered?

There maybe situations where if the device looses power, it may not be possible to gain access to the device again due to encryption or difficult passcodes.

The cellphone battery lose energy very quickly when RF shielding,because searching signal never stop.so u can use the Shielding bag with the external battery by USB port)

There is also the point to make, apart from whether the mobile is going to die on its feet due to loss of battery charge or the battery charge is sustained, whether the RF and network attach state is of equal importance, particularly regarding the OP original point about receiving SMS.

Being able to explaining the RF and network attach state can assist evidentially as to the value and weight to be given to the events as set out by the OP.

At some stage confirmation as to what is happening and can be seen on the screen with the handset that is switched on and contained within a RF dampening field container/chamber may assist a particular issue.

How often do you see a report containing a statement, and maybe with a photo, that in the dampening field

- the mobile had 'no coverage' as depicted by the symbols on the screen
- the mobile phone went into emergency calls only mode
- the screen was blank other than mobile screen mode

When considering these issues the standards do provide useful observations about the RF and network attach state. I have used one example from a GSM/ETSI TS for 1999 to illustrate that nothing I am saying is new, it has always been there Using the standards to help define the technical level of the issue raised by the OP may assist.

For instance absolutely no RF signal and no attach state may possible produce a statement relevant to 'nothing got through'. In the emergency calls state an attach state may occur but the likelihood that the emergency calls channel would be used to send commercial or private SMS text messages would appear unlikely. However, the OP identified receipt of an SMS, but it is not clear whether this came form the subscriber home network or delivered by a roaming network or third party proxy manager. It does confirm however that technically the subscriber was attached to a network, but what we do not know at this stage is whether the mobile was able to send an acknowledgement that the text message was received or whether the network would continue to transmit the SMS at interval for the suration of the 'delivery period' requirements.

Studying and understsanding the locale in which the container was present at the time of the unwanted SMS intrusion and noticing the density of masts/tower and the transmission technology/ies around it (the container) may assist investigate how the SMS message made it through the dampening field, can be included as part of the investigation and reported as necessary.

if money isn't a problem have a look at the new mobile faraday cage of the forensic institute in The Netherlands.
http//www.forensicinstitute.nl/products_and_services/forensic_products/faraday_cage/

Here's a nice breakdown with some indicators of signal to db. http//powerfulsignal.com/cell-signal-strength.aspx.

Yes and no.
Meaning yes ) , it is a nice generic explanation , but no ( , it is too generic to be of any practical use .

I know how it is easy to fall in the two extremes of "too generic/simple/simplified and thus unuseful" or "too technical/difficult and thus unuseful as well", what I find is needed is often the actual "meanigful" data (that only the technical/difficult version contains) but simplified into "layman's term" as much as possible.

If you want a quick laugh, check this
http//www.msfn.org/board/topic/141874-gs-and-gs-and-internet-noise/
where I hopefully solved the issue about "How much is 300 g?"

jaclaz

if money isn't a problem have a look at the new mobile faraday cage of the forensic institute in The Netherlands.
http//www.forensicinstitute.nl/products_and_services/forensic_products/faraday_cage/

Nice looking piece of kit. This may seem like an injustice to NFI's marketing blurb, and apologies in advance for any hurt feelings, but the kit doesn't look easily portable.

I read the leader information on the webpage link you gave and it states (below), generally speaking, nothing gets in with respect to EM signals. And (shouldn't really start a sentence with an 'And') NFI has a high reputation and it is expected that NFI will work to high standards anyway. I just wondered though, do you know whether NFI conducted an analysis of what is happening with the device and its internal activity onced locked inside and switched ON inside the Faraday container and what their analysis found?

No electromagnetic signals

A Faraday cage is a container made of a conducting material that filters out electromagnetic signals. A mobile phone placed inside the cage therefore cannot receive calls or be wiped remotely. Investigators using the cage's special conductive gloves can put their hands in the cage, to retrieve and secure the most important data immediately. They can see what they are doing on a monitor./

The other statement I noted was

Improvements

The NFI has examined the weaknesses of existing Faraday cages and developed a new model in collaboration with police forensic investigators.

So when they say 'weaknesses of existing Faraday cages' is that confirmation they mean Faraday containers on the market, generally, and, if so, do they have the research we can read please as to which ones they have found to be shown to have weaknesses?

what I find is needed is often the actual "meanigful" data (that only the technical/difficult version contains) but simplified into "layman's term" as much as possible.

So we need to present together technical meaningful information and non-technical meaningful information so that when shown the layperson can follow it

If you want to see the full image above (for windows users) right click the mouse and select 'view image'. For MAC users just push any key and something happens without an OOM, errr…wont it!?!

ps - Jamie is there a way we can show images at site that are not half obliterated by the additional forum bar at the side without having to resize an image to load at FF (as this can distort features in the image) please?

So we need to present together technical meaningful information and non-technical meaningful information so that when shown the layperson can follow it

I am clearly failing to see your point. ?

Unless I am mistaken a not-so-little part of the members had the false impression that these carrying bags were something akin to a write blocker, something "binary", on/off or black/white.

What came from the mentioned sources is that they are instead a sort of "muffler" for signals/radio frequencies.

This means that the final user might be convinced that he/she is using a "totally safe" protection whilst in reality there may be cases when signals "go through" and can somehow modify the evidence handy.

It would be logical to provide "real life examples" of when this may happen, knowing that not everyone - though being an excellent digital forensic examiner or LE officer - might have a specific knowledge on cellular networks, signals, etc. (particularly since - from what I get from the board posts - there is a tendency to have evidence collection and delivery to the laboratory a separate step, often performed by other people, from the actual analysis of the device).
I.e. it seems to me like the mere "collection and delivery" is often carried out by people that might have only the specific training/knowledge for these steps, and possibly lack the higher degree of instruction on cellular networks that the actual forensic expert might have.

Of course it is very possible that I am the only one that has difficulties in "digesting" db attenuation of signals and actual minimum "safe" levels and all the rest oops , in which case I will gladly "downgrade" the question about these thingies from a "useful to the community" question to a "jaclaz's personal" question.

jaclaz