Telephone Scramblers

P

Paul Burridge

Guest
There's plenty of software out there to protect the privacy of our
e-mail communications, but I don't recall ever seeing any commercially
produced phone scramblers. This seems a bit odd on the face of it.
Maybe a gap in the market! If one were to set about designing such a
device (and its unscrambling counterpart for the remote phone) how
would one go about it? How might such a device be implemented? Just
curious to get a mental outline/block diagram for such a system....

Thanks,

p
--

"What is now proved was once only imagin'd." - William Blake, 1793.
 
Spehro Pefhany wrote:
On Mon, 08 Nov 2004 13:32:17 +0000, the renowned Paul Burridge
pb@notthisbit.osiris1.co.uk> wrote:


There's plenty of software out there to protect the privacy of our
e-mail communications, but I don't recall ever seeing any commercially
produced phone scramblers. This seems a bit odd on the face of it.
Maybe a gap in the market! If one were to set about designing such a
device (and its unscrambling counterpart for the remote phone) how
would one go about it? How might such a device be implemented? Just
curious to get a mental outline/block diagram for such a system....

Thanks,

p


What capabilities does the foe have?


Best regards,
Spehro Pefhany
Not enough to break the DES...sounds like a simple A/D->processor->modem
to me.
 
On Mon, 08 Nov 2004 13:32:17 +0000, Paul Burridge
<pb@notthisbit.osiris1.co.uk> wrote:

There's plenty of software out there to protect the privacy of our
e-mail communications, but I don't recall ever seeing any commercially
produced phone scramblers. This seems a bit odd on the face of it.
Maybe a gap in the market! If one were to set about designing such a
device (and its unscrambling counterpart for the remote phone) how
would one go about it? How might such a device be implemented? Just
curious to get a mental outline/block diagram for such a system....

Thanks,

p
We can all be scrambled these days. I use VoIP for well over 90% of my
telephone calls now.

d
Pearce Consulting
http://www.pearce.uk.com
 
Paul Burridge <pb@notthisbit.osiris1.co.uk> wrote:
There's plenty of software out there to protect the privacy of our
e-mail communications, but I don't recall ever seeing any commercially
produced phone scramblers. This seems a bit odd on the face of it.
Maybe a gap in the market! If one were to set about designing such a
device (and its unscrambling counterpart for the remote phone) how
would one go about it? How might such a device be implemented? Just
curious to get a mental outline/block diagram for such a system....
1G compact-flash cards are now very cheap, not to mention DVDs.
At 8kbits/second, this is ten days talking using a one-time pad.

This does require a secure means of delivering the key, but it's the
only way to absolutely guarantee uncracability.
There is always rubber-hose cryptography though.
 
On Mon, 08 Nov 2004 13:32:17 +0000, in sci.electronics.design you
wrote:

There's plenty of software out there to protect the privacy of our
e-mail communications, but I don't recall ever seeing any commercially
produced phone scramblers. This seems a bit odd on the face of it.
Maybe a gap in the market! If one were to set about designing such a
device (and its unscrambling counterpart for the remote phone) how
would one go about it? How might such a device be implemented? Just
curious to get a mental outline/block diagram for such a system....

Thanks,

p
There was a Signetics hardback apps books, aeons ago, when early PLL
ics came out (ne560?) that had an audio frequency inverter for doing
exactly this. Sorry, dont know where my copy is.



martin

Serious error.
All shortcuts have disappeared.
Screen. Mind. Both are blank.
 
martin griffith wrote:
On Mon, 08 Nov 2004 13:32:17 +0000, in sci.electronics.design you
wrote:

There's plenty of software out there to protect the privacy of our
e-mail communications, but I don't recall ever seeing any commercially
produced phone scramblers. This seems a bit odd on the face of it.
Maybe a gap in the market! If one were to set about designing such a
device (and its unscrambling counterpart for the remote phone) how
would one go about it? How might such a device be implemented? Just
curious to get a mental outline/block diagram for such a system....

Thanks,

p
There was a Signetics hardback apps books, aeons ago, when early PLL
ics came out (ne560?) that had an audio frequency inverter for doing
exactly this. Sorry, dont know where my copy is.
This kind of encryption is too easy to crack.

VoIP will make various digital encryption techniques easy to implement.
Keep in mind that most VoIP systems are designed to interface with a
POTS system and as such must do one half of the conversion at central
office sites which can be compromised. Only a call between two VoIP
systems can reliably encrypt. But once this requirement is met, an
encrypted call is really nothing more than VoIP over a VPN or through an
ssh tunnel, both protocols being readily available.

--
Paul Hovnanian mailto:paul@Hovnanian.com
------------------------------------------------------------------
What color is a chameleon looking in a mirror?
 
On Mon, 08 Nov 2004 13:32:17 +0000, Paul Burridge wrote:

There's plenty of software out there to protect the privacy of our
e-mail communications, but I don't recall ever seeing any commercially
produced phone scramblers. This seems a bit odd on the face of it.
Maybe a gap in the market! If one were to set about designing such a
device (and its unscrambling counterpart for the remote phone) how
would one go about it? How might such a device be implemented? Just
curious to get a mental outline/block diagram for such a system....
A millennium or so ago, I saw a project in Popular Somethingorother,
where they just used a ring modulater on either end, and an agreed-on
carrier.

