tnixon@hayes.uucp (03/28/91)
I am studying the issue of increasing security and privacy of modem
communications at the physical layer, and would appreciate hearing
any comments or ideas you might have. I'm not looking for new
_inventions_ (please DON'T send me anything you consider to be
confidential or trade secret), but your opinions on the usefulness,
effectiveness, and value of commonly-used techniques such as
call-back security (within a modem; I, for example, think it is more
effective when controlled by an external device so that incoming and
outgoing calls are on different lines), encryption (built into the
modem, like data compression), modem-based passwords (with the
exchange of information handled by the error control protocol,
possibly using an encrypted challenge/response system), etc. I'm
also interested in your opinion on whether new techniques such
as modem-based decoding of caller-ID information would be useful.
There are currently no US or CCITT standards regarding these
functions (in modems), and your input will help me to decide whether
or not to initiate such activities. Thanks very much in advance for
your comments either email or posted to the group.
-- Toby
--
Toby Nixon, Principal Engineer | Voice +1-404-840-9200 Telex 151243420
Hayes Microcomputer Products Inc. | Fax +1-404-447-0178 CIS 70271,404
P.O. Box 105203 | UUCP uunet!hayes!tnixon AT&T !tnixon
Atlanta, Georgia 30348 USA | Internet hayes!tnixon@uunet.uu.netlairdb@crash.cts.com (Laird Broadfield) (03/29/91)
In <3888.27f10f22@hayes.uucp> tnixon@hayes.uucp writes: >I am studying the issue of increasing security and privacy of modem >communications at the physical layer, and would appreciate hearing >any comments or ideas you might have. I'm not looking for new >_inventions_ (please DON'T send me anything you consider to be >confidential or trade secret), but your opinions on the usefulness, >effectiveness, and value of commonly-used techniques such as >call-back security (within a modem; I, for example, think it is more >effective when controlled by an external device so that incoming and >outgoing calls are on different lines), encryption (built into the >modem, like data compression), modem-based passwords (with the >exchange of information handled by the error control protocol, >possibly using an encrypted challenge/response system), etc. I'm >also interested in your opinion on whether new techniques such >as modem-based decoding of caller-ID information would be useful. IMO: Callback security is a Good Thing, but given the current (low) level of communication between CPE and the CO, far too easy to defeat if it goes out on the same line. Therefore (as you point out) this one should be handled outside the modem. The rest of the techniques you mention, however, gain substantially by being built into the modem. The tamper-ability factor is reduced hugely by embedding all that stuff. Modem-based passwords and encryption would seem to go hand-in-hand, though, with both devices implementing an encryption scheme and refusing to talk unless they both have the same key(s). The value of a user giving a modem a password seems dubious. The one scenario I can see this being useful, is in a challenge-response scenario, with one of those little keypad/display gadgets (type in the challenge, give back the displayed response.) This might be useful if the callers are expected to be using a variety of equipment to call in. An intermediate step might be a dongle-type device that could be put inline with a non-secure modem that would allow modem commands through, but when awoken by the secure modem, it would get into the act. Physical "keys" are another approach, so are centrally distributed keys, so is the combination of both (e.g. the way an STU3 works.) The physical key business presents vendor-compatibility problems, but the central issuer business could be cross-standardized. (Didn't I see something here or in c.d.telecom a few months ago about the Bells providing a "registered call" service (never mind the MFJ, eh?)) Caller-ID reading would be useful for other reasons, as well as security, and should be implemented *ASAP* without waiting for a "security" confab. It's not that useful for serious security since it could be spoofed without much difficulty. $0.02! -- -- Laird P. Broadfield | Year after year, site after UUCP: {akgua, sdcsvax, nosc}!crash!lairdb | site, and I still can't think INET: lairdb@crash.cts.com | of a funny enough .sig.
dotytr@nscultrix1.network.com (Ted R. Doty) (03/29/91)
While it's all well and good to try to implement security in comms products, I suspect that it is an easy way to go out of business (did anyone notice when Tempest Technologies Inc. went into liquidation?). The *real* problem is that most customers don't think they need more security, and sure don't want to pay for it. Yes, there are a number of exceptions - customers who understand and support (with their $) effective security. But for each of these, there must be a thousand who don't. Remember the Internet worm? Is security really any better now than two years ago? From a practical point of view, do *you* want to have to manage the distribution of a million keys? 10000? I know I don't. Can you convince the vendors to do this? (answer: sure - if they can charge customers for the service ... see above). My suspicion is that security will remained confined to a few sites that really need it (U.S. Government), and that the rest of the world will some how get by. I'd like to be wrong about this. -------------------------------------------------------------------------- Ted Doty, Network Systems Corporation | phone: +1 301 596-2270 8965 Guilford Road, Suite 250 | fax: +1 301 381-3320 Columbia, MD, 21046 USA | voice mail: (800) 233-1485 -------------------------------------------------------------------------- These opinions are mine; if you want the opinions of Network Systems, why don't you ask them?
