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Author Topic: Smoked glass security threat?
Ashitaka

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Icon 1 posted April 20, 2009 04:21      Profile for Ashitaka     Send New Private Message       Edit/Delete Post   Reply With Quote 
Many companies, including a bank near where I live, use smoked glass to block passers by from seeing the computer screens and keyboard of their computers. I had the idea that this with modern technology would be a very easy safety system to bypass and gain access to the computer system. This is just a theoretical mind exercise as I donít have the programming skills to do such a project.

I think the smoked glass is insecure because it is like a mono-alphabetic substitution cipher. The photon travelling from the computer screen always takes the same path to become obscured. (or the photon bouncing off the keyboard and travelling through the smoked glass.) If one were to set up a camera on the other side of the smoked glass, a simple brute force decryption method should be able to crack such a simple code. Instead of the code being a letter that has been obscured, it is a pixel from a defined resolution you would need to read the screen. So there are a few million pixels to be deciphered, but you have all the time you need. Decipher them one by one, and then save them. They would have to replace the smoked glass to change the encryption cipher. This would work at the bank near where I live because the smoked glass is an exterior window.

Theoretically, does anyone think this would or would not work?

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"If they're not gonna make a distinction between Muslims and violent extremists, then why should I take the time to distinguish between decent, fearful white people and racists?"

-Assif Mandvi

Posts: 3089 | From: Switzerland | Registered: Feb 2006  |  IP: Logged
Stibbons
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Icon 1 posted April 20, 2009 12:03      Profile for Stibbons   Author's Homepage     Send New Private Message       Edit/Delete Post   Reply With Quote 
quote:
Originally posted by Ashitaka:
The photon travelling from the computer screen always takes the same path to become obscured. (or the photon bouncing off the keyboard and travelling through the smoked glass.)

I think this is a flawed assumption. On an atomic/sub-atomic level this doesn't hold up, as a photon can take any number of routes from A to B doing all kinds of crazy quantum jazz on route. This is of course if I remember my 2nd year physics courses in anywhere near enough detail! [Razz]
Posts: 1141 | From: UK | Registered: Dec 2003  |  IP: Logged
Ashitaka

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Icon 1 posted April 20, 2009 12:50      Profile for Ashitaka     Send New Private Message       Edit/Delete Post   Reply With Quote 
quote:
Originally posted by Stibbons:
quote:
Originally posted by Ashitaka:
The photon travelling from the computer screen always takes the same path to become obscured. (or the photon bouncing off the keyboard and travelling through the smoked glass.)

I think this is a flawed assumption. On an atomic/sub-atomic level this doesn't hold up, as a photon can take any number of routes from A to B doing all kinds of crazy quantum jazz on route. This is of course if I remember my 2nd year physics courses in anywhere near enough detail! [Razz]
Quantum jazz doesn't come into play here, I think. The light would travel in a straight line, if not for the particle in the glass which bounces it, every time, in a new (same) direction. I think of the gass like a mirror, but because the particles in the glass are not uniform the light gets bounced into a jumble immage instead of a clear image. A computer should be able to correct this.

--------------------
"If they're not gonna make a distinction between Muslims and violent extremists, then why should I take the time to distinguish between decent, fearful white people and racists?"

-Assif Mandvi

Posts: 3089 | From: Switzerland | Registered: Feb 2006  |  IP: Logged
maximile

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Icon 1 posted April 20, 2009 13:15      Profile for maximile   Author's Homepage     Send New Private Message       Edit/Delete Post   Reply With Quote 
Can you explain how you'd be able to decipher it? Each pixel emits nearly a hemisphere of light, rather than just a single ray, so every sample point outside the glass would be affected by every pixel on screen, by a greater or lesser amount. Seems like a difficult task.

I was reading about insecurity in blurring or pixellating passwords and so on in screenshots, and it was demonstrated that they could often be decoded by setting up the screen in the same way and blurring the same area by the same amount for every possible password. Then compare with the original censored screenshot and try the one with the least difference. So maybe you could do something like that in this situation, but you'd need access to the computer and a camera with very high accuracy. Realistically, changes in ambient lighting and so on would make it impossible.

Posts: 1085 | From: London, UK (Powys, UK in hols) | Registered: Feb 2005  |  IP: Logged
TheMoMan
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Icon 1 posted April 20, 2009 14:50      Profile for TheMoMan         Edit/Delete Post   Reply With Quote 
_______________ Sheesh __ I was accused of being Paranoid because I want WinBlows, to be on a Live CD so hackers can't mess with the OS, now you are worried about frosted/smoked glass blurring. Next will it be Polarized film and the straight on only image?

Don't you think that by the time you set up the gear to capture the images, that the bank would be on to you. I would worry about the possibility of reading the ethernet traffic with a radio scanner.

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Those who would give up essential liberty to purchase a little temporary safety deserve neither liberty nor safety.


Benjamin Franklin,

Posts: 5835 | From: Just South of the Huron National Forest, in the water shed of the Rifle River | Registered: Sep 2002  |  IP: Logged
The Famous Druid

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Icon 1 posted April 20, 2009 15:10      Profile for The Famous Druid     Send New Private Message       Edit/Delete Post   Reply With Quote 
I suspect that the situation would be too 'chaotic' for your attack plan to work in real life.

