PSTN Authentication

D

Don Y

Guest
Hi,

I'm looking for ideas on how to provide (reasonable) authentication
over the PSTN. CID is too readily spoofed (usually by the very folks
that you want to "avoid"!).

A simple scheme might be to use unique identifiers from a large, sparse
ID-space -- providing the ID (DTMF or voice) would provide an indication
of the user. This has the advantage of being tied to a USER and not
a line/device. It sucks because it requires users to remember a
specific ID (for *each* party that they intend to call!)

A more elaborate scheme could rely on voice-print identification.
Ideally, obtaining a voice print from the party at some "registration"
time. To address "playback" attacks, the caller could be required to
make a statement indicated at the time of the call.

Any sort of call-back scheme falls down because of the possibility
of theft of service that it presents. (It also assumes the user
would be at a fixed "location")

Then, there are a whole set of "class identification" schemes (i.e.,
where the type of caller is needed, not the actual identity -- robocall
prevention, etc.). I figure anything interactive will beat them
("Press <digit_determined_at_time_of_call> now", "How much is <digit1>
plus <digit2>?" etc.)

My goal, here, is to provide an "automated attendant" function -- sort
of an "electronic secretary" that can screen calls intelligently:
- route all calls from political parties to /dev/null
- don't even let the phone *ring* if it's a telemarketer
- when I am asleep, take a message from any of these callers
- whenever <someone> calls, *find* me!
- if Bob calls, tell him I am on my way
- if *I* call, give me access to <whatever>
etc.

Obviously, the cost (inconvenience?) to the caller can vary as the
"value" of the service he/she is expecting.

Thx,
--don
 
On Sat, 13 Sep 2014 11:57:59 -0700, Don Y <this@isnotme.com> Gave us:

A more elaborate scheme could rely on voice-print identification.
Ideally, obtaining a voice print from the party at some "registration"

Except that POTS audible resolution is crap, and any voice print
analysis data would also therefore be crap.
 
On Sat, 13 Sep 2014 11:57:59 -0700, Don Y <this@isnotme.com> wrote:

Hi,

I'm looking for ideas on how to provide (reasonable) authentication
over the PSTN. CID is too readily spoofed (usually by the very folks
that you want to "avoid"!).

A simple scheme might be to use unique identifiers from a large, sparse
ID-space -- providing the ID (DTMF or voice) would provide an indication
of the user. This has the advantage of being tied to a USER and not
a line/device. It sucks because it requires users to remember a
specific ID (for *each* party that they intend to call!)

A more elaborate scheme could rely on voice-print identification.
Ideally, obtaining a voice print from the party at some "registration"
time. To address "playback" attacks, the caller could be required to
make a statement indicated at the time of the call.

Any sort of call-back scheme falls down because of the possibility
of theft of service that it presents. (It also assumes the user
would be at a fixed "location")

Then, there are a whole set of "class identification" schemes (i.e.,
where the type of caller is needed, not the actual identity -- robocall
prevention, etc.). I figure anything interactive will beat them
("Press <digit_determined_at_time_of_call> now", "How much is <digit1
plus <digit2>?" etc.)

My goal, here, is to provide an "automated attendant" function -- sort
of an "electronic secretary" that can screen calls intelligently:
- route all calls from political parties to /dev/null
- don't even let the phone *ring* if it's a telemarketer
- when I am asleep, take a message from any of these callers
- whenever <someone> calls, *find* me!
- if Bob calls, tell him I am on my way
- if *I* call, give me access to <whatever
etc.

Obviously, the cost (inconvenience?) to the caller can vary as the
"value" of the service he/she is expecting.

Thx,
--don

I'd settle for a reasonable-cost system that required the caller to
enter some 4-digit code such that robo-calls would be snuffed... I'm
tiring of the crap.

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
On 09/13/2014 08:57 PM, Don Y wrote:
Hi,

I'm looking for ideas on how to provide (reasonable) authentication
over the PSTN. CID is too readily spoofed (usually by the very folks
that you want to "avoid"!).

A simple scheme might be to use unique identifiers from a large, sparse
ID-space -- providing the ID (DTMF or voice) would provide an indication
of the user. This has the advantage of being tied to a USER and not
a line/device. It sucks because it requires users to remember a
specific ID (for *each* party that they intend to call!)

A more elaborate scheme could rely on voice-print identification.
Ideally, obtaining a voice print from the party at some "registration"
time. To address "playback" attacks, the caller could be required to
make a statement indicated at the time of the call.

Any sort of call-back scheme falls down because of the possibility
of theft of service that it presents. (It also assumes the user
would be at a fixed "location")

Then, there are a whole set of "class identification" schemes (i.e.,
where the type of caller is needed, not the actual identity -- robocall
prevention, etc.). I figure anything interactive will beat them
("Press <digit_determined_at_time_of_call> now", "How much is <digit1
plus <digit2>?" etc.)

My goal, here, is to provide an "automated attendant" function -- sort
of an "electronic secretary" that can screen calls intelligently:
- route all calls from political parties to /dev/null
- don't even let the phone *ring* if it's a telemarketer
- when I am asleep, take a message from any of these callers
- whenever <someone> calls, *find* me!
- if Bob calls, tell him I am on my way
- if *I* call, give me access to <whatever
etc.

Obviously, the cost (inconvenience?) to the caller can vary as the
"value" of the service he/she is expecting.

Thx,
--don

<https://en.wikipedia.org/wiki/Challenge%E2%80%93response_authentication>

The challenge is different every time, there are multiple valid
responses for each challenge. Anyone eavesdropping has a really hard
time guessing...

(the nerd on 'NUMBERS' said it was cool, so who am I to object)
 
On 9/13/2014 6:26 PM, Johann Klammer wrote:
On 09/13/2014 08:57 PM, Don Y wrote:
Hi,

I'm looking for ideas on how to provide (reasonable) authentication
over the PSTN. CID is too readily spoofed (usually by the very folks
that you want to "avoid"!).

A simple scheme might be to use unique identifiers from a large, sparse
ID-space -- providing the ID (DTMF or voice) would provide an indication
of the user. This has the advantage of being tied to a USER and not
a line/device. It sucks because it requires users to remember a
specific ID (for *each* party that they intend to call!)

