Faraday Bags don't work.. what do you do?

On your question - we have test point specs for cell and WiFi frequencies, as well as real world testing in various environments. But these days we've just reduced it to a single spec like, "Average 70dB attenuation" because our customers don't equate a spec to "this bag will work" or "this bag won't work" anyway. They always want to get a sample and test it for themselves. It's easier to get a general idea of shielding from an average specification. A 45dB spec is very different than a 70dB average spec, and that's pretty easy to understand.

rjudy55 you stated you have test point specs for Cellular and WiFi frequencies. Do you have test results for and can you confirm, please

1) Complete frequencies detected and measured attenuation inside the container area before the bag is opened but with no seized target device inside?

2) How long does it take to open the bag?

3) Complete frequencies range detected and measured attenuation inside the container area when the bag is opened but with no seized target device inside?

4) How long does it take to close the bag?

5) With a seized target device inside the closed bag how long does it take for cut-off from all external frequencies and the measured attenuation?

The questions above are not to discredit the product you referred to but unanswered questions likes these could allow profound negative impact on seized target devices regarding previously stored artefacts that were there on mobile etc. devices prior to seizure.

At the moment, there is no standard that these bags are tested too. Because of this, I am working with a professor who is the chair of the IEEE EMC Society Standards Education and Training Committee. He is currently working on a standard - so there is at least a baseline.

Ref current testing, our range of faraday bags, (Phone Shield, Tablet Shield, Laptop Shield, Holdall Shield, ID Shield and Card Shield), are all tested by him in his labs.

If you would like to see the results, (unfortunately, I cannot post them on this forum and they are not online yet), please feel free to contact me directly and I will gladly forward them to you.

Regards,

Simon
www.faradaybag.com

At the moment, there is no standard that these bags are tested too. Because of this, I am working with a professor who is the chair of the IEEE EMC Society Standards Education and Training Committee. He is currently working on a standard - so there is at least a baseline.

Ref current testing, our range of faraday bags, (Phone Shield, Tablet Shield, Laptop Shield, Holdall Shield, ID Shield and Card Shield), are all tested by him in his labs.

If you would like to see the results, (unfortunately, I cannot post them on this forum and they are not online yet), please feel free to contact me directly and I will gladly forward them to you.

Regards,

Simon
www.faradaybag.com

Well, I may as always be wrong, but test methodology and results that are not public and that are not publishable are IMHO even worse than no tests at all.

And in the
http//www.disklabs.com/faraday-bags/

Effective shielding at 900Mhz, 1.8Ghz, 1.9Ghz, 2.1Ghz, (2G, 3G, 4G), 2.4Ghz, (Bluetooth 1, 2, 3, 4 and WiFi) up to 70dB. 1.22Ghz & 1.57Ghz (SatNav/GPS).

The "effective … up to 70 db" sounds a lot like the "average" seen before, unless the way the tests are carried is described (besides whether a standard exists or not) and the actual results of the tests are available, it is a mostly meaningless quantity.

Nice to know, though unless my (admittedly very limited and remote) memory of decibels being a "logarithmic" unit of measure fails me, seemingly your bags "up to 70 db" are much less 😯 attenuating than the ones by rjudy55 with their "80db average attenuation", as a 10 db differences indicates that there is a 10x factor, which is improbable, given that both should be using more or less the same kind of technology/materials.

-70 db should be 1/10,000,000
-80 db should be 1/100,000,000

more generally (roughly) every -3db power is halved.

jaclaz

Jaclaz,

Send me your email address and I will give you the full report, commissioned by Disklabs.

Ref the claims of other bags, I have had some of them tested too. Their published 'results', have little to do with actual results ;0)

Simon

(You wont be added to any email list, I promise!)

Jaclaz,

Send me your email address and I will give you the full report, commissioned by Disklabs.

Thank you very much for your kind offer, but as said it won't be of use, there is no hurry whatever, when you will be able to publish those tests/reports I will be happy to read them, and comment them.