One of the suggestions was that for modulation, you and your
co-conspirator just tune to the same local radio station. ;-)

Cheers!
Rich
 
Paul Burridge wrote:
any commercially produced phone scramblers.
Not commercially produced, but there was the "harmless little box",
made before the liberalization of ITAR->EAR.
 
re:
<< There's plenty of software out there to protect the privacy of our
e-mail communications, but I don't recall ever seeing any commercially
produced phone scramblers. This seems a bit odd on the face of it.
Maybe a gap in the market! If one were to set about designing such a
device (and its unscrambling counterpart for the remote phone) how
would one go about it? How might such a device be implemented? Just
curious to get a mental outline/block diagram for such a system....
In the late 80s or so there were a number of voice scramblers unsuccessfully
market, touted mainly for cellphone use, and acoustic coupled. There wasn't
much of a market and I could buy them at my local electronics wholesale outlet
for junk prices.
 
On Mon, 08 Nov 2004 13:32:17 +0000, Paul Burridge
<pb@notthisbit.osiris1.co.uk> wrote:

There's plenty of software out there to protect the privacy of our
e-mail communications, but I don't recall ever seeing any commercially
produced phone scramblers. This seems a bit odd on the face of it.
Maybe a gap in the market! If one were to set about designing such a
device (and its unscrambling counterpart for the remote phone) how
would one go about it? How might such a device be implemented? Just
curious to get a mental outline/block diagram for such a system....

Thanks,

p
Have a look at
http://www.transcrypt.com/
designed for two way radios but the principles are the same.

Early version were straight frequency inversion (or rotation around a
carrier of approx 1.5KHz). Later ones used a changing carrier
frequency in a pseudo-random sequence. More complex ones now split
the audio into a number of "bands" and the rearrange them, either in a
fixed sequence or again in a pseudo-random sequence.

Alan

++++++++++++++++++++++++++++++++++++++++++
Jenal Communications
Manufacturers and Suppliers of HF Selcall
P O Box 1108, Morley, WA, 6943
Tel: +61 8 9370 5533 Fax +61 8 9467 6146
Web Site: http://www.jenal.com
e-mail: http://www.jenal.com/?p=1
++++++++++++++++++++++++++++++++++++++++++
 
Rich The Philosophizer wrote:

A millennium or so ago, I saw a project in Popular Somethingorother,
where they just used a ring modulater on either end, and an agreed-on
carrier.
That's only useful if you use your ring to talk down the telephone. And
before you start...
 
done that, been there.
simple double balanced mixer using
diodes,transformers and 3.5 Osc using
the lower side band which generates
inverse audio.


Paul Burridge wrote:

There's plenty of software out there to protect the privacy of our
e-mail communications, but I don't recall ever seeing any commercially
produced phone scramblers. This seems a bit odd on the face of it.
Maybe a gap in the market! If one were to set about designing such a
device (and its unscrambling counterpart for the remote phone) how
would one go about it? How might such a device be implemented? Just
curious to get a mental outline/block diagram for such a system....

Thanks,

p
 
Jamie wrote:
done that, been there.
simple double balanced mixer using
diodes,transformers and 3.5 Osc using
the lower side band which generates
inverse audio.


Paul Burridge wrote:

There's plenty of software out there to protect the privacy of our
e-mail communications, but I don't recall ever seeing any commercially
produced phone scramblers. This seems a bit odd on the face of it.
Maybe a gap in the market! If one were to set about designing such a
device (and its unscrambling counterpart for the remote phone) how
would one go about it? How might such a device be implemented? Just
curious to get a mental outline/block diagram for such a system....

Thanks,

p


Hey, it's because it's plain illegal.
Now if you want encrypted phone conversations there's a nice piece of SW
out there, called skype.
I recommend.

;)
 
Patrick posted:

<< Jamie wrote:
done that, been there.
simple double balanced mixer using
diodes,transformers and 3.5 Osc using
the lower side band which generates
inverse audio.


Paul Burridge wrote:

There's plenty of software out there to protect the privacy of our
e-mail communications, but I don't recall ever seeing any commercially
produced phone scramblers. This seems a bit odd on the face of it.
Maybe a gap in the market! If one were to set about designing such a
device (and its unscrambling counterpart for the remote phone) how
would one go about it? How might such a device be implemented? Just
curious to get a mental outline/block diagram for such a system....

Thanks,

p


Hey, it's because it's plain illegal.
(snip)

Since when? I can encrypt my telephone calls if I wish, and it's nobodys
business but the person I'm talking with. Now, if you are talking about
France, then perhaps it is illegal. Wouldn't surprise me. Is your ISP address
telling a fib?


Don
 
Dbowey > /dev/null :

Since when? I can encrypt my telephone calls if I wish, and it's nobodys
business but the person I'm talking with. Now, if you are talking about
France, then perhaps it is illegal. Wouldn't surprise me. Is your ISP address
telling a fib?
Here in Brazil we can (in theory) have encryption for cellular phone calls.

Once, there was a program that ran in one of those 'smart phones' (PDA +
cellular phone), that allowed you to call someone that also had the program and
do encrypted communications.

I haven't used it (smartphones are very expensive), but the cellular phone
company said that there wasn't any problem.

So, at least for cellular phone, AFAIK and IMHO it's not illegal to do
scrambling.

[]s
--
Chaos MasterŽ, posting from Brazil.
"It's not what it seems, not what you think. No, I must be dreaming."

http://marreka.no-ip.com | http://tinyurl.com/46vru
http://renan182.no-ip.org | http://marreka.blogspot.com (in Portuguese)
 
Digital Telephone scrambling is normal in the UK. It's part of the service. You
can't switch it off.

Gibbo
 
On 14 Nov 2004 22:55:39 GMT, chrisgibbogibson@aol.com
(ChrisGibboGibson) wrote:

Digital Telephone scrambling is normal in the UK. It's part of the service. You
can't switch it off.
Indeed, but the GOVERNMENT have a key to unlock it. What are you going
to do to retain your right to privacy? I don't want some spook jerkin'
off while I'm talking to my girlfriend - when I get one, I mean.
--

"What is now proved was once only imagin'd." - William Blake, 1793.
 

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