A more elaborate scheme could rely on voice-print identification.
Ideally, obtaining a voice print from the party at some "registration"
time. To address "playback" attacks, the caller could be required to
make a statement indicated at the time of the call.

Then, there are a whole set of "class identification" schemes (i.e.,
where the type of caller is needed, not the actual identity -- robocall
prevention, etc.). I figure anything interactive will beat them
("Press <digit_determined_at_time_of_call> now", "How much is <digit1
plus <digit2>?" etc.)

My goal, here, is to provide an "automated attendant" function -- sort
of an "electronic secretary" that can screen calls intelligently:
- route all calls from political parties to /dev/null
- don't even let the phone *ring* if it's a telemarketer
- when I am asleep, take a message from any of these callers
- whenever <someone> calls, *find* me!
- if Bob calls, tell him I am on my way
- if *I* call, give me access to <whatever
etc.

https://en.wikipedia.org/wiki/Challenge%E2%80%93response_authentication

The challenge is different every time, there are multiple valid
responses for each challenge. Anyone eavesdropping has a really hard
time guessing...

(the nerd on 'NUMBERS' said it was cool, so who am I to object)

Note that the challenge can be unique to each caller. For example,
having an inclination that "Penny" is calling (by characterization
of her speech pattern -- or, because she provided the *three* digit
code that has been assigned to Penny), you can query her as to the
name of her firstborn child; the weather in her known location (which
you can independently verify via a trusted source), etc.

And, it might NOT take the (typical) form of a "shared secret"!
You could, for example, prompt her to speak a particular set of
words that allow you to more accurately characterize her vowel
sounds, etc. This would defeat a playback attack because the
caller wouldn't know *which* words he/she would be asked to speak!
(there are ways around this but the bar gets set a lot higher)
 
On 9/13/14, 1:57 PM, Don Y wrote:
Hi,

I'm looking for ideas on how to provide (reasonable) authentication
over the PSTN. CID is too readily spoofed (usually by the very folks
that you want to "avoid"!).

A simple scheme might be to use unique identifiers from a large, sparse
ID-space -- providing the ID (DTMF or voice) would provide an indication
of the user. This has the advantage of being tied to a USER and not
a line/device. It sucks because it requires users to remember a
specific ID (for *each* party that they intend to call!)

A more elaborate scheme could rely on voice-print identification.
Ideally, obtaining a voice print from the party at some "registration"
time. To address "playback" attacks, the caller could be required to
make a statement indicated at the time of the call.

Any sort of call-back scheme falls down because of the possibility
of theft of service that it presents. (It also assumes the user
would be at a fixed "location")

Then, there are a whole set of "class identification" schemes (i.e.,
where the type of caller is needed, not the actual identity -- robocall
prevention, etc.). I figure anything interactive will beat them
("Press <digit_determined_at_time_of_call> now", "How much is <digit1
plus <digit2>?" etc.)

My goal, here, is to provide an "automated attendant" function -- sort
of an "electronic secretary" that can screen calls intelligently:
- route all calls from political parties to /dev/null
- don't even let the phone *ring* if it's a telemarketer
- when I am asleep, take a message from any of these callers
- whenever <someone> calls, *find* me!
- if Bob calls, tell him I am on my way
- if *I* call, give me access to <whatever
etc.

Obviously, the cost (inconvenience?) to the caller can vary as the
"value" of the service he/she is expecting.

Thx,
--don
Hi Don,

Use a one-time-pad for challenge-response. Give each caller their own
pad. If it's generated using a good random source, and the responses are
not re-used, it will keep out even the NSA. That is, assuming they don't
steal your physical copy of the pad, or just make you give it to them
through coercion. I briefly considered doing something like this as a
commercial product, but then I realized all of my customers would be
drug dealers.

ChesterW
 
On 9/13/2014 1:57 PM, Don Y wrote:
Hi,

I'm looking for ideas on how to provide (reasonable) authentication
over the PSTN. CID is too readily spoofed (usually by the very folks
that you want to "avoid"!).

A simple scheme might be to use unique identifiers from a large, sparse
ID-space -- providing the ID (DTMF or voice) would provide an indication
of the user. This has the advantage of being tied to a USER and not
a line/device. It sucks because it requires users to remember a
specific ID (for *each* party that they intend to call!)

A more elaborate scheme could rely on voice-print identification.
Ideally, obtaining a voice print from the party at some "registration"
time. To address "playback" attacks, the caller could be required to
make a statement indicated at the time of the call.

Any sort of call-back scheme falls down because of the possibility
of theft of service that it presents. (It also assumes the user
would be at a fixed "location")

Then, there are a whole set of "class identification" schemes (i.e.,
where the type of caller is needed, not the actual identity -- robocall
prevention, etc.). I figure anything interactive will beat them
("Press <digit_determined_at_time_of_call> now", "How much is <digit1
plus <digit2>?" etc.)

My goal, here, is to provide an "automated attendant" function -- sort
of an "electronic secretary" that can screen calls intelligently:
- route all calls from political parties to /dev/null
- don't even let the phone *ring* if it's a telemarketer
- when I am asleep, take a message from any of these callers
- whenever <someone> calls, *find* me!
- if Bob calls, tell him I am on my way
- if *I* call, give me access to <whatever
etc.

Obviously, the cost (inconvenience?) to the caller can vary as the
"value" of the service he/she is expecting.

Thx,
--don

When your product is available, let us know. I will be interested.
 
On 9/14/2014 12:48 AM, ChesterW wrote:
On 9/13/14, 1:57 PM, Don Y wrote:
Hi,

I'm looking for ideas on how to provide (reasonable) authentication
over the PSTN. CID is too readily spoofed (usually by the very folks
that you want to "avoid"!).

A simple scheme might be to use unique identifiers from a large, sparse
ID-space -- providing the ID (DTMF or voice) would provide an indication
of the user. This has the advantage of being tied to a USER and not
a line/device. It sucks because it requires users to remember a
specific ID (for *each* party that they intend to call!)

