PGP Creator's Zfone Encrypts VoIP

Philip Zimmermann, creator of PGP wrote in to tell me about Zfone, his new system for encrypting any SIP VoIP voice stream. His first release is Mac & Linux only. I tested it with him using Gizmo as our client and it was pretty trivial to use. While it should work on most any SIP compatible VoIP client, he hopes that clients like OpenWengo and Gizmo will incorporate Zfone directly into the UI. Zfone has no centralization, and has been submitted to the IETF. He hasn't yet determined a license, but he believes strongly in releasing source code for all encryption products. A windows client is forthcoming.

Comments

typo

[Yahweh Doesn't Exist]

>His first release is Mac & Linux only.

you misspelled Windows.

oh... that makes a refreshing change.

My only concern

[QuaintRealist]

...is that the US (yes, I live there) will use security fears relating to terrorism to ban or severely restrict this technology. Some elements of our government seem almost Luddite (http://en.wikipedia.org/wiki/Luddite) these days.

Sad, because this kind of encryption would permit greater use of this technology in medicine under HIPPA privacy regulations.

Re:My only concern

[grub]

Entirely off topic, but it'd be nice if /. supported linking to wikipedia entries with a simple tag, ie.: if you could have used [[Luddite]] in your post much like how it works on wikipedia.

If you use that idea, Taco, I want a piece of the action!

Re:My only concern

[Aspirator]

I presume that this will be released outside the US, and allowed to migrate in.

Even then I'm sure that there will be attempts by the US Government to
prevent its use.

This is a significant advance in the search for privacy.

Re:My only concern

[Anonymous Coward]

I'd say it's dissapointing that the post had to link to a definition of Luddite in the first place.

Re:My only concern

[lucm]

Many country have much more severe regulations against encryption technologies than the USA. Just a few years ago there was an incredibly severe law in France, stating that even domestic encryption was under the government control.

Believe it or not, you actually live in a (somehow) free country.

Important Stuff

[WebHostingGuy]

This is important stuff as more and more phone traffic is routing open in the internet. While most people do not believe their emails are totally private, when it comes to talking on the phone I believe there is a perception (and assumption) that no one else is listening. SIP, Asterisk and all the flavors of VOIP is changing telecom and encryption is necessary.

Phil and Jon

[MDMurphy]

For some reason I got to thinking about Phill Zimmerman and DVD John [Johansen]. Both seem to pop up now and then and give us all reasons to smile.

Hmm... I wonder if Phil could come up with security that Jon couldn't find a way around?

Re:Phil and Jon

[merreborn]

I'm sorry, did I miss the story about DVD John breaking the public key encryption model? And blowfish? And the cypher du-jour?

He's released cracks for various pieces of software, but it's not like the guy's actually broken actual strong encryption algos.

http://en.wikipedia.org/wiki/Jon_Johansen#Other_pr ojects

Re:Phil and Jon

[Jah-Wren Ryel]

He's released cracks for various pieces of software, but it's not like the guy's actually broken actual strong encryption algos.

And such 'cracks' are the best way to attack otherwise strong crypto-systems - don't try to crack an algorithm -- crack the implementation. Look for the vulnerabilities in the systems that use strong cryptography and find the back-doors, or break in a hole in the wall, but trying to go mano-a-mano with the entire crypto community isn't a smart thing and you are exactly right -- that isn't what DVD-Jon has ever done.

Not that I would imply that CSS is a strong algorithm, it ain't. But the new stuff for BLU-HD-RAY uses AES and the stuff that the Zim-man is using to security VOIP also uses tried and true crypto algorithms. That doesn't mean there won't be flaws in the implementations that can be exploited and Jon-Jon He's Our Man, If He Can't Exploit It, No One Can!!! Yeah Jon. Or something like that.

It would also..

[TheAxeMaster]

It would also almost totally negate any ISP's attempt at shaping VOIP traffic to try and get people to buy their service instead. This has been somewhat of a question in recent months, but if you can encrypt your stream, then there's not much chance they can slow your packets. I'm all for the increased security as well. Now if we can only get them to cut down on the spam....

Re:It would also..

[ozmanjusri]

Hence we are back to stenography.