root@zswamp.fidonet.org (Geoffrey Welsh) (03/30/91)
>From: tnixon@hayes.uucp >[...] commonly-used techniques such as call-back security >(within a modem; I, for example, think it is more effective >when controlled by an external device so that incoming and >outgoing calls are on different lines), Given current technology (i.e. that it is possible to intercept outgoing calls on that same line and simulate an outbound connect), you're right... but this applies to big companies which can afford racks of modems and hunt groups. Let's not forget that I, typical of many manufacturers' end users, have only one modem and one line for it. Many of my fellow BBS operators have a callback validation system which is used only once, to verify the phone number given. Naturally, the database to be used (the user file) for duplicate number searching, prank filtering, and general logins (if callback security were to be enabled) would be beyond the capability of inexpensive modems... what would it add to the cost of a modem if it had to store 100 to 1,000 names & numbers, as well as be programmable to recognize the local police emergency, pizza order, and suicide crisis phone numbers? This should be left to the host system! The modem is a data link tool. Its job is to interface a computer to a set of phone lines, be they public switched or private leased. Manufacturers should concern themselves with the quality and features of that interface, not with assuming roles beyond it. For instance, it would be a great help to public access system operators if modems would be taught to recognize ANI and/or caller-ID; I'd *love* to see my Smartmodem 2400 announce proudly, "RING FROM 658-0311"! >encryption (built into the modem, like data compression), This is a less clear-cut issue; I suppose that there is a market for modems which could be programmed to scramble the data internally. I would suggest keeping this feature separate (an optional daughtercard?) for the more security-conscious customers. Then again, really security-conscious types would use scrambling in their in-house software over leased lines, wouldn't you think? <grin> >I'm also interested in your opinion on whether new techniques >such as modem-based decoding of caller-ID information would be >useful. I think I've already touched on that one; please do pursue this! >There are currently no US or CCITT standards regarding these >functions (in modems), Do you mean that there are standards suggesting how modems should convey this information to their hosts, or that the FSK codes for the caller's number have been standardized? I'd be surprised at the former, disappointed if the latter were not the case. What's Bellcore been up to for the past decade, aside of assigning south-central Ontario the area code that used to be for Mexico City?!? <grin> -- UUCP: watmath!xenitec!zswamp!root | 602-66 Mooregate Crescent Internet: root@zswamp.fidonet.org | Kitchener, Ontario FidoNet: SYSOP, 1:221/171 | N2M 5E6 CANADA Data: (519) 742-8939 | (519) 741-9553 The mile is traversed not by a single leap, but by a procession of coherent steps; those who insist on making the trip in a single element will be failing long after you and I have discovered new worlds. - me
ch@dce.ie (Charles Bryant) (04/04/91)
In article <3888.27f10f22@hayes.uucp> tnixon@hayes.uucp asks for: >... your opinions on the usefulness, >effectiveness, and value of commonly-used techniques such as >call-back security (within a modem; I, for example, think it is more >effective when controlled by an external device so that incoming and >outgoing calls are on different lines), In many places callback is useless (in the modem) since the called party cannot clear the call. This dosen't stop customers from asking for it though! Even after this is explained to them. >encryption (built into the >modem, like data compression), The sci.crypt folks will probably be more likely to be qualified to comment on this, but I think end-to-end encryption is better. Particularly if each end is at least as powerful as a PC. However, just as with error correction, I think it many poeple would be more likely to use it if it is in the modem merely because its there. Obviously if encryption is external to the modem, compression in the modem is not much use. I happen to think its crazy to use compression in the modem when neither end is a terminal since it just shifts the bottleneck from the phone line to the PC->modem link but that dosen't stop people from running ZMODEM over a compressed link insteqad of compressing the file first. The same is likely to happen if encryption is added to modems - but, most of the people who use modem-based compression wouldn't use any other compression otherwise so it would probably be the same for encryption and some is better than none. >modem-based passwords (with the >exchange of information handled by the error control protocol, >possibly using an encrypted challenge/response system), etc. Again, it is probably better to do this end-to-end (and easier unless one end is just a terminal) but its cheaper to implement since a noticeable delay in verifying a password is not a disadvantage. >I'm >also interested in your opinion on whether new techniques such >as modem-based decoding of caller-ID information would be useful. That would be useful for other reasons (e.g. callback, routing of calls) so its probably worth having. (But I can see problems too: e.g. usual modem line fails, so user connects modem to his fax line and wonders why his outgoing calls get put through to fax machine instead of the remote modem). -- Charles Bryant (ch@dce.ie) -- If you like the opinions expressed in this message, they may be available for rent - contact your local sales office. Low interest deals available.