A more elaborate scheme could rely on voice-print identification.
Ideally, obtaining a voice print from the party at some "registration"
time. To address "playback" attacks, the caller could be required to
make a statement indicated at the time of the call.

Any sort of call-back scheme falls down because of the possibility
of theft of service that it presents. (It also assumes the user
would be at a fixed "location")

Then, there are a whole set of "class identification" schemes (i.e.,
where the type of caller is needed, not the actual identity -- robocall
prevention, etc.). I figure anything interactive will beat them
("Press <digit_determined_at_time_of_call> now", "How much is <digit1
plus <digit2>?" etc.)

My goal, here, is to provide an "automated attendant" function -- sort
of an "electronic secretary" that can screen calls intelligently:
- route all calls from political parties to /dev/null
- don't even let the phone *ring* if it's a telemarketer
- when I am asleep, take a message from any of these callers
- whenever <someone> calls, *find* me!
- if Bob calls, tell him I am on my way
- if *I* call, give me access to <whatever
etc.

Obviously, the cost (inconvenience?) to the caller can vary as the
"value" of the service he/she is expecting.

Thx,
--don
Hi Don,

Use a one-time-pad for challenge-response. Give each caller their own
pad. If it's generated using a good random source, and the responses are
not re-used, it will keep out even the NSA. That is, assuming they don't
steal your physical copy of the pad, or just make you give it to them
through coercion. I briefly considered doing something like this as a
commercial product, but then I realized all of my customers would be
drug dealers.

Not a 1 time pad, a rolling code. It would be far too easy to mess up
using the 1 time pad. It might be something to program into a smart
phone. Then it could be a one time pad, secure until your phone is hacked.

Geez. You guys really do over think a simple problem.

--

Rick
 
On 9/14/2014 12:38 AM, Don Y wrote:
On 9/13/2014 6:59 PM, rickman wrote:
On 9/13/2014 2:57 PM, Don Y wrote:
Hi,

I'm looking for ideas on how to provide (reasonable) authentication
over the PSTN. CID is too readily spoofed (usually by the very folks
that you want to "avoid"!).

My goal, here, is to provide an "automated attendant" function -- sort
of an "electronic secretary" that can screen calls intelligently:
- route all calls from political parties to /dev/null
- don't even let the phone *ring* if it's a telemarketer
- when I am asleep, take a message from any of these callers
- whenever <someone> calls, *find* me!
- if Bob calls, tell him I am on my way
- if *I* call, give me access to <whatever
etc.

Obviously, the cost (inconvenience?) to the caller can vary as the
"value" of the service he/she is expecting.

I've considered doing this in a way that would not be rude or even
obvious. Being a business line, my answering machine should appear to be
a business. Your suggestions above are basically what I came up with. A
short intro saying "Hello, you have reached Arius, Inc. Please press xy
to speak with a representative."

"xy" has to be more than a single digit as a robocaller could
"press" 1234567890.

Duh! That is why I wrote xy and not x. I have received robocalls that
automatically send one or even two DTMF tones. I think they are
shooting for the most common single button press codes.


If "xy" was canned (or even The Default) for The Device, then there
would be a high probability of a robocaller "guessing" it.

No, there is a *low* probability of it being guessed. 1 in 100 to be
exact.


You also have to allow for it to be spoken in case the caller can't
emit DTMF during the call.

I don't. I can't remember the last time I couldn't send a DTMF tone.


This will stop the robo calls.

It will stop the calls whereby a robot dialer AND TALKER deliver the
message. But, if the dialer is automated and hands off the call
to a human once the circuit is complete (answered), then the human
can listen to your message and comply.

I find very few of those. They usually listen for someone answering the
phone and many start their own blurb before asking you to wait for the
handoff. Do you really need to stop all the annoying calls or just get
the 98th percentile?


As you
suggest only then will the phone actually ring, not the phone really as
that requires more expensive circuitry to generate a ring voltage.
Rather this unit would sound its own ringer. That might not be so great
with my cordless phone, but the unit's ringer can sound in multiple
location so I won't miss it.

I've never received a political call that wasn't robo so that is dealt
with. I'm not sure how the unit will know you are asleep... If the phone
is not answered it will pass the call to the regular answering
machine... which will require the ringer circuit, darn!

If I'm in my bedroom and haven't moved from there for 10 minutes, the
chances are: I'm asleep!

Similarly, if I am in the bathroom, I *probably* don't want to take the
call.

If I'm in the back yard, I probably don't want to be disturbed for
"just anyone".

And, I sure as hell don't want *every* phone ringing if it knows
I'm "at" a particular phone!

I think you are designing a secretary. How does your phone know where
you are?


Regardless, the "automated attendant" (need a better term :< ) is
desirable. Letting the phone ring and eventually falling back to
an answering machine (or any other secondary processing) is a poor
compromise, IMO.

I agree.


Find you? lol I guess you can train the dog to come get you when the
ultrasonic ringer sounds. Won't work so well if you are out in the car
somewhere...

If I am not "in the house", it can deduce if I'm in the back yard
or "somewhere out front" (based on the manner by which I left the
building. If it suspects I am nearby, it can attempt to alert me
"page"). If it sees the cordless phone has been taken from its
base, it an assume I am "within the neighborhood" and ring that
"extension". If/when I pick up, it can *announce* the caller to
me thereby giving me an opportunity to instruct it to "take a
message" (or, record a voice message to dispatch AS IF it had
been left or that caller).

[Think: good secretary!]

If I left the house via the garage, the garage door opened AND closed
and the car is not within, then it can assume I have driven off.
(of course, if I took the cordless phone with me, then I am implicitly
telling "it" that I expect to be reachable ON that phone -- give it
a try, I may just have driven to another residence in the subdvision)

You do this a lot in your posts. You start going off on what appear to
be tangents because you have not explained most of what is going on. So
you are going to wire all your doors (and windows so the system knows if
you have used a fire escape and call 911)? What else will this system
monitor that you haven't mentioned? I think this is going to be a
multi-thousand dollar system by the time it is done.


If Bob calls answer the phone and tell him you are on the way yourself!

I'm not *at* the phone that Bob has called! Or, I *may* be yet don't
want to get drawn into a conversation with Bob which will delay
everything *else* I may have planned.