The old, public and published experiment by Dr. Alistair Duffy at DeMontfort University
https://web.archive.org/web/20120730142350/http//www.faradaybag.com/faraday-bag-testing/demontfort-university-faraday-bag-testing.html
came out with around 30 db attenuation in the 1800-2100 Mhz range, so your new specs of up to 70 db over a much wider range sounds like a very good achievement, in power ratio from around 1/1,000 to 1/10,000,000, or a 10,000x improvement.

Ref the claims of other bags, I have had some of them tested too. Their published 'results', have little to do with actual results ;0)

I guess that depends - besides the actual honesty or accuracy of the vendors (and of their marketing department wink ) also on the actual testing methodology.

(You wont be added to any email list, I promise!)

Did you assume that I would provide you not with a "disposable" e-mail address? 😯
D

jaclaz

JacLaz,

Your Points
1. Claims and results - I wholly agree. Those with knowledge of the subject matter will also understand that. This is why Prof Duffy, (he's been promoted), is trying to write a standard - so that the claims will actually mean something, (surely its not the high point thats relevant, its the lowest readings?)

2. Honesty and accuracy of vendors - Sadly, some are more honest than others. I saw the original results - they are different to the published ones.

3. I did think you would put a 'disposable' email address out there, yes!

My test results are a Word document with images and graphs incorporated in it. I cant upload the word doc on here - hence offering to email you directly.

Simon

Its taken a bit of time, but this might work?

Nice ) , it works OK, though if you have access to
http//www.disklabs.com/wp-content/uploads/2016/06/
why don't you upload a .pdf and post a link to it?

It seems like there is a good correlation between the newly devised testing setup and results in a more conventional MSRC.

Sorry for the Dr. vs. Prof. oops , the faculty page must be outdated
http//www.dmu.ac.uk/about-dmu/academic-staff/technology/alistair-duffy/alistair-duffy.aspx

The procedure is counterintuitive (to me) but surely the math and physics behind it are valid.

I mean, to me (in my declared ignorance of these matters) is like testing the noise reduction of a headset by (instead of putting them on a dummy head with microphones in place of the ears and recording how much attenuation there is with and without the headset) using the ear cup to muffle the source of the noise.

If I read that paper correctly, what is measured is the capability of the bag to prevent radio signals to exit from the emitter inside the bag, whilst the "real world use" is to have radio signals be prevented from entering the bag.

Anyway the next step would be to correlate results of the (new or old) test methods expressed in dB and actual effectiveness in the field, i.e. with experiments similar to the one mentioned on the "other" thread by Purdue University
http//docs.lib.purdue.edu/cgi/viewcontent.cgi?article=1033&context=techmasters&sei-redir=1

Thank you for sharing this new interesting piece of info.

jaclaz

JacLaz,

No problems!

I just hope that you can see that we are doing what we can to further this field, rather than just putting up some spurious claims.

If you want a sample to play around with, let me know.

Regards,

Simon

Thank you for posting your report Simon (xx0033).

There are standards and guidelines for shielding devices that will have relevance not only to evidence collection at site but also for handling evidence in the lab

Shielding effectiveness in the frequency range of 30 MHz to 2000 MHz according to VG95373 Part 15

For EMC shield IEC 61587-3 requirement 3 spec covers range of 30 MHz to 1 000 MHz

IEC 61000-4-31995, Electromagnetic compatibility (EMC) – Part 4 Testing and measurement techniques – Section 3 Radiated, radio-frequency, electromagnetic field immunity test

CISPR 16-11993, Specification for radio disturbance and immunity measuring apparatus and methods – Part 1 Radio disturbance and immunity measuring apparatus

FARADAY P - dB Effective Shielding (EMI duct tests) according to EN 60512-23-3 (1 conductive layer)

Testing IEEE 2992006 shielding panels (1GHz to 6GHz)

Evaluation of Shielding Materials (MIL285, IEEE 299, ASTM D4935)
ASTM D4935 30MHz - 1.5GHz