Is that shorthand for steganography?

Re:It would also..

[ozmanjusri]

He's gotta write those bytes down onto something!

Not really, - no coconut = 0, with coconut = 1.

(I suppose the VoIP equivalent would be TCP/IP over parrot?)

Good thinking. I wonder how many parrots each pigeon could carry.

Releasing the source

[romka1]

If he releases the sources won't companies like Vonage that are being subjected to voip packet throttling from copetitive ISPs just take it and use this technology for free?

Re:Releasing the source

[HolyCrapSCOsux]

Wouldn't that kinda be the point?

What ever happened to PGP Phone?

[WarlockD]

The MIT Website has taken it down, but I remember it working somewhat well between two IP address.

Was it just too far ahead of its time?

Re:What ever happened to PGP Phone?

[Winged]

PGPFone was a wonderful idea. The protocol it used was messy as all hell. I talked with Phil about it in 1997; he said that it wasn't being maintained because it didn't lend itself to being extended to actually use participants' PGP keys (instead of just "I hear this voice" authentication), and that at that point all rights to it were owned by the company that had just purchased PGP Corporation.

Re:What ever happened to PGP Phone?

[Antique Geekmeister]

As I remember, when it came out, there were patent issues with RSA in the PGP encryption. RSA owned the patents on RSA encryption used by PGP, but refused to release them for other uses, even if you phoned them up and tried to pay them for its use in another open source project. (I know: I tried.) RSA seemed more concerned aobut its inclusion in exported software than in actually making the software available. There were real USA export regulations about it, classifying encryption as a war material. Those regulations were found unconstitutional, and transferred from Customs to Commerce instead of thrown out, and we're still seeing them in the courts occasionally. It's why US users had such trouble using SSL keys as long as 128 bits on so many web browsers for such a long time.

So PGPphone had a serious legal battle to reach wide use, and it never caught on as well as not having a great user interface. I hope Phil's newer tool catches on.

No PKI?

[fossa]

Would it be useful to have the option, for those of us who have friends' PGP keys, to do the Zfone key handshake via PGP encryption that rather than verifying something by voice? It's fantastic from a "getting people to use it" perspective that it does not rely on PKI, but those who have already taken the plunge shouldn't be punished :)

Why not encrypt by default

[Matt Perry]

This article has me wondering about something. Why aren't we encrypting things by default? Why isn't encryption being built into the protocol when it's designed? It always seems that it gets tacked on afterwards, if at all, and we're worse off in the long run for it. Take VNC for example. If you want that encrypted you're told to send it over SSH. Wouldn't it be great if VNC traffic was encryped by design right from the start? The same applies to any other traffic (VoIP, IM, whatever). What happens is that many people don't encrypt because of the difficultly or they don't know any better. Unencrypted traffic is sent putting them at risk.

We know the network is hostile and retrofitting encryption onto something after the fact doesn't always work either because too many people using the unencrypted protocol, it's too hard to configure (as opposed to being mostly automatic like ssh connections), or just general security ignorance. What's really holding us back?

Re:Why not encrypt by default

[Savage-Rabbit]

This article has me wondering about something. Why aren't we encrypting things by default? Why isn't encryption being built into the protocol when it's designed? It always seems that it gets tacked on afterwards, if at all, and we're worse off in the long run for it. Take VNC for example. If you want that encrypted you're told to send it over SSH. Wouldn't it be great if VNC traffic was encryped by design right from the start? The same applies to any other traffic (VoIP, IM, whatever). What happens is that many people don't encrypt because of the difficultly or they don't know any better. Unencrypted traffic is sent putting them at risk.

There are lots of reasons why encryption isn't being widely used. For one thing there is the normal tinfoil hat reason, ie. that the people in charge don't want it becausy they wouldn't be able to stick their nose where it don't belong so they try to prevent such technology from being widely used. Alot has also to do with cost and computing overhead. Encrypting can be an expensive thing to do in terms of computing power and especially so if everything form all the network communications protocols to storage media content is bening encrypted. Doning encryption with special hardware is one solution but that adds cost and also the problem of the hardware algorithms becoming obsolete like WEP for example. Just try to get ahold of, say a 100mb photoshop file. Now copy it into the user home directory of a regular user on an OS.X machine, then do the same for antoher user using 'File Vault'. You will quickly discover that the latter operation takes alot longer since those 100mb's of Photoshop file are being encrypted. You should notice similar problems when comparing normal unencrypted file transfers over a network with transfers over a high strength encrypted link. VPN for example works noticably slower using port forwarding over an SSH tunnel.