[Again, think: good secretary!]

You mean mind reader?


If you are calling you know to press "abcd" before the machine prompts
you for "xy".

Too easy for someone to notice. I much prefer spending extra effort
"training" it to my voice and then engaging in an authentication dialog
(even the number of words required for me to command it to perform a
specific action increases the chance of it verifying *my* speech
characteristics)

Good luck. I think this will be some time showing up.

--

Rick
 
On 2014-09-14, rickman <gnuarm@gmail.com> wrote:
On 9/13/2014 2:57 PM, Don Y wrote:

I've considered doing this in a way that would not be rude or even
obvious. Being a business line, my answering machine should appear to
be a business. Your suggestions above are basically what I came up
with. A short intro saying "Hello, you have reached Arius, Inc. Please
press xy to speak with a representative." This will stop the robo
calls. As you suggest only then will the phone actually ring, not the
phone really as that requires more expensive circuitry to generate a
ring voltage. Rather this unit would sound its own ringer. That might
not be so great with my cordless phone, but the unit's ringer can sound
in multiple location so I won't miss it.

Ring gemerators can be had for about 20 bucks, (buy a "FXS" VOIP adaptor on
amazon)

I've never received a political call that wasn't robo so that is dealt
with. I'm not sure how the unit will know you are asleep... If the
phone is not answered it will pass the call to the regular answering
machine... which will require the ringer circuit, darn!

Find you? lol I guess you can train the dog to come get you when the
ultrasonic ringer sounds. Won't work so well if you are out in the car
somewhere...

If Bob calls answer the phone and tell him you are on the way yourself!

If you are calling you know to press "abcd" before the machine prompts
you for "xy".

Tell bob your extension is "abcd" and to dial it as soon as the voice
starts.

I would build this but I have other things on my list.

--
umop apisdn


--- news://freenews.netfront.net/ - complaints: news@netfront.net ---
 
On 9/13/2014 9:48 PM, ChesterW wrote:
On 9/13/14, 1:57 PM, Don Y wrote:

I'm looking for ideas on how to provide (reasonable) authentication
over the PSTN. CID is too readily spoofed (usually by the very folks
that you want to "avoid"!).

A simple scheme might be to use unique identifiers from a large, sparse
ID-space -- providing the ID (DTMF or voice) would provide an indication
of the user. This has the advantage of being tied to a USER and not
a line/device. It sucks because it requires users to remember a
specific ID (for *each* party that they intend to call!)

A more elaborate scheme could rely on voice-print identification.
Ideally, obtaining a voice print from the party at some "registration"
time. To address "playback" attacks, the caller could be required to
make a statement indicated at the time of the call.

Use a one-time-pad for challenge-response. Give each caller their own
pad. If it's generated using a good random source, and the responses are
not re-used, it will keep out even the NSA. That is, assuming they don't
steal your physical copy of the pad, or just make you give it to them
through coercion. I briefly considered doing something like this as a
commercial product, but then I realized all of my customers would be
drug dealers.

I think that puts too much of a burden on callers. And, requires a
fair bit of "set up" for each caller.

Consider someone that calls "seldom". They wouldn't want to be
bothered keeping track of where they are in the pad -- even a
simple "N digit ID" would probably annoy them.

I think any solution has to "feel" natural. The "good secretary"
model, I think, is worth considering in developing a solution.

Your "secretary" typically recognizes the voice of frequent callers.
Or, their mannerisms. Even for infrequent callers, she allows them to
identify themselves in a "natural" manner: "Hi, this is Bob".
Perhaps during their initial banter, she refines her idea of who
"Bob" actually *is* ("Gee, you don't SOUND like Bob!")

She can do this because she's observant *and* exposed to all of
this dialog (imagine how she would fare if she was "first day on
the job!")

If the phone can *listen* to your (human) dialog with a particular
party, it can conceivably get a good deal of training information
regarding how *that* particular caller speaks. If, some months
later, it encounters the same individual, it can engage the caller
in "seemingly" harmless banter to extract more voice samples from
the caller. Even things like, "What number are you calling from,
Bob?" will generate more input for analysis ("Gee, that's not the
number I have on file for you! Would you like me to update our
records? Or, are you just calling from this number temporarily?")

Of course, of the caller is trying to get the attendant to perform
some "privileged" action ("Please wake him for me!"), then it seems
"fair" to burden the caller a bit more (to get a more certain
identification).

The advantage of this sort of scheme is that it is portable and
doesn't require the caller to do much more than he/she would do
if "forced" to interact with your "secretary"... I.e., it *feels*
natural (instead of "please enter the 12 digit identifier that
has been assigned to you. Use '#' to start over, '*' to delete
the previous digit...")
 
On 9/13/2014 9:47 PM, John S wrote:

> When your product is available, let us know. I will be interested.

Sorry, John, I have no desire to be a "manufacturer".

OTOH, perhaps someone else will take the design and commercialize it.
Amazing to think "smart" phones wouldn't already have such a feature...
 
On 9/13/2014 6:59 PM, rickman wrote:
On 9/13/2014 2:57 PM, Don Y wrote:
Hi,

I'm looking for ideas on how to provide (reasonable) authentication
over the PSTN. CID is too readily spoofed (usually by the very folks
that you want to "avoid"!).

My goal, here, is to provide an "automated attendant" function -- sort
of an "electronic secretary" that can screen calls intelligently:
- route all calls from political parties to /dev/null
- don't even let the phone *ring* if it's a telemarketer
- when I am asleep, take a message from any of these callers
- whenever <someone> calls, *find* me!
- if Bob calls, tell him I am on my way
- if *I* call, give me access to <whatever
etc.

Obviously, the cost (inconvenience?) to the caller can vary as the
"value" of the service he/she is expecting.

I've considered doing this in a way that would not be rude or even
obvious. Being a business line, my answering machine should appear to be
a business. Your suggestions above are basically what I came up with. A
short intro saying "Hello, you have reached Arius, Inc. Please press xy
to speak with a representative."

"xy" has to be more than a single digit as a robocaller could
"press" 1234567890.