There is an interesting reference to an anecdotal report mentioned during oral evidence given in the US Court case Riley v California No.13-132 Tuesday, April 29, 2014

http//www.supremecourt.gov/oral_arguments/argument_transcripts/13-132_h315.pdf

13 MR. DREEBEN I have anecdotal reports from
14 the F.B.I. that that has happened, that they have looked
15 into the question of to what extent can you protect a
16 phone through the use of things like Faraday bags. I
17 think one of the important things to notice, if you
18 throw a phone into a Faraday bag, which is supposedly
19 going to be able to block network signals, when you open
20 it up, it has to be similarly shielded or it will pick
21 up a signal from a cell tower, and that will wipe the
22 phone. And the F.B.I. tried to build a Faraday room in
23 a building that they later discovered Verizon had put up
24 a cell tower on it, and that cell tower put out a strong
25 enough signal to go right through the Faraday room.

It provides an indication at least to the potential lengths evidence collectors and examiners might consider how to implement the whole process and procedures (best practice) from start to end without a break in the chain of causation.

The question asked to rjudy55 recently (repeated below) was intended to discuss metrology to identify where "uncertainty" existed from the point of collection of a device, then placed into a shielding container and sealed etc.

On your question - we have test point specs for cell and WiFi frequencies, as well as real world testing in various environments. But these days we've just reduced it to a single spec like, "Average 70dB attenuation" because our customers don't equate a spec to "this bag will work" or "this bag won't work" anyway. They always want to get a sample and test it for themselves. It's easier to get a general idea of shielding from an average specification. A 45dB spec is very different than a 70dB average spec, and that's pretty easy to understand.

rjudy55 you stated you have test point specs for Cellular and WiFi frequencies. Do you have test results for and can you confirm, please

1) Complete frequencies detected and measured attenuation inside the container area before the bag is opened but with no seized target device inside?

2) How long does it take to open the bag?

3) Complete frequencies range detected and measured attenuation inside the container area when the bag is opened but with no seized target device inside?

4) How long does it take to close the bag?

5) With a seized target device inside the closed bag how long does it take for cut-off from all external frequencies and the measured attenuation?

The questions above are not to discredit the product you referred to but unanswered questions likes these could allow profound negative impact on seized target devices regarding previously stored artefacts that were there on mobile etc. devices prior to seizure.

Of course rjudy55 isn't responsible for obtaining test results, but it does help if we can learn something beyond here is a faraday container and the manufacturer identifies minimal details about the containers characteristics. xx0033 report goes some way towards that goal and sets out the proposed approach for testing materials for a faraday container to determine its characteristics that provides for part of the process involved with seized evidence.

What the xx0033 report is not intended to do deal with though is the scene of crime or evidence collection point relevant to human intervention (the seizing party). The above human intervention equally needs attention along with the length of time it takes to create radio isolation once inside the container (risk). In 2015 EDEC Digital Forensics published in the January

White Paper- WiFi Testing in Silence
Flexible EM Shielding Solution for Isolating WAP’s of Interest
https://d12yy4d2hk49m1.cloudfront.net/wordpress/wp-content/uploads/2015/01/WifiIsolationWhitepaper_as_published-1.pdf

The White Paper in my view identifies very realistic issues (but to a lesser extent than the questions above) about (a) opening and closing faraday containers (b) what is happening inside the container once sealed © how long does it take for any radio signals inside the isolated area to diminish and so on. EDEC test result feedback

Nearly all access points are cut off within the first 20 seconds of the test. Remaining signals continue to decrease in strength over time until only the target signal (blue) and the close proximity noise generating AP (red) were detectable. As soon as the bag is reopened, the wifi sensor re-acquires nearly all of outside networks.

There is something quite significant in those practical test findings because they raise the notion (i) has the container been sealed completely or are the materials limited in compliance? (ii) what changes are occurring to the seized device inside the container just after insertion into the container? (iii) for how long is there a risk of exposure to change? (vi) could leakage occur enabling simplex or duplex signalling whilst moving away from the point at which evidence is seized? and so on….

There is lots more on this subject and I can produced more if there is the interest.