Re:Why not encrypt by default

[Noksagt]

• Technological
  
  • Encryption implementation isn't free.
    
  • Encryption maintenance isn't free.
    
  • Unencrypted traffic is easier to sniff (which may be legitimately important).
    
  • Encrypyed traffic has a higher CPU overhead (which isn't always made up for).
    
  • Some people prefer to have one really good encryption program (SSH or a VPN) to route all traffic over.
    
  
  
• Legal
  
  • Encryption can't always be exported from every country to every other country.
    
  • Sometimes it may be illegal to encrypt traffic.
    
  
  

Re:Why not encrypt by default

[chefmonkey]

Why isn't encryption being built into the protocol when it's designed?

For any IETF protocol developed in the past 10 years or so, it is. For example, RFC 3261 (which defines SIP) makes TLS encryption *mandatory* to implement. It does allow the users/administrators/whatever to turn it on and off, but you can't say your implementation is RFC 3261 compliant unless it contains TLS encryption.

For most other important protocols defined before the IESG required strong security in all protocols, there have been significant efforts to revise them as necessary to provide encryption. For example, RFC 3711 defines a mechanism for encrypting RTP (the voice packets in a VoIP call).

Anyone who bothers to actually implement to spec already has released products that do encryption, many by default. For example if I use the Snom 360 SIP phone on my desk to call anyone else using a client that has actually implemented all of RFC 3261 (instead of whatever small portion of it amused them) and implemented RFC 3711, both the signaling and the media will be strongly encrypted BY DEFAULT. And that's the way it was configured when I took it out of the box.

The fact that some current implementations don't bother following spec impugns their designers and implementors, not the protocols they're using. Using the standardized VoIP protocols available today, everyone *should* be able to make encrypted calls.

Re:Why not encrypt by default

[Matt Perry]

I think you've answered your own question. Unix mantra: do one thing and do it well. SSH is the encrypted transport layer. No other communication layer needs encryption.

So we should manually establish an SSH connection from our mail server to every MTA that we are communicating with? We should also establish a manual SSH connection for IM connections to every IM server that we connect with? SSH isn't a panacea.

great

[Anonymous Coward]

great idea, this is very much needed. I don't know how secure this actually is, the writer (phillip zimmermann) said he builds the encryption into tcpstack of whatever operating system the user is running and the key exchange is done automatically between hosts.. he also makes the statement that this technology/standard (zfone) would be integrated into the end-user software, in the near future. I'm not sure why he's so confident, it's nice but who's to guarantee any sip softphone end-points or better yet, hard telephones, will actually have this built in.

hmm.. i wonder if I have linux nat router running this (and it being my default gateway, if it will automatically encrypt any sip sessions if the end system is running the zphone gui. I mean this apparently works at the network layer (like tcpdump, promiscuously), I wonder if it has to be running on the same system the sip session is originating from. oh dear, i really need to replace my dlink router these days.

Re:Does it matter???

[Aspirator]

You're right. I have now downloaded the source, from within the US.
There are prohibitions on export in the (many) terms to which you have to agree.

How long before it's all over the world?

Encryption is hard

[user9918277462]

Because encryption is very difficult to do correctly. And we should all know by now that a false sense of security is worse than no security at all.

There's also the not insignificant fact that encryption is complex to use and administer. Adding in robust encryption is not free from a user-friendliness perspective. Much thought has to be put into reducing the user-visible complexity as much as possible so that the user base will actually use the encryption, and use it in such a way that security is preserved. Not trivial.

Re:Encryption is hard

[Bogtha]

Wanna encrypt VNC?

ssh -L 5900:localhost:5900 somehost.org
vnc to localhost:5900

Was that hard? No.