If "xy" was canned (or even The Default) for The Device, then there
would be a high probability of a robocaller "guessing" it.

You also have to allow for it to be spoken in case the caller can't
emit DTMF during the call.

> This will stop the robo calls.

It will stop the calls whereby a robot dialer AND TALKER deliver the
message. But, if the dialer is automated and hands off the call
to a human once the circuit is complete (answered), then the human
can listen to your message and comply.

As you
suggest only then will the phone actually ring, not the phone really as
that requires more expensive circuitry to generate a ring voltage.
Rather this unit would sound its own ringer. That might not be so great
with my cordless phone, but the unit's ringer can sound in multiple
location so I won't miss it.

I've never received a political call that wasn't robo so that is dealt
with. I'm not sure how the unit will know you are asleep... If the phone
is not answered it will pass the call to the regular answering
machine... which will require the ringer circuit, darn!

If I'm in my bedroom and haven't moved from there for 10 minutes, the
chances are: I'm asleep!

Similarly, if I am in the bathroom, I *probably* don't want to take the
call.

If I'm in the back yard, I probably don't want to be disturbed for
"just anyone".

And, I sure as hell don't want *every* phone ringing if it knows
I'm "at" a particular phone!

Regardless, the "automated attendant" (need a better term :< ) is
desirable. Letting the phone ring and eventually falling back to
an answering machine (or any other secondary processing) is a poor
compromise, IMO.

Find you? lol I guess you can train the dog to come get you when the
ultrasonic ringer sounds. Won't work so well if you are out in the car
somewhere...

If I am not "in the house", it can deduce if I'm in the back yard
or "somewhere out front" (based on the manner by which I left the
building. If it suspects I am nearby, it can attempt to alert me
"page"). If it sees the cordless phone has been taken from its
base, it an assume I am "within the neighborhood" and ring that
"extension". If/when I pick up, it can *announce* the caller to
me thereby giving me an opportunity to instruct it to "take a
message" (or, record a voice message to dispatch AS IF it had
been left or that caller).

[Think: good secretary!]

If I left the house via the garage, the garage door opened AND closed
and the car is not within, then it can assume I have driven off.
(of course, if I took the cordless phone with me, then I am implicitly
telling "it" that I expect to be reachable ON that phone -- give it
a try, I may just have driven to another residence in the subdvision)

> If Bob calls answer the phone and tell him you are on the way yourself!

I'm not *at* the phone that Bob has called! Or, I *may* be yet don't
want to get drawn into a conversation with Bob which will delay
everything *else* I may have planned.

[Again, think: good secretary!]

If you are calling you know to press "abcd" before the machine prompts
you for "xy".

Too easy for someone to notice. I much prefer spending extra effort
"training" it to my voice and then engaging in an authentication dialog
(even the number of words required for me to command it to perform a
specific action increases the chance of it verifying *my* speech
characteristics)

> I would build this but I have other things on my list.
 
On 9/13/2014 1:55 PM, Jim Thompson wrote:
On Sat, 13 Sep 2014 11:57:59 -0700, Don Y<this@isnotme.com> wrote:

I'm looking for ideas on how to provide (reasonable) authentication
over the PSTN. CID is too readily spoofed (usually by the very folks
that you want to "avoid"!).

A simple scheme might be to use unique identifiers from a large, sparse
ID-space -- providing the ID (DTMF or voice) would provide an indication
of the user. This has the advantage of being tied to a USER and not
a line/device. It sucks because it requires users to remember a
specific ID (for *each* party that they intend to call!)

I'd settle for a reasonable-cost system that required the caller to
enter some 4-digit code such that robo-calls would be snuffed... I'm
tiring of the crap.

A true robot would be stymied by "Please press <digit> now".

A "telemarketer", OTOH, would not ("OK, I'll press that!").
(nowadays, it seems like a robot dials and hands off to a human
when the callee "answers")

If the <digit> was "canned" (i.e., the same for every/many instances of
this device), a robocaller could just blurt out the code unconditionally
to bypass that mechanism.

If it was a *single* changeable (or "random") digit, then pressing all
keys, sequentially, unconditionally, would eventually hit upon the
correct digit (i.e., you would have to allow perhaps *two* attempts
and REQUIRE no more than two before validating the input)

Any code that requires legitimate callers to remember it is an
inconvenience. If you could be assured a "timely" response by the
callee ("device"), I suspect you could program the code as a part
of the actual phone number -- just "delayed" (e.g., 555-1212%%%123456
where '%' forces an unconditional 1 second pause)

But, I want caller *identification*, not *just* "is this a human"...
 
On 9/13/2014 2:57 PM, Don Y wrote:
Hi,

I'm looking for ideas on how to provide (reasonable) authentication
over the PSTN. CID is too readily spoofed (usually by the very folks
that you want to "avoid"!).
....snip....
Then, there are a whole set of "class identification" schemes (i.e.,
where the type of caller is needed, not the actual identity -- robocall
prevention, etc.). I figure anything interactive will beat them
("Press <digit_determined_at_time_of_call> now", "How much is <digit1
plus <digit2>?" etc.)

My goal, here, is to provide an "automated attendant" function -- sort
of an "electronic secretary" that can screen calls intelligently:
- route all calls from political parties to /dev/null
- don't even let the phone *ring* if it's a telemarketer
- when I am asleep, take a message from any of these callers
- whenever <someone> calls, *find* me!
- if Bob calls, tell him I am on my way
- if *I* call, give me access to <whatever
etc.

Obviously, the cost (inconvenience?) to the caller can vary as the
"value" of the service he/she is expecting.

I've considered doing this in a way that would not be rude or even
obvious. Being a business line, my answering machine should appear to
be a business. Your suggestions above are basically what I came up
with. A short intro saying "Hello, you have reached Arius, Inc. Please
press xy to speak with a representative." This will stop the robo
calls. As you suggest only then will the phone actually ring, not the
phone really as that requires more expensive circuitry to generate a
ring voltage. Rather this unit would sound its own ringer. That might
not be so great with my cordless phone, but the unit's ringer can sound
in multiple location so I won't miss it.

