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WhatsApp's Signal Protocol integration is now complete

whispersystems.org

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Re: WhatsApp's Signal Protocol integration is now complete

#111

Post by criddell »

jamesdwilson wrote: post #80
zxexz wrote: post #79

Earlier quoted context omitted.

That's not necessarily true. I haven't spent much time analyzing it yet, but your assertion seems seems. Please correct me if I'm mistaken, but can't you verify end-to-end encryption without viewing the source of the program? They're using the Signal protocol, which has been well-vetted. What I've seen so far in Wireshark looks good, but I am not a crypto expert. I'm in the process of reading and trying to understand…

without the source, it is not verifiable. it could be making a copy and sending it in an encrypted side-channel for example to their overlords.

> without the source, it is not verifiable

And would you also claim that without the source, you can't find security problems?

Re: WhatsApp's Signal Protocol integration is now complete

#112

Post by hannob »

pilif wrote: post #59

What the article fails to mention: 1) I would assume Facebook still gets unencrypted access to my address book for use with their shadow profiles 2) We have zero control over what key the client encrypts the messages for. Is it only the other peer's phone? Or is it for the peer's phone plus Facebook for analysis of the messages? Especially 2) is of some concern to me (against 1 I can't protect myself anyways because…

> From that perspective, I'm still inclined to trust apple's iMessage a bit more especially after recent events.

I'm surprised by this statement. After recent events I'd say the imessage protocoll is a weird ad-hoc construction that failed to follow basic modern crypto constructions like authenticated encryption and forward secrecy. I don't expect anything alike from the signal protocol.

Re: WhatsApp's Signal Protocol integration is now complete

#113

Post by tptacek »

swombat wrote: post #108
tptacek wrote: post #87

Earlier quoted context omitted.

I think this is a reasonable analysis. I would refine it this way (examples are only for illustrative purposes): Tier 1 secure messengers: all possible tradeoffs in favor of security made; use for worst-case adversaries: - Signal/TextSecure - Pond - PGP† - OTR Tier 2 secure messengers: serious secure messaging protocols that make some tradeoffs in favor of adoption and usability; use for normal messages of low sensit…

> - Redacted to avoid flamewars. Aww... shucks.

My Twitter mentions are noisy enough already this week. :)

Re: WhatsApp's Signal Protocol integration is now complete

#114

Post by amluto »

Is it still the case that verifying a user's text identity does not verify their voice identity and vice versa?

IMO it would be very nice if calling someone and verifying the short code would confirm their text identity as well and if, once someone's text identity is verified, if voice calls to that person were protected by the verified text identity.

(IIRC the reason that Signal does not work this way is that texts use Axolotl whereas voice uses ZRTP and the key material is completely independent.)

Re: WhatsApp's Signal Protocol integration is now complete

#115

Post by kasey_junk »

humanrebar wrote: post #99
zxexz wrote: post #82

Earlier quoted context omitted.

Doesn't everyone in the chat have to have the new version of the app before it's all e2e?

I guess? Hence the indicator. It would be nice to know if someone switched phones and e2ee turned off, for example.

> Once a client recognizes a contact as being fully e2e capable, it will not permit transmitting plaintext to that contact

They do this to prevent degradation attacks.

Re: WhatsApp's Signal Protocol integration is now complete

#116

Post by stormbrew »

avn2109 wrote: post #91
stormbrew wrote: post #53

Earlier quoted context omitted.

It seems like there could be a lowest-common-denominator set of phonemes that such a system could be built on, with translations into symbol groups for different languages. As long as those symbol groups are relatable by two people who speak the same language, that might be sufficient?

>> "lowest-common-denominator set of phonemes" They already spent a bunch of time and effort finding these phonemes to build Esperanto, right?

That would probably still be a very eurocentric set of phonemes, so probably would not really be suitable for the modern multilingual world, I would think.