That's because you skipped the hardest step - the out-of-band communication necessary to establish key authenticity. The first time you connect to a host via ssh, it displays a fingerprint and asks you if it should be trusted. Most people don't value encryption enough to even bother installing the relevant software, what makes you think that they value encryption enough to figure out a way of validating the fingerprint securely?

Re:Encryption is hard

[kwerle]

That's because you skipped the hardest step - the out-of-band communication necessary to establish key authenticity. The first time you connect to a host via ssh, it displays a fingerprint and asks you if it should be trusted. Most people don't value encryption enough to even bother installing the relevant software, what makes you think that they value encryption enough to figure out a way of validating the fingerprint securely?

At the risk of summoning the ire of cryptographers everywhere:
So what.

Skip the whole fingerprint validity thing - I do all the time. I never call the sysadmins of machines I'm using to make sure their self-signed certs are really them (mail, https, ssh, whatever). It has bit me 0 times. As far as I'm concerned, that answer is just an excuse to dismiss a trivially simple 90% solution. As a matter of fact, my system uses secure SMTP (what's the right acronym?) in it's MTA. Nobody validates SMTP's keys for sending - they just trust the message is going to the right machine and sends it encrypted. Folley! But it works fine.

But partial security is worse than no security!

BS. There is no total security. Someone can always root that machine and get your password.

In the meantime we have VNC in the clear, because "encryption is hard to do".

Total security is virtually impossible. Encryption is pretty easy, and we'd all be better off using more of it.

Checksums, distro needs sigged.

[Anonymous Coward]

As there is no cryptographic signature on the package, these are my sums
as received. Please compare and post if yours are different.

SHA1 (zfone-linux.tar.gz) = aa9ac66a5dce43cff2639787f30e939078b47ebe
MD5 (zfone-linux.tar.gz) = c6a47feca0fd5cb5bf72a8f6a1e8f207

PRZ, please sign your packages! Thanks, World.

SRTP?

[Gerald]

What's the difference between this and SRTP?

I agree, it is hugely important

[maillemaker]

Hopefully, this will be the straw that breaks the camel's back.

Ultimately, ALL traffic should be encrypted, whether it is VOIP, email, web browsing, whatever.

The guy is right when on his home page he talks about how it is so difficult to implement this sort of stuff as an add-on for emails, managing keys and the like. It's why no one does it. Of course, there has always been a computing overhead, also, which is why only pages that "need" to be secured currently are. But as horsepower goes up, those limitations should go away.

Ultimately, it should be a matter of course before all traffic that goes in our out of your computer is encrypted by default.

Hopefully this is the start of something huge!

Steve

Re:I agree, it is hugely important

[utlemming]

I tend to agree that with CPU's increasing in speed and power, that the cost of encyrpting goes down. But also the cost of breaking the same codes goes down. Right now it takes 2^120 rounds to break AES encrpytion while trying to brute force. So in order for the higher speeds of the CPU argument to hold to encrypt everything, encryption technology will have to go up. Right now 128 bit is acceptable, but as speeds increase, then the encrpytion will have to be changed as well. And that will require faster processors.

Re:I agree, it is hugely important

[stephentyrone]

yes, but the nice thing is that for most encryption methods, the work to do the encryption grows linearly (at worst polynomially), whereas the work to break the encryption grows exponentially in key size. the larger the key gets, the bigger the gap between work to encode and work to decode.

Re:I agree, it is hugely important

[Myria]

Almost all commercial multiplayer games use encryption as security-through-obscurity, usually by using custom algorithms. In online games, you're trying to keep cheaters from manipulating packets, not keep eavesdroppers from watching.

For https and such, setting up the connection is the majority of the work. Public-key key exchange (public-key certificates, Diffie-Hellman, etc.) is an expensive operation because it requires a modular exponentiation on the part of the server. However, once the connection is set up, the cost of encrypting each packet is extremely small.

Melissa

Re:I agree, it is hugely important

[iabervon]

Encrypting everything doesn't help security at all. It only helps if you have some idea of who the intended recipient is. For most traffic, that's an application-specific concern, and so a general encryption mechanism is useless. For example, if I want to send email to a gmail user, and I care about it being private, I have to find a private key for the user. It doesn't help to just encrypt (great, nobody at all can read it), or encrypt it for secure transit to Google (why should I trust Google more than other random intermediaries?). I need the actual user's PGP key, and that requires an application specific identity specification (i.e., the email address), with a user-specific way of determining that I've got the right address for the communication.