I've never received a political call that wasn't robo so that is dealt
with. I'm not sure how the unit will know you are asleep... If the
phone is not answered it will pass the call to the regular answering
machine... which will require the ringer circuit, darn!

Find you? lol I guess you can train the dog to come get you when the
ultrasonic ringer sounds. Won't work so well if you are out in the car
somewhere...

If Bob calls answer the phone and tell him you are on the way yourself!

If you are calling you know to press "abcd" before the machine prompts
you for "xy".

I would build this but I have other things on my list.

--

Rick
 
On 9/13/2014 12:21 PM, DecadentLinuxUserNumeroUno wrote:
On Sat, 13 Sep 2014 11:57:59 -0700, Don Y<this@isnotme.com> Gave us:


A more elaborate scheme could rely on voice-print identification.
Ideally, obtaining a voice print from the party at some "registration"

Except that POTS audible resolution is crap, and any voice print
analysis data would also therefore be crap.

Apparently, it is good enough for (e.g.) *banks* to rely on it (at least
as a first-stage "convenience" feature):

<https://wealth.barclays.com/en_gb/internationalwealth/manage-your-money/banking-on-the-power-of-speech.html>

Note that you don't have to treat it as an authoritative indicator!
Rather, you can use this in conjunction with other "data" to decrease
the chance of a false positive to a level appropriate for the level
of "access" you are granting.

E.g., every scheme has some level of confidence/uncertainty: a single
digit "access code" has a 10% chance of being guessed correctly; two
digits are 1%. Of course, if a caller can freely *retry* callingand
trying a *different* code...

Similarly, CID might *not* be spoofed so disregarding it as an
input is foolish. (RELYING on it might be, though!)
 
On 9/13/2014 10:20 PM, rickman wrote:
On 9/14/2014 12:38 AM, Don Y wrote:
On 9/13/2014 6:59 PM, rickman wrote:
On 9/13/2014 2:57 PM, Don Y wrote:
Hi,

I'm looking for ideas on how to provide (reasonable) authentication
over the PSTN. CID is too readily spoofed (usually by the very folks
that you want to "avoid"!).

My goal, here, is to provide an "automated attendant" function -- sort
of an "electronic secretary" that can screen calls intelligently:
- route all calls from political parties to /dev/null
- don't even let the phone *ring* if it's a telemarketer
- when I am asleep, take a message from any of these callers
- whenever <someone> calls, *find* me!
- if Bob calls, tell him I am on my way
- if *I* call, give me access to <whatever
etc.

Obviously, the cost (inconvenience?) to the caller can vary as the
"value" of the service he/she is expecting.

I've considered doing this in a way that would not be rude or even
obvious. Being a business line, my answering machine should appear to be
a business. Your suggestions above are basically what I came up with. A
short intro saying "Hello, you have reached Arius, Inc. Please press xy
to speak with a representative."

"xy" has to be more than a single digit as a robocaller could
"press" 1234567890.

Duh! That is why I wrote xy and not x. I have received robocalls that
automatically send one or even two DTMF tones. I think they are shooting
for the most common single button press codes.

If "xy" was canned (or even The Default) for The Device, then there
would be a high probability of a robocaller "guessing" it.

No, there is a *low* probability of it being guessed. 1 in 100 to be exact.

Read what I wrote:
"If "xy" was canned (or even The Default) for The Device..."
i.e., if EVERY instance of The Device had "xy" HARDCODED to be "21",
then all a robocaller needs to do is *try* "21" when it encounters
a device that it SUSPECTS may be this type.

Similarly, if "xy" is The (Factory) Default, then it is highly likely
that many such instances will be encountered that will still have the
code set to the factory default.

You also have to allow for it to be spoken in case the caller can't
emit DTMF during the call.

I don't. I can't remember the last time I couldn't send a DTMF tone.

My parents have a *dial* telephone.

Do all VoIP systems alow tones to be generated by the station set?
Even after the call has been placed?

If you "borrow" the phone at your MD/Dentist/Retail/etc. location,
do they *hand* you the phone? Or, dial for you and hand you the
*receiver* (because the phone is located someplace convenient for
*them* to access, not "guests"/visiors)?

If you are driving, do you want to again bring your eyes to the
phone to type in a code number?

[And, why are so many VRT systems replacing the old DTMF interaction
with voice response?]

DTMF is for the convenience of the DEVICE implementer, not the user.

This will stop the robo calls.

It will stop the calls whereby a robot dialer AND TALKER deliver the
message. But, if the dialer is automated and hands off the call
to a human once the circuit is complete (answered), then the human
can listen to your message and comply.

I find very few of those. They usually listen for someone answering the
phone and many start their own blurb before asking you to wait for the
handoff. Do you really need to stop all the annoying calls or just get
the 98th percentile?

Most robocalls, here, wait for the callee to answer. Then, within a
second -- perhaps two -- you can hear a human come on the line.They have
obviously designed their systems for this handoff to be very
quick -- much longer than two seconds and I suspect folks would be in
the process of hanging up ("crank call") before they got on the line.

How many calls do you expect your secretary to let "slip through"?

As you
suggest only then will the phone actually ring, not the phone really as
that requires more expensive circuitry to generate a ring voltage.
Rather this unit would sound its own ringer. That might not be so great
with my cordless phone, but the unit's ringer can sound in multiple
location so I won't miss it.

I've never received a political call that wasn't robo so that is dealt
with. I'm not sure how the unit will know you are asleep... If the phone
is not answered it will pass the call to the regular answering
machine... which will require the ringer circuit, darn!

If I'm in my bedroom and haven't moved from there for 10 minutes, the
chances are: I'm asleep!

Similarly, if I am in the bathroom, I *probably* don't want to take the
call.

If I'm in the back yard, I probably don't want to be disturbed for
"just anyone".

And, I sure as hell don't want *every* phone ringing if it knows
I'm "at" a particular phone!

I think you are designing a secretary. How does your phone know where
you are?

Not germane to the question at hand. Rather, an example of how you can
*use* authentication in a larger context.