smith@sctc.com (Rick Smith) (04/06/91)
I heard a rumor recently that some dialback modems are manufactured with a "backdoor" password that can't be disabled, which gives an outsider rather complete access to the modem. So check out your manufacturer closely. Evidently modem design/manufacturing skills are independent of good sense where security is concerned. I'm sorry I don't have more detailed information. If the rumor is true, the perpetrator certainly deserves to lose. Rick. smith@sctc.com Arden Hills, Minnesota
janm@dramba.neis.oz (Jan Mikkelsen) (04/06/91)
In article <3888.27f10f22@hayes.uucp> tnixon@hayes.uucp asks for: >... your opinions on the usefulness, >effectiveness, and value of commonly-used techniques such as >call-back security (within a modem; I, for example, think it is more >effective when controlled by an external device so that incoming and >outgoing calls are on different lines), encryption (built into the >modem, like data compression), modem-based passwords (with the >exchange of information handled by the error control protocol, >possibly using an encrypted challenge/response system), etc. What you need in a modem will depend on what you are trying to prevent. If you are trying to keep the entire dialouge on the line secret from someone tapping the line, then data encryption in the modem is useful. This is however not always the case. Commercial users are often more worried about authentication and confidentiality in other places. Cryptography in a modem does not help the data before it enters the sending modem, and after it leaves the receiving modem. It all comes down to a matter of trust. If the only place you mistrust with your data is the telephone line, then modem encryption is useful. Unfortunatly, many people mistrust more than that, and require encryption at a higher level - "end to end". There is also the problem of key management with a modem. They are harder to do, and it is unlikely that the modem will be able to asymmetric key cryptography (like RSA) at any reasonable speed. Modem based passwords and challenge/response could be useful but personally I would put all security functionality into the host where better control can be kept over the secure key storage, logging can be done, and there is greater control over the software. Now, a smart card reader, PIN pad and a modem in a tamperproofed case would be an interesting idea. I don't think anyone has attempted this yet, and it could certainly help with the key management problem. The cost of these things has come down significantly over the past few years also ... -- Jan Mikkelsen janm@dramba.neis.oz.AU or janm%dramba.neis.oz@metro.ucc.su.oz.au "She really is."
ronald@robobar.co.uk (Ronald S H Khoo) (04/07/91)
ch@dce.ie (Charles Bryant) writes: > I happen to think its crazy to use > compression in the modem when neither end is a terminal since it just > shifts the bottleneck from the phone line to the PC->modem link Well, if your iron can drive the modem at 38,400, and the modem's only [heh] a V.32, it's not _too_ bad :-) > but that > dosen't stop people from running ZMODEM over a compressed link insteqad > of compressing the file first. Convenience, of course. Actually, if they're using anything other than an *ancient* ZMODEM, ZMODEM itself can be asked to do the compression, which gets around the convenience problem, though I don't know how generally good its algorithm is. I've only ever used it for PostScript[TM] files, and it works OK for that. > If you like the opinions expressed in this message, they may be available > for rent - contact your local sales office. Low interest deals available. Ah yes, but does DCE get a cut ? :-) -- Ronald Khoo <ronald@robobar.co.uk> +44 81 991 1142 (O) +44 71 229 7741 (H)
zuck@mgsscsg.UUCP (Zuck Zuckerbrot) (04/10/91)
just to throw my $.02 in, we here at motorola use a security system between our modems and the systems. every user has a credit card sized device with an lcd display with a six digit number that changes randomly (?) once a minute. to use it one dials in, connects with a modem, enters a four digit PIN followed by the number currently in the window. once validated, it allows you to pass through to the hosts. it's made by security dynamics in boston and is called the "ace system" "Project teams detest weekly progress reporting because it so vividly manifests their lack of progress." - unknown -- -Zuck Zuckerbrot | UUCP ...mcdchg!amtfocus!mgsscsg!zuck - -Motorola Inc. | FONE (708)632-6228 - -1475 W. Shure Drive S356 | FAX (708)632-4421 - -Arlington Hts., IL 60004 | DISCLAIMER=standard;export DISCLAIMER -
whitcomb@aurs01.UUCP (Jonathan Whitcomb) (04/13/91)
In article <37@mgsscsg.UUCP> zuck@mgsscsg.UUCP (Zuck Zuckerbrot) writes:
-just to throw my $.02 in, we here at motorola use a security system
-between our modems and the systems. every user has a credit card sized
-device with an lcd display with a six digit number that changes randomly (?)