PGPfone, Speak Freely

[Noksagt]

I can remember Phil's PGPfone which was released before VoIP was "the next big thing." It used GSM speech compression and 3-DES/CAST/Blowfish cryptography "to give you the ability to have a 'real-time' secure telephone conversation" (directly over 14.4 Kbps (or faster) modem-to-modem, through the Internet, or through AppleTalk).

That died. It is good to see a new alternative that has adopted newer standards.

Another "oldy but goody" was Speak Freely.

Related project

[Anonymous Coward]

There was a presentation from another group (wasn't Phil, although he was there) at DefCon 13 relating to reverse-engineering the GSM voice compression so that data could be fed through a GSM voice link accoustically with almost no overhead (in other words, at close to the GSM native digital bandwidth). The intent being to provide a means to attach accoustic peripherals (handsfree headset for example) that could perform encryption and send the encrypted, digitized voice over the GSM link accoustically (to be recieved and decoded by a similar device on the other end), thus allowing encrypted voice communication over an untrusted and unmodified cell phone without the need to install any software.

Re:Related project

[twiddlingbits]

From your description they just re-invented the Modem using Digital instead of Analog and with encryption. This isn't new, the STU-XX secure phones used by the Government for Classified voice calls work very much the same way. Might be some IP infringement issues with thier work as well.

Who needs encryption?

[Shanesan]

Igpay atinlay isway ethay estbay ayway otay encryptway ouryay onversationcay!

Ob. Simpsons Ref

[magefile]

Could Phil microwave a burrito so hot even Jon couldn't eat it?

Well...

[Anonymous Coward]

SIP is just a protocol that sets up connectivity and media control; the stream itself is not covered by the SIP protocol. For that, you need something that supports Secure RTP (SRTP), which encrypts the payloads of all RTP streams. If you've managed to encrypt SIP, all you're doing is encrypting call setup and feature requests. Your conversation is not encrypted.

In other news...

[gizmonic]

Philip Zimmermann has apparently vanished from the face of the earth. Film at 11.

Re:PGPfone: Full duplex mode did suck

[Noksagt]

try as I might, with a friend at the other end of a 28.8 connection and also locally in my home between two PC's with 100Mbit/s connections, I could not get anything better than short bursts of audio to either end...Did you have any luck with PGPfone?

I seem to recall that full duplex sucked in this way on 56.6. I think I half duplex (push-to-talk) was passable. But it was also so inconvenient, so I opted to not secure voice traffic. I thought I tried it on broadband with a bit more luck. It didn't seem to suck significantly more than any other VoIP at the time. I do think that the Macintosh version was slightly more reliable (it was originally released on the Mac & eventually ported to win32). (And, again, it didn't suck THAT much more than any other Mac Class app.)

I think I tried it with the V1 series however.

v1+win32 might have been part of the problem. I don't recall the differences between v1 and v2, but NAI seems to have killed much of the goodness in any of the apps they acquired, so I wouldn't exactly hold my breath.

I hope a Zfone proxy is made so that hardware ATA's can be secured?

Indeed. And that hardware SIP devices start adopting it (some should be able to adopt it via firmware, not that the hardware manufacturers will actually DO that).

Why not use OpenSSL?

[Cthefuture]

I know the API isn't the greatest and the documentation completely sucks but someone with OpenSSL knowledge could put together a SIP-friendly API in a couple hours.

At least then you're using a public, well hammered on API and would have a multitude of algorithms to choose from. I mean OpenSSL is used in tons of stuff and gets lots of field testing.

I have never understood the point of PGP with its proprietary crap formats when there are open, standardized formats for the stuff it is typically used for (S/MIME, X509, PKCS#12, etc.) and that are supported in standard applications rather than require some goofy PGP add-on.

Re:Why not use OpenSSL?