Even if the decoding could be done, it would probably only work if the camera and window were held _exactly_ in place. If the window moved even a little, (eg, vibrating from nearby sound, or expanding/contracting with changes in temperature) your translation matrix could be screwed.

Also, remember that the image you see is affected by light from both sides of the glass, you'd have to carefully control your side as well, theoretically passers-by many metres from the glass could cause interference.

btw - While we're being paranoid, there was an article on /. a while back about hackers who can eavesdrop on the electrical impulses from the keyboard cable from 20 metres away.

It's probably best to do all your secret stuff in a tinfoil privacy tent.

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If you watch 'The History Of NASA' backwards, it's about a space agency that has no manned spaceflight capability, then does low-orbit flights, then lands on the Moon.

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Ashitaka

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Icon 1 posted April 21, 2009 01:33      Profile for Ashitaka     Send New Private Message       Edit/Delete Post   Reply With Quote 
Probably wouldn't work, I just had the idea because I went for a walk one night and I could see through smoked glass that someone had left a computer running. I could identify the screen saver as it was the four colored Windows(R) logo that jumps around the screen ( Default XP(R) screensaver) I just thought with a bit more resolution I could read a secret bank file over a shoulder during the day.

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"If they're not gonna make a distinction between Muslims and violent extremists, then why should I take the time to distinguish between decent, fearful white people and racists?"

-Assif Mandvi

Posts: 3089 | From: Switzerland | Registered: Feb 2006  |  IP: Logged
fs

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Icon 1 posted April 21, 2009 03:05      Profile for fs   Author's Homepage     Send New Private Message       Edit/Delete Post   Reply With Quote 
quote:
Originally posted by The Famous Druid:

btw - While we're being paranoid, there was an article on /. a while back about hackers who can eavesdrop on the electrical impulses from the keyboard cable from 20 metres away.

They probably read Cryptonomicon. And so should you guys, if you haven't.

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I'm in ur database, makin' moar recordz.

Posts: 1973 | From: The Cat Ship | Registered: Mar 2002  |  IP: Logged
TheMoMan
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Icon 1 posted April 21, 2009 03:50      Profile for TheMoMan         Edit/Delete Post   Reply With Quote 
___________________ QRP __ The radio sport of seeing how far or at what distance you can read a message on low power. A ham contact friend of mine routinely contacts we from Eastern Penn. to North Mid Mich. a distance of 517 Miles he uses less than five watts or input power, so the out put is around three watts of signal. I must admit that the receiver I use has very good ears, and I often hear stations that I cannot hit with one hundred watts output. My best link with my gear was into Santiago Chile, or over the pond into Austria.

Now the biggest problem I have is keeping my own Computers out of the receive pass band of my gear. I shut down the router, and this old cowbox running Knoppix when I head out to the barn, and the comp. out there is grounded and almost in a faraday cage. I still get processor noise but it is in an area of the pass band that I usually don't use.

My antennas are all some distance from the barn, fifty to one hundred meters, so that I do not get cooked by RF.

So ASH if your bank used a Blue tooth keyboard or gasp a wireless one NO ONE'S DATA would be safe.

--------------------
Those who would give up essential liberty to purchase a little temporary safety deserve neither liberty nor safety.


Benjamin Franklin,

Posts: 5835 | From: Just South of the Huron National Forest, in the water shed of the Rifle River | Registered: Sep 2002  |  IP: Logged
Ashitaka

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Icon 1 posted April 21, 2009 04:10      Profile for Ashitaka     Send New Private Message       Edit/Delete Post   Reply With Quote 
quote:
Originally posted by fs:
quote:
Originally posted by The Famous Druid:

btw - While we're being paranoid, there was an article on /. a while back about hackers who can eavesdrop on the electrical impulses from the keyboard cable from 20 metres away.

They probably read Cryptonomicon. And so should you guys, if you haven't.
OK what doe the back cover say?? (what is the book about)

On a side note, the web site linked, while it has OK eye candy (it's dark and sh!t) sucks 'cause in five minutes I couldn't figure out what the book was about and surfed away. And five minutes on the Internets is like for-ever attention -span-wise...

Oooo increase my bust size

/me clicks

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"If they're not gonna make a distinction between Muslims and violent extremists, then why should I take the time to distinguish between decent, fearful white people and racists?"

-Assif Mandvi

Posts: 3089 | From: Switzerland | Registered: Feb 2006  |  IP: Logged
TheMoMan
BlabberMouth, a Blabber Odyssey
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Icon 1 posted April 21, 2009 06:54      Profile for TheMoMan         Edit/Delete Post   Reply With Quote 
_______________ ASHitaka __ These two products and a van with darkened windows, and a little Wardriving and you can find all sorts of data for the taking.


http://www.radiolabs.com/products/antennas/2.4gig/14eleyagi.php

http://www.sigma6mobile.com/o2hipowicads.html

Actually I wonder how secure my Credit Union is?

--------------------
Those who would give up essential liberty to purchase a little temporary safety deserve neither liberty nor safety.


Benjamin Franklin,

Posts: 5835 | From: Just South of the Huron National Forest, in the water shed of the Rifle River | Registered: Sep 2002  |  IP: Logged


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