-once a minute. to use it one dials in, connects with a modem, enters
-a four digit PIN followed by the number currently in the window.
-once validated, it allows you to pass through to the hosts.
-
-it's made by security dynamics in boston and is called the "ace system"
Recently I was helping a friend (a modem and computer novice) learn to
use a telecommunications package and modem to log into the computer
where she works (Glaxo, in RTP, NC). They use the number
generating cards that Zuck mentioned. I am very curious how these
work. Do all of the cards display the same number at the same
time, or does the computer have a quick way to compute what number
will be on the specific caller's card (based on the PIN)? If either
of these schemes are valid, those cards have to be _very_ accurate.
Can anyone fill us in on how this works?
**********************************************************************
Jonathan Whitcomb UUCP: <whitcomb%aurgate@mcnc.org>
Alcatel Network Systems, Raleigh, NC Delphi: JBWHIT
cs352a41@cs.iastate.edu (Adam Goldberg) (04/13/91)
whitcomb@aurs01.UUCP (Jonathan Whitcomb) writes: >In article <37@mgsscsg.UUCP> zuck@mgsscsg.UUCP (Zuck Zuckerbrot) writes: >-just to throw my $.02 in, we here at motorola use a security system >-between our modems and the systems. every user has a credit card sized >-device with an lcd display with a six digit number that changes randomly (?) >-once a minute. to use it one dials in, connects with a modem, enters >-a four digit PIN followed by the number currently in the window. >-once validated, it allows you to pass through to the hosts. >- >-it's made by security dynamics in boston and is called the "ace system" >Recently I was helping a friend (a modem and computer novice) learn to >use a telecommunications package and modem to log into the computer >where she works (Glaxo, in RTP, NC). They use the number >generating cards that Zuck mentioned. I am very curious how these >work. Do all of the cards display the same number at the same >time, or does the computer have a quick way to compute what number >will be on the specific caller's card (based on the PIN)? If either >of these schemes are valid, those cards have to be _very_ accurate. >Can anyone fill us in on how this works? I once did some consulting work for a client whose friend used the above system. The client wanted me to find out whether it would make sense for him to use something like it. The client's answer was no, but in the mean time I talked to the guy who used the card--it seems that the number displayed is verifiable by the host computer (ie, not just random), and that only certain numbers are possible. It may be (I don't know) that each card has its own set of numbers, ie the host can tell not only if the number is valid, but if it is valid who is calling in. Seems like this system is for the very paranoid or very secure, depending on your point of view. -- +-----------------------------------------------------------------------------+ ! Adam Goldberg ! * ! "It's simple! Even a PASCAL ! ! cs352a41@cs.iastate.edu ! * ! programmer could do it!" ! +-----------------------------------------------------------------------------+
jah@mojo.ots.utexas.edu (Jeff Hayward) (04/15/91)
In article <59727@aurs01.UUCP> whitcomb@aurs01.UUCP (Jonathan Whitcomb) writes: >Recently I was helping a friend (a modem and computer novice) learn to >use a telecommunications package and modem to log into the computer >where she works (Glaxo, in RTP, NC). They use the number >generating cards that Zuck mentioned. I am very curious how these >work. Do all of the cards display the same number at the same >time, or does the computer have a quick way to compute what number >will be on the specific caller's card (based on the PIN)? If either >of these schemes are valid, those cards have to be _very_ accurate. > >Can anyone fill us in on how this works? All of these "smart tokens" work on a challenge-response principle, in which the host's challenge, possibly with a user PIN, is input to the token which yields a response by performing some cryptographic operation on the challenge using a key specific to the individual. The host computer has the means to determine what the proper response should be for the given challenge and individual. In the case of the Security Dynamics device, I believe they use a stable clock as an implicit challenge, so they can be used in place of a password without modifying host user/password mechanisms much. The main advantage of these devices is that the response generated is only valid for the given challenge, thus they are relatively free from playback-type attacks. -- Jeff Hayward The University of Texas System +1 512 471 2444 Office of Telecommunication Services jeff@nic.the.net
pineapp@netcom.COM (Daniel Curry) (04/17/91)
Speaky of security modems. I have several Ventel 9600 plus modems that have the security feature. Everyone is on a Sun's workstations. What I don't understand is how do you set-up the /etc/uucp/L.sys file to get through the "direct connect" password. This is what I have in the L.sys file who dfw Any,1 ACUHAYES 2400 415-555-1212 "" \d\r\r\r ssword: venpasswd ogin: Uany ssword: unixpasswd When I runn uucico -r1 -x7 -swho this is waht I get Using dialer type ACUHAYES dialing Hayes 0\015ACU write ok 3\015Line open failed, NO CARRIER dcr returned as -1o