[rodac]

VoIP is different from most other traffic types in that it is hard realtime and needs real low latency. This means VoIP uses UDP

OpenSSL builds encrypted sessions over TCP. TCP is not designed to work well for the requirement space needed by VoIP.
If fact, it just would not work well at all.

Re:Why not use OpenSSL?

[Cthefuture]

OpenSSL is not just an SSL API. It's a full cryptographic API. The socket stuff is not even in the core crypto library. There is libssl and then there is libcrypto. Both are part of OpenSSL.

OpenSSL is a misnomer.

I didn't mean "use SSL", I meant use OpenSSL the cryptographic library that supports all that standard stream ciphers. You can use whatever networking stuff you want outside of OpenSSL.

Re:traffic shaping reality check

[wolrahnaes]

The mention of 911 gives me an idea for an interesting angle to ensure ISPs can't neuter VoIP.....claim that by doing so they're endangering lives in the event of a 911 call.

Encryption

[Mark_MF-WN]

Let's be honest -- this guy needs to go to jail NOW. Privacy is almost as treasonous as sharing or questioning your leaders.

Re:Encryption

[advocate_one]

Privacy is almost as treasonous as sharing or questioning your leaders.

no, sorry, you can keep Bush... do not share him...

My security fears

[webweave]

I don't live in the US but I live very close and almost all of my IP traffic travels through the US at some point and my worry is that any business information collected by the US/CIA/FBI or other US agency would be made available to US companies. There have been court cases in the past of US sponsored spying benefiting US companies. They say they are after terrorist but who knows? With the knowledge of past activities of US spies and the current computing power of the US agencies all foreign businesses would be well advised to encrypt all sensitive information.

http://www.motherjones.com/news/feature/1994/05/dr eyfuss.html

http://web.nps.navy.mil/~relooney/4141_Spring2002. pdf

http://www.commondreams.org/headlines/070200-02.ht m

Not using encryption is to believe GWB when he says "Trust me"

What is the big deal?

[Guspaz]

Why do some people jump all over protocol-specific encryption as helping terrorists, or other such nonsense?

There is a great deal of concern over Skype being encrypted. People say it can be used by terrorists for encrypted communication. The thing is, throw up a VoIP server of some kind (Even the free ones like Ventrilo or TeamSpeak), and connect to it using something like Hamachi. Bam! All your UDP voice traffic is encrypted.

Heck, you can even do it with TCP. SSH tunnels encrypting two-way Shoutcast streams. Huzzah! Encrypted two-way voice communication! Heck, pump the shoutcast stream over HTTPS and that'd be encrypted too.

So, this is why I don't get it. Why complain about Skype when there will always be ways to encrypt voice traffic over the internet? Programs like Hamachi (Encrypted P2P VPN solution with an IM-like interface) make it insanely easy to set up more secure solutions than Skype, and there is always SSH tunnels as a fallback.

So how does this relate to the current situation? Well, people are sure to complain that this new program somehow helps terrorists. So I'm just saying that that is BS.

QoS

[Nonillion]

Hmmmmm, could one use this method to get around some of these pesky Quality Of Service restrictions? Because we all know the carriers like to enforce these things to keep you from getting quality from your VoIP service.

I've got an easy answer...

[ImaLamer]

Because it isn't always needed.

VNC? What if I'm only using it over a Cat-5 cable on a private network? Who am I encrypting it from?

You've always got FreeNet. But you aren't using it are you?

Is Phil marrried?

[Lord Kano]

I have a 22 year old sister that I'd like to introduce him to.

I NEED a guy like this in the family.

LK

Re:User friendly encryption..

[user9918277462]

I can do a Diffie-Hellman key exchange which adds zero complexity to the user experience: no key management hassles at all.

You're proposing using a system with known design vulnerabilities. See my comment above re: false security vs no security at all.

As soon as you add key management into the mix (which is absolutely crucial and, due to the strength of modern ciphers, becomes the keystone of security) things get very complicated very quickly (as you allude to wrt SSH).

That is not to say that it is an insurmountable problem: an example is web browser SSL. The mechanics of key authentication and distribution are actually quite complex, however this is hidden almost entirely from the user. This is done through a large and relatively robust crypto infrastructure which was created because commerce makes SSL necessary. The public's right to privacy does have the same corporate backing.