How does *your* secretary know where you are? Is she seated outside
your office door so she can watch you come and go? Do you regularly
tell her where you will be when leaving? Do you work in an "open"
floorplan so she can see clear across the building and notice you
chatting with the VP 60 ft away? Do you maintain a "pegboard" (or
other notification system) to indicate that you are out of the office?
Does she know about the 12:30 staff meeting (and naturally *assume*
you are there)? Does she know your habits well enough to predict
where you are *likely* to be?

[Assume a client had charged you with designing a system that could
track and report your "location". Could you do it?]

Find you? lol I guess you can train the dog to come get you when the
ultrasonic ringer sounds. Won't work so well if you are out in the car
somewhere...

If I am not "in the house", it can deduce if I'm in the back yard
or "somewhere out front" (based on the manner by which I left the
building. If it suspects I am nearby, it can attempt to alert me
"page"). If it sees the cordless phone has been taken from its
base, it an assume I am "within the neighborhood" and ring that
"extension". If/when I pick up, it can *announce* the caller to
me thereby giving me an opportunity to instruct it to "take a
message" (or, record a voice message to dispatch AS IF it had
been left or that caller).

[Think: good secretary!]

If I left the house via the garage, the garage door opened AND closed
and the car is not within, then it can assume I have driven off.
(of course, if I took the cordless phone with me, then I am implicitly
telling "it" that I expect to be reachable ON that phone -- give it
a try, I may just have driven to another residence in the subdvision)

You do this a lot in your posts. You start going off on what appear to
be tangents because you have not explained most of what is going on. So
you are going to wire all your doors (and windows so the system knows if
you have used a fire escape and call 911)? What else will this system
monitor that you haven't mentioned? I think this is going to be a
multi-thousand dollar system by the time it is done.

If you've watched my posts over the past year or so, I've discussed
other aspects of this "system".

If you haven't -- or haven't paid attention -- then there is nothing
*missing* from my original post that affects "PSTN Authentication".
Do I have to describe how I intend to use a particular capability
before it can be considered or designed? Haven't I clearly stated
my goal in describing an "automated attendant" and the parallels to
a "good secretary"?

If Bob calls answer the phone and tell him you are on the way yourself!

I'm not *at* the phone that Bob has called! Or, I *may* be yet don't
want to get drawn into a conversation with Bob which will delay
everything *else* I may have planned.

[Again, think: good secretary!]

You mean mind reader?

If the device has been TOLD to "give Bob the following message", how
is that reading minds?

A "good secretary" would know -- from empirical observation ("Sheesh!
Every time I get Bob on the phone, I've got to hear about his *kids*
for 20 minutes!") -- that calls from Bob shouldn't be passed through
when there is a schedule to be met.

E.g., if we receive calls while preparing a meal (or, ABOUT to do so),
we don't bother to answer -- because we are BUSY with something "time
sensitive" (the food will spoil or our stomachs will complain). The
caller can try back later... instead of us answering, engaging in
pleasantries for some number of minutes, then begging off so we can get
back to a meal that HOPEFULLY hasn't gone cold during the interruption.

If you are calling you know to press "abcd" before the machine prompts
you for "xy".

Too easy for someone to notice. I much prefer spending extra effort
"training" it to my voice and then engaging in an authentication dialog
(even the number of words required for me to command it to perform a
specific action increases the chance of it verifying *my* speech
characteristics)

Good luck. I think this will be some time showing up.

I have no goal of it EVER "showing up" -- for anyone OTHER than me! :>
Thankfully, I have the money, resources and skills to pull it off
without having to wait for a vendor to do a (poor) job of it --- with a
"limited imagination"!
 
On Sat, 13 Sep 2014 21:13:00 -0700, Don Y <this@isnotme.com> Gave us:

On 9/13/2014 1:55 PM, Jim Thompson wrote:
On Sat, 13 Sep 2014 11:57:59 -0700, Don Y<this@isnotme.com> wrote:

I'm looking for ideas on how to provide (reasonable) authentication
over the PSTN. CID is too readily spoofed (usually by the very folks
that you want to "avoid"!).

A simple scheme might be to use unique identifiers from a large, sparse
ID-space -- providing the ID (DTMF or voice) would provide an indication
of the user. This has the advantage of being tied to a USER and not
a line/device. It sucks because it requires users to remember a
specific ID (for *each* party that they intend to call!)

I'd settle for a reasonable-cost system that required the caller to
enter some 4-digit code such that robo-calls would be snuffed... I'm
tiring of the crap.

A true robot would be stymied by "Please press <digit> now".

A "telemarketer", OTOH, would not ("OK, I'll press that!").
(nowadays, it seems like a robot dials and hands off to a human
when the callee "answers")

If the <digit> was "canned" (i.e., the same for every/many instances of
this device), a robocaller could just blurt out the code unconditionally
to bypass that mechanism.

If it was a *single* changeable (or "random") digit, then pressing all
keys, sequentially, unconditionally, would eventually hit upon the
correct digit (i.e., you would have to allow perhaps *two* attempts
and REQUIRE no more than two before validating the input)

Any code that requires legitimate callers to remember it is an
inconvenience. If you could be assured a "timely" response by the
callee ("device"), I suspect you could program the code as a part
of the actual phone number -- just "delayed" (e.g., 555-1212%%%123456
where '%' forces an unconditional 1 second pause)

But, I want caller *identification*, not *just* "is this a human"...

Just make it a crime for the bastards to do and start prosecuting
white collar horseshit like we should have been doing for decades, but
haven't... Usually because too many political and government officials
were also involved.

It is like the goddamned gangs. The pigs keep adding numbers as they
claim there is a problem, but I do not see them cutting the head off the
snake. I see complacent assholes... Everywhere. Assholes who should
not get another additional fucking dime UNLESS AND UNTILL they SOLVE the
fucking problem.

One does NOT simply treat the symptoms and expect the entire infection
to be curtailed.

Fucking make it a crime and tell the bastards that they HAVE TO come
up with a NEW schema that does NOT involve a goddamned telephone!

And PROSECUTE the motherfuckers who ignore it, and if it is a major
company, SIEZE the motherfucker's assets.

SMITE THE BASTARDS ON THE FACE and they will run away!
 
