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WhatsApp's Signal Protocol integration is now complete

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Re: WhatsApp's Signal Protocol integration is now complete

#181
post #96
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. // edit: got my answer here: https://news.ycombinator.com/item?id=11432629 I'm curious, is that because of what they did in the FBI case, or for technical reasons? IIRC iMessage would allow Apple to add public keys which they (or the FBI/$ADVERSARY) control as a sort-of backdoor as well. I can't say that I…

The unfortunate reality too is that average users will never go to the extra trouble of authenticating keys themselves. I'm also more likely to trust a company like Apple or Google with key management than a "trusted third party" (simply because they're bigger companies, with more valuable brands to protect, and resources to throw at the problem).

So, it feels like for the average consumer, a product like iMessage ticks all the necessary boxes. While WhatsApp adding features like the ability to compare your keys via a QR code looks cool, I have to wonder how many users will actually take advantage (and how would they even know if that number or QR code really represents what they think it does?)

Re: WhatsApp's Signal Protocol integration is now complete

#182
Cool! Though am I the only one wondering how this fits into FB's plans? I suppose they still get all contacts and know how frequently I contact them, which builds very valuable info. (Something MSN Messenger never leveraged, sigh.) I'm still very hesitant about ever trusting anything to FB.

Apparently by default there's no notification of changed keys: "WhatsApp users can opt in to a preference which notifies them every time the security code for a contact changes". I guess the question is, does this preference get sent to the server or exposed any other way? If it doesn't then it might be too risky to use this as an attack channel.

Re: WhatsApp's Signal Protocol integration is now complete

#183
Does this include file transfers, if so, how?

Curious because when sending a .webm video from an Android device to a iOS device, the video file was transcoded on WhatsApp servers and then delivered to the iOS device as H264/mp4 (since iOS can not play .webm files)

This should no longer be working.

Re: WhatsApp's Signal Protocol integration is now complete

#184
post #140

How does this compare with Telegram?

By default, Telegram stores a plaintext copy of every message you've ever sent or received on their servers. WhatsApp does end to end encryption using the Signal Protocol by default, and doesn't store anything server side.

When you say Telegram servers store plaintext "by default", does that imply this is not also true of their "Secret Chat" feature? That mode appears to behave as if it's exchanging keys and doing end-to-end encryption... (I am aware of the Telegram flaws you and others have pointed out).

Re: WhatsApp's Signal Protocol integration is now complete

#185
post #159

Earlier quoted context omitted.

Then demand reproducible builds from software with security claims?

Can I have serious cryptanalytic audits first? Because virtually nothing has that. At least I trust what Signal Protocol is trying to do!

One does not preclude the other. For instance, the current Signal implementation is almost certainly prone to remote code execution.

How does the Signal project handle reports of potential vulnerabilities? I haven't seen any security contact information on the OpenWhisperSystems site.

Re: WhatsApp's Signal Protocol integration is now complete

#186

Earlier quoted context omitted.

agreed, i had no idea. i am humbled.

What's worse is that I am nowhere close to the best crypto security person on HN, and (unlike me) the best crypto people here don't brag about it.

Could you share some links about Snowden & Cryptocat story you mentioned above?

Re: WhatsApp's Signal Protocol integration is now complete

#187

Earlier quoted context omitted.

What's more, my client says "You aren't secure because X needs to upgrade WhatsApp", but the other party is seeing "you are secure", complete with fingerprint and everything. I wonder which of the two devices is lying.

I hit the same thing - I think my client just had a stale view of what version the person I was talking to was running. I did a refresh of the Favorites list on iOS and it sorted it out.

Same issue and this resolved it. Thanks for posting that.

Re: WhatsApp's Signal Protocol integration is now complete

#188
post #87
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…

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…

What are WhatsApp's tradeoffs in favor of adoption and usability, compared to Signal?

Re: WhatsApp's Signal Protocol integration is now complete

#189
post #123

Earlier quoted context omitted.

> 12 words seems so much more friendly, at least to English speakers I have a feeling that English speakers are the minority of WhatsApp users. > if you don't speak a common language with your chat partner then the app is useless anyway They do speak a common language, it's usually just not English.

And the language of the clients might not be the same. I might write in English to a German friend, but my whatsapp is localized to Danish and his to Germany. How would whatsapp know what language to present the words in?

It could be a selectable option.

Re: WhatsApp's Signal Protocol integration is now complete

#190
post #164

Earlier quoted context omitted.

I would place Signal in the same tier as WhatsApp here (Tier 2). They both upload your contacts to an intermediate server that gives you their public key, which you can optionally verify afterwards. This means a malicious server could both store away your contacts and try to MITM you, risking detection if you do verify your fingerprint with the other party. A messenger that really did "all possible tradeoffs in favor…

That's something that's at least somewhat true of OTR and PGP too, in their normal use, and in all three cases if you're serious about OPSEC you can completely mitigate the problem. So in my evaluation, Signal's a tier 1 option, and WhatsApp is tier 2. Reasonable people can disagree, of course. I hope it's obvious that, since OTR is in tier 1, these tiers aren't an analysis of how much I like different messengers. :)

> That's something that's at least somewhat true of OTR and PGP too

Well, OTR is just the protocol, implementations vary in how well they make you authenticate your conversation partner. And PGP will whine at you a lot if you haven't marked a key as trusted. But somewhat agreed. A bad UI can ruin the security of otherwise solid crypto.

I just don't see how the security of Signal and WhatsApp are different. Assuming for a moment (very optimistically) that the user verifies the fingerprint and enables the alert for changed keys, they are using the same protocol with the same guarantees.

Are you factoring in some level of trust in their ability to write a secure client or run secure servers?

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