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Here come the encryption apps

blog.cryptographyengineering.com

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Re: Here come the encryption apps

#21

Post by chrisballinger »

moxie wrote: post #5

I work on two of the apps Matthew reviews here (RedPhone and TextSecure). What I didn't expect when I started working on these types of projects is that the cryptography is the easy part. I'm really honored to hear that my code has the ability to make Matthew Green drool, but that ZRTP stack was a two or three day project three years ago, and hasn't changed much since. The bulk of the work over the intervening period…

Hey moxie, your write-up about how you built your switching network was fascinating. Thank you for continuing to be an inspiration.

p.s. you have a broken link to https://github.com/WhisperSystems/RedPhone/wiki/Signaling-Pr... in the writeup for the text "write our own".

Re: Here come the encryption apps

#22

Post by moxie »

tptacek wrote: post #10
moxie wrote: post #5

I work on two of the apps Matthew reviews here (RedPhone and TextSecure). What I didn't expect when I started working on these types of projects is that the cryptography is the easy part. I'm really honored to hear that my code has the ability to make Matthew Green drool, but that ZRTP stack was a two or three day project three years ago, and hasn't changed much since. The bulk of the work over the intervening period…

I don't understand why you'd concede security to your competition; it is a genuine distinction. Most security people I know, and all the crypto people I know would choose your designs over those of the other designers in this review, not because of the quality of your application but because you're clearly a capable designer. I worry about the message we send with this "the competition is insecure apps" stuff. Some o…

What I really want is for everyone to be using secure communication tools all the time. Not just because it'd obviously be great if everyone were communicating securely day to day, but because in extreme events, people tend to use the tools they already have and are familiar with.

For the London riots, that was BlackBerry Messenger. For the Egypt riots, that was Facebook and Twitter. Maybe the next explosive event will feature WhatsApp? So my sense is that for tools to be attractive in moments where security is suddenly of really clear value, they have to first be attractive in moments where security is less clearly of immediate value.

You're right that security is always a genuine distinction, but it's perhaps not the most valuable one to most people. I certainly believe that if you say "here's an app that you can install on your phone, and it will make everything more secure without you ever having to look at it again or even know it's there," then people will install that app. But that's not what we're saying right now. I'd love it if people used RedPhone all the time for every call they made, but I know that it's still not perfectly on par or better than a normal phone call, so I know that people will have a hard time putting up with its usability deficiencies if they haven't seen or felt the direct consequences of the NSA warrentless wiretapping program (or whatever) yet.

This isn't to say that there aren't plenty of people who find it valuable for their work right now, just that I'd like for us to be setting our sights on the common case and delivering a product that exceeds peoples current expectations.

I think we're finally getting to the point with TextSecure where the normal day to day experience is as good or better than the stock Android SMS application, but we should really be chasing WhatsApp or Snapchat or whatever.

And totally, good cryptography is extremely important, and I think we should continue to be rigorous there, but I'm not entirely sure how to approach that with people that aren't actually interested in building secure products. Right now if you search "secure sms" in the Android Play Store, the first result is not TextSecure, but 100 results for apps with names like "extreme SMS locker pro!" that "hide" your SMS messages by doing hand-wavey things. We might ignore them, but other people aren't -- they have hundreds of thousands of installs. I have no idea what to do about that.

Re: Here come the encryption apps

#23

Post by moxie »

chrisballinger wrote: post #21
moxie wrote: post #5

I work on two of the apps Matthew reviews here (RedPhone and TextSecure). What I didn't expect when I started working on these types of projects is that the cryptography is the easy part. I'm really honored to hear that my code has the ability to make Matthew Green drool, but that ZRTP stack was a two or three day project three years ago, and hasn't changed much since. The bulk of the work over the intervening period…

Hey moxie, your write-up about how you built your switching network was fascinating. Thank you for continuing to be an inspiration. p.s. you have a broken link to https://github.com/WhisperSystems/RedPhone/wiki/Signaling-Pr... in the writeup for the text "write our own".

Thanks! (And thanks for the heads up on the broken link)

Re: Here come the encryption apps

#24

Post by loeg »

moxie wrote: post #5

I work on two of the apps Matthew reviews here (RedPhone and TextSecure). What I didn't expect when I started working on these types of projects is that the cryptography is the easy part. I'm really honored to hear that my code has the ability to make Matthew Green drool, but that ZRTP stack was a two or three day project three years ago, and hasn't changed much since. The bulk of the work over the intervening period…

moxie, I'm curious how the "short authentication string" prevents MITM attacks — can you shed some light on this or point me to existing documentation? Thanks!

Re: Here come the encryption apps

#25

Post by e3pi »

A `crypto app' I would like to have and see everyone use is to do the `...... beep .....' every 10 seconds.

Until a transparently layered Redphone, etc., secure and universally used protocol, this app assumes this and every connection is being recorded.

beep ...... beep ...... beep ......

Re: Here come the encryption apps

#26

Post by ams6110 »

loeg wrote: post #24
moxie wrote: post #5

I work on two of the apps Matthew reviews here (RedPhone and TextSecure). What I didn't expect when I started working on these types of projects is that the cryptography is the easy part. I'm really honored to hear that my code has the ability to make Matthew Green drool, but that ZRTP stack was a two or three day project three years ago, and hasn't changed much since. The bulk of the work over the intervening period…

moxie, I'm curious how the "short authentication string" prevents MITM attacks — can you shed some light on this or point me to existing documentation? Thanks!

It's some sort of key fingerprint. You know the key you sent to the other party, and the other party can compute the fingerprint of the key they received from "you." If they don't match, someone changed keys in transit.

Re: Here come the encryption apps

#27

Post by loeg »

tptacek wrote: post #19
rorrr wrote: post #17

Earlier quoted context omitted.

> I don't understand how Matthew can write a comparative review of encrypted chat clients and include one for which he has no technical information, not even a binary Well that's the point. If there's no source, don't trust that crypto app.

But that's not what he wrote. Read that part of the review again.

""" Overall code quality: Who knows

Should I use this to fight my oppressive regime? Yes -- if your fight consists of sending dirty self-portraits to your fellow comrades-at-arms. Otherwise, probably not. """

Am I missing something?

Re: Here come the encryption apps

#28

Post by loeg »

ams6110 wrote: post #26
loeg wrote: post #24

Earlier quoted context omitted.

moxie, I'm curious how the "short authentication string" prevents MITM attacks — can you shed some light on this or point me to existing documentation? Thanks!

It's some sort of key fingerprint. You know the key you sent to the other party, and the other party can compute the fingerprint of the key they received from "you." If they don't match, someone changed keys in transit.

Does this assume that the voice channel can't be doctored? But couldn't a MITM attacker do just that — compute the "correct" fingerprint and speak it to the recipient?

Re: Here come the encryption apps

#30

Post by randomchars »

venomsnake wrote: post #13

I don't think you can have security on a device you don't have root access. And since most of the phones are locked and untrusted does it matter how much exactly? And almost all really nasty regimes have already somewhat liberal view of using thermorectal cryptoanalysis anyway. Tor style obfuscation and retransmission with very low SNR masked as a torrent client could be a better way to go. If your government know th…

Root is not enough either. Most drivers are closed source (on phones) so you have no idea what the device is actually doing.
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