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Viber adds end-to-end encryption

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Re: Viber adds end-to-end encryption

#51

Post by CiPHPerCoder »

CaptSpify wrote: post #46
ryanlol wrote: post #32

Earlier quoted context omitted.

That's fair! But you need far more than just the crypto code to create a client, I think open source protocol specs would already achieve this. And my main complaint was with the claim that open sourcing their crypto code would somehow make a meaningful difference to the security of these applications to the extent where you could consider all applications that haven't done so "insecure".

I don't think I get your complaint Without open-sourcing the crypto, they could be just doing rot16($message) for all we know. Open-source is a requirement for being considered secure. It doesn't mean they aren't secure if they aren't open-source, but that you shouldn't consider it so, because you don't know if it is or not.

> I don't think I get your complaint

> Without open-sourcing the crypto, they could be just doing rot16($message) for all we know.

There are two things you can do:

1. Watch the outbound traffic and attempt known-plaintext attacks

2. Reverse engineer the app

Neither is particularly difficult. Most Android apps are trivial to break apart using Lobotomy. A large swath of software security folks specialize in binary auditing.

Re: Viber adds end-to-end encryption

#52

Post by CiPHPerCoder »

goodplay wrote: post #47
exo762 wrote: post #26

Earlier quoted context omitted.

Does bad crypto counts? I don't think so.

I keep seeing this accusation get flung around whenever someone mentions telegram but never proof. I remember telegram had a vulnerability once and then it was patched just like any other security software. You shouldn't throw around accusations without proof.

Here's your proof: http://cs.au.dk/~jakjak/master-thesis.pdf

See also:

http://www.cryptofails.com/post/70546720222/telegrams-crypta...

https://moxie.org/blog/telegram-crypto-challenge/

Re: Viber adds end-to-end encryption

#53

Post by goodplay »

onli wrote: post #49
goodplay wrote: post #45

Earlier quoted context omitted.

Come on, it would definitely still be possible with AGPL code. What brought people to whatsapp is its ubiquity and the fact that it just works, and what keeps them from going elsewhere is the inevitable network effect. Nothing in the AGPL prevents either from occurring.

I think you are misunderstanding jeena. If ejabberd were AGPL, then a fork/a instance of it like Whatsapp would be legally obliged to open up their code as well. No idea whether the assumption is true that Whatsapp is just a branded deployment.

I still don't understand how opening up the codebase would prevent them from being successful.

As the countless messaging apps out there demonstrate, the value of communication apps lies in the network they build. If they provide a decent UX, and successfully bootstrap a network large enough, it wont matter if their code is open.

Re: Viber adds end-to-end encryption

#54

Post by goodplay »

CiPHPerCoder wrote: post #52
goodplay wrote: post #47

Earlier quoted context omitted.

I keep seeing this accusation get flung around whenever someone mentions telegram but never proof. I remember telegram had a vulnerability once and then it was patched just like any other security software. You shouldn't throw around accusations without proof.

Here's your proof: http://cs.au.dk/~jakjak/master-thesis.pdf See also: http://www.cryptofails.com/post/70546720222/telegrams-crypta... https://moxie.org/blog/telegram-crypto-challenge/

Is it cryptographicly broken or not? Can I read the plain text of the traffic I capture?

Re: Viber adds end-to-end encryption

#56

Post by CiPHPerCoder »

goodplay wrote: post #54
CiPHPerCoder wrote: post #52

Earlier quoted context omitted.

Here's your proof: http://cs.au.dk/~jakjak/master-thesis.pdf See also: http://www.cryptofails.com/post/70546720222/telegrams-crypta... https://moxie.org/blog/telegram-crypto-challenge/

Is it cryptographicly broken or not? Can I read the plain text of the traffic I capture?

https://tonyarcieri.com/all-the-crypto-code-youve-ever-writt...

The word "broken" means susceptible to practical attack, and attacks aren't always of the "cryptanalyze the ciphertext and read the plaintext because you're a clever mathematician" variety.

For example: Padding Oracle Attacks. This is the most accessible explanation on-hand: https://twitter.com/SoatokDhole/status/720435675401744385

A padding oracle attack lets you decrypt a message by studying how the cryptosystem responds to garbage input. Without recovering the key.

iMessage had a compression oracle attack recently: http://blog.cryptographyengineering.com/2016/03/attack-of-we...

They didn't merely "read the plain text of the traffic [they] capture[d]". But these systems were still, quite badly, broken.

So what's my point? Telegram's protocol is susceptible to the same class of active attack. Thus, it is broken.

Re: Viber adds end-to-end encryption

#57

Post by nxzero »

mikeokner wrote: post #42
nxzero wrote: post #7

End-to-end (E2E) code needs to be open source and venders that don't agree to an audit should be considered insecure; holds true for What's App, which declined to allow their E2E code to be audited. Also, message metadata is still being leaked by all of these E2E implementations and needs to be fixed.

> Also, message metadata is still being leaked by all of these E2E implementations and needs to be fixed. Ricochet ( https://ricochet.im/ ) solves that problem using Tor hidden services. Desktop only at the moment AFAIK, though.

Are there any stats posted on the size of the network? (either from Tor or P2P network analysis)

Re: Viber adds end-to-end encryption

#58

Post by tptacek »

nxzero wrote: post #7

End-to-end (E2E) code needs to be open source and venders that don't agree to an audit should be considered insecure; holds true for What's App, which declined to allow their E2E code to be audited. Also, message metadata is still being leaked by all of these E2E implementations and needs to be fixed.

WhatsApp's "E2E" code is from Signal, which is open source.

This zealous belief that all secure cryptography must be open source is something I hear a lot from open source advocates, but not so much from cryptography engineers.

Re: Viber adds end-to-end encryption

#60

Post by robbiemitchell »

ikeboy wrote: post #48
Jtsummers wrote: post #40

Earlier quoted context omitted.

If a service offers a feature, it's within customers' rights to use that feature. If Viber is unilaterally deleting messages, that's an issue (as ephemeral messaging doesn't seem to be their primary intent). But if Alice is able to delete her messages to Bob on Bob's device, and both know this (or should know this, they chose the messaging platform), Bob has not had his rights violated. He's complying with Alice's re…

The comparison to Amazon is about the remotely deleting part, not the why part. I have a problem with anything on my device being deleted without my consent.

You used the word "sent" earlier and the phrase "on my device" now. But it seems the app isn't transferring the message to you, only presenting it -- like a website. (Does the message exist outside the app?)

Not being pedantic for the sake of it, just pointing out the language you are using is from a position of ownership -- you receiving and owning a message sent to you, and it is then being deleted -- while the app seems to be retaining all rights with the sender, who merely uses the app to present a message to you, and can revoke viewing privileges at any time.

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