Re: WhatsApp's Signal Protocol integration is now complete

#117

Post by jamesdwilson »

swombat wrote: post #110
jamesdwilson wrote: post #107

Earlier quoted context omitted.

fair enough! https://www.schneier.com/blog/archives/2016/03/possible_gove... i think this is why source is a must. if a user compiled and installed the app themselves, and hypothetically had the entire stack above it be similarly open, then it would prevent the kind of attack mentioned. do you agree? if the source is closed anywhere in the stack, or pushed out in a walled garden as it is currently, then it allows the…

Just in case you don't know, tptacek is a world-class security/cryptography expert who happens to hang around and share his wisdom here. You appear to be assuming he's someone thinking one or more levels lower than you. I think it would be smarter for you to assume that he fully understands your argument but is thinking one or more levels higher than you.

agreed, i had no idea. i am humbled.

Re: WhatsApp's Signal Protocol integration is now complete

#118

Post by pilif »

hannob wrote: post #112
pilif wrote: post #59

What the article fails to mention: 1) I would assume Facebook still gets unencrypted access to my address book for use with their shadow profiles 2) We have zero control over what key the client encrypts the messages for. Is it only the other peer's phone? Or is it for the peer's phone plus Facebook for analysis of the messages? Especially 2) is of some concern to me (against 1 I can't protect myself anyways because…

> From that perspective, I'm still inclined to trust apple's iMessage a bit more especially after recent events. I'm surprised by this statement. After recent events I'd say the imessage protocoll is a weird ad-hoc construction that failed to follow basic modern crypto constructions like authenticated encryption and forward secrecy. I don't expect anything alike from the signal protocol.

The one thing iMessage and WhatsApp have in common is that they both end-to-end encrypt without giving the user control over the keys being used.

So ignoring actual protocol and implementation flaws (I agree with you that WhisperSystems will probably be ahead of Apple there), both rely on the key management being done in a thrustworthy manner.

And this is where I trust Apple more than Facebook, especially in light of the recent FBI events. If Apple says they are not maliciously injecting fake public keys for the purpose of surveillance and marketing, I tend to believe Apple.

If Facebook is silent about this, I assume they are doing it.

Re: WhatsApp's Signal Protocol integration is now complete

#119

Post by tptacek »

jamesdwilson wrote: post #107
tptacek wrote: post #92

Earlier quoted context omitted.

You keep saying "source is a must" but you have yet to explain why that is the case.

fair enough! https://www.schneier.com/blog/archives/2016/03/possible_gove... i think this is why source is a must. if a user compiled and installed the app themselves, and hypothetically had the entire stack above it be similarly open, then it would prevent the kind of attack mentioned. do you agree? if the source is closed anywhere in the stack, or pushed out in a walled garden as it is currently, then it allows the…

I understand what you're saying. I don't think source is bad thing! Source is good.

But I think you're a little confused here.

The cryptographic building blocks of the new WhatsApp protocol are available in source code. You can get source for the Signal Protocol (fka Axolotl). You can get source for the Noise framework. WhatsApp borrowed these tools from a very open secure messaging project.

You're unhappy that the source code for the fully assembled messaging product WhatsApp isn't available. I understand that, too.

But you've overplayed your hand by arguing that not releasing WhatsApp source is fatal to its security. Even if WhatsApp had done that, the overwhelming majority of its users (in fact: basically all of them) would be installing binaries. If WhatsApp is so evil that they've backdoored their product, it is "supervillain monologuing for an hour while the hero escapes"-grade stupid to leave that backdoor in their source code. Consider that carefully when you trust binaries from open source companies, by the way!

In reality, source code does very little to resolve the government backdoor problem. If you want to ensure that your secure messenger hasn't been backdoored, reverse engineer and/or instrument the build you're actually running.

Nobody does this, of course. But while lots of people glance at source code for crypto applications, I think they're pretty much just kidding themselves. Having the source code makes them feel safer, but it doesn't actually make them safer.

Re: WhatsApp's Signal Protocol integration is now complete

#120

Post by dewey »

mtgx wrote: post #81
moxie wrote: post #20

Earlier quoted context omitted.

> They seem to have replaced TLS/SSL between client and server with "Noise Pipes". WhatsApp was already using a custom protocol instead of TLS. We worked with them to transition over to Noise Pipes, which has some advantages over what they were doing before. Also, we've renamed Axolotl to Signal Protocol: https://whispersystems.org/blog/signal-inside-and-out/

Moxie, what do you say to this? https://twitter.com/JZdziarski/status/717399098563891200 Is that true? Are the messages decrypted server-side for iOS users?

He said: https://twitter.com/moxie/status/717403659298942976
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