On Sun, 14 Sep 2014 08:59:42 -0700, DecadentLinuxUserNumeroUno
<DLU1@DecadentLinuxUser.org> wrote:

On Sat, 13 Sep 2014 21:13:00 -0700, Don Y <this@isnotme.com> Gave us:

On 9/13/2014 1:55 PM, Jim Thompson wrote:
On Sat, 13 Sep 2014 11:57:59 -0700, Don Y<this@isnotme.com> wrote:

I'm looking for ideas on how to provide (reasonable) authentication
over the PSTN. CID is too readily spoofed (usually by the very folks
that you want to "avoid"!).

A simple scheme might be to use unique identifiers from a large, sparse
ID-space -- providing the ID (DTMF or voice) would provide an indication
of the user. This has the advantage of being tied to a USER and not
a line/device. It sucks because it requires users to remember a
specific ID (for *each* party that they intend to call!)

I'd settle for a reasonable-cost system that required the caller to
enter some 4-digit code such that robo-calls would be snuffed... I'm
tiring of the crap.

A true robot would be stymied by "Please press <digit> now".

A "telemarketer", OTOH, would not ("OK, I'll press that!").
(nowadays, it seems like a robot dials and hands off to a human
when the callee "answers")

If the <digit> was "canned" (i.e., the same for every/many instances of
this device), a robocaller could just blurt out the code unconditionally
to bypass that mechanism.

If it was a *single* changeable (or "random") digit, then pressing all
keys, sequentially, unconditionally, would eventually hit upon the
correct digit (i.e., you would have to allow perhaps *two* attempts
and REQUIRE no more than two before validating the input)

Any code that requires legitimate callers to remember it is an
inconvenience. If you could be assured a "timely" response by the
callee ("device"), I suspect you could program the code as a part
of the actual phone number -- just "delayed" (e.g., 555-1212%%%123456
where '%' forces an unconditional 1 second pause)

But, I want caller *identification*, not *just* "is this a human"...


Just make it a crime for the bastards to do and start prosecuting
white collar horseshit like we should have been doing for decades, but
haven't... Usually because too many political and government officials
were also involved.

It is like the goddamned gangs. The pigs keep adding numbers as they
claim there is a problem, but I do not see them cutting the head off the
snake. I see complacent assholes... Everywhere. Assholes who should
not get another additional fucking dime UNLESS AND UNTILL they SOLVE the
fucking problem.

One does NOT simply treat the symptoms and expect the entire infection
to be curtailed.

Fucking make it a crime and tell the bastards that they HAVE TO come
up with a NEW schema that does NOT involve a goddamned telephone!

And PROSECUTE the motherfuckers who ignore it, and if it is a major
company, SIEZE the motherfucker's assets.

SMITE THE BASTARDS ON THE FACE and they will run away!

As long as we have politicians whose only concern is re-election,
nothing will be done.

The do-not-call "law", as written, exempts politicians.

Perhaps a blacklist (which I already have via Ooma) plus a whitelist
of allowed callers, with all others going to voicemail?

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
On Sat, 13 Sep 2014 23:48:52 -0500, ChesterW <iamsnoozin@yahoo.com> Gave
us:

On 9/13/14, 1:57 PM, Don Y wrote:
Hi,

I'm looking for ideas on how to provide (reasonable) authentication
over the PSTN. CID is too readily spoofed (usually by the very folks
that you want to "avoid"!).

A simple scheme might be to use unique identifiers from a large, sparse
ID-space -- providing the ID (DTMF or voice) would provide an indication
of the user. This has the advantage of being tied to a USER and not
a line/device. It sucks because it requires users to remember a
specific ID (for *each* party that they intend to call!)

A more elaborate scheme could rely on voice-print identification.
Ideally, obtaining a voice print from the party at some "registration"
time. To address "playback" attacks, the caller could be required to
make a statement indicated at the time of the call.

Any sort of call-back scheme falls down because of the possibility
of theft of service that it presents. (It also assumes the user
would be at a fixed "location")

Then, there are a whole set of "class identification" schemes (i.e.,
where the type of caller is needed, not the actual identity -- robocall
prevention, etc.). I figure anything interactive will beat them
("Press <digit_determined_at_time_of_call> now", "How much is <digit1
plus <digit2>?" etc.)

My goal, here, is to provide an "automated attendant" function -- sort
of an "electronic secretary" that can screen calls intelligently:
- route all calls from political parties to /dev/null
- don't even let the phone *ring* if it's a telemarketer
- when I am asleep, take a message from any of these callers
- whenever <someone> calls, *find* me!
- if Bob calls, tell him I am on my way
- if *I* call, give me access to <whatever
etc.

Obviously, the cost (inconvenience?) to the caller can vary as the
"value" of the service he/she is expecting.

Thx,
--don
Hi Don,

Use a one-time-pad for challenge-response. Give each caller their own
pad. If it's generated using a good random source, and the responses are
not re-used, it will keep out even the NSA. That is, assuming they don't
steal your physical copy of the pad, or just make you give it to them
through coercion. I briefly considered doing something like this as a
commercial product, but then I realized all of my customers would be
drug dealers.

ChesterW

If you are not going to declare the behavior itself to be a crime,
then we need to modify the current system to REQUIRE FULL CALLER ID on
ALL calls, regardless of source, and make it 100% free to all hard line
POTS customers.

If the bastards feel they have a right to call me and waste my time, I
should have the right to ID the motherfuckers, and DISCHARGE their
dishonorable asses before my phone even rings a second time!

It is over-tolerant citizenry that lets these greedy bastards get this
way.

The goddamned phone companies charge too much, and for every little
thing... still.

The goddamned cable companies are part of this as well. Way too
fucking much for way too fucking little. They make hundreds of millions
a month and we are too fucking blind to see the disparity between their
money suck and their delivered goods. The fucking picture quality was
better back in the analog days compared to some of the compression
artifact ridden crap they spew now.

Americans just do not realize how badly ripped off we are being right
now. The water, the phone, the electric, the rent... all way too high,
and done by bastards that deserve far less.

That is America? No. That is Greedifornia gone wild.

It is gonna fuck us, people. And the pigs are not gonna be here to
protect us when it does.

Orwell was just off by a few decades.
 

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