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Signal WhatsApp Chats Import

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Re: Signal WhatsApp Chats Import

#241

Post by jakub_g »

princevegeta89 wrote: post #211

I have a UI issue with signal, but other than that I think the app is rock solid. I openly write and send passwords and credit card numbers to my wife from time to time. The interface can look better, and it would be great if it can automatically backup all messages and media to the cloud and encrypt it. There is also this annoying "verify pin" popup that shows up once in a while.

> There is also this annoying "verify pin" popup that shows up once in a while.

Settings > Privacy > PIN reminders and you can disable that (at your own risk)

Re: Signal WhatsApp Chats Import

#242

Post by feanaro »

KAMSPioneer wrote: post #198
dwohnitmok wrote: post #184

Earlier quoted context omitted.

Chat history isn't immediately at odds with PFS. As I see it PFS first and foremost is for protecting messages in transit. This is to prevent dragnet-style surveillance. Chat history means giving up some measure of at-rest security, but it has no impact on the in transit part. Personally I also think some compromise of at-rest is a reasonable trade-off for a lot of consumer contexts because physical capture of your d…

But PFS is specifically about including "my adversary may, at a later date, compromise my private key" in your threat model without giving up plaintext. If we assume that calculating a private key from the public key is ~impossible (which I hope you agree we can do), and we further assume the private key never leaves the device, then forward secrecy is what lets us know the only way to get plaintext is by stealing it…

> Just protect your private key.

This is what PFS is all about: it is about noticing that keeping your private key secret is really hard and admitting you're probably not going to be able to do it.

But even so, when it leaks, the attacker won't be able to use it to unlock the ciphertexts of all your previous conversations that he meticulously recorded. This property is PFS.

There is no need for the attacker to have access to your device in order to execute this attack against systems which don't have PFS.

Re: Signal WhatsApp Chats Import

#243

Post by AshamedCaptain »

Evidlo wrote: post #171
dopu wrote: post #148

Earlier quoted context omitted.

Are these things so important that we should give up the easier maintainability (and potentially, security) that comes from centralization and the standardization of user clients? I absolutely think projects like Matrix are worthwhile, but it seems foolish to me to argue that there are no benefits that come from doing things the way Signal does. Besides, as sexy as decentralization is, in the wild it is not really pr…

> Mastodon is decentralized, but last I heard ~50% of users were on 3 nodes I would argue that the user distribution does not matter. What's important is eliminating network effects, which you get with federation. I think most people would consider email a successful federated service, and yet far more than half of users are only on the biggest three servers. https://www.zdnet.com/article/whos-the-biggest-u-s-e-mail-…

I agree: if say the 3 nodes used different implementations, this would basically be an ideal situation.

I don't know about Mastodon's case, but in Matrix the extremely low popularity of alternative servers is kind of a big roadblock.

Re: Signal WhatsApp Chats Import

#244

Post by cromka »

izacus wrote: post #46
_l4jh wrote: post #19

I have been using Signal for two years now and I love it. However I really, really hope they can work on a good backup and restore process as losing my message history because I have to reinstall the app on my desktop[1] or have to reset my phone is a horrible experience. Just build an encrypted blob and zip it up and pop it on my iCloud or Google Drive or leave it local and let me deal with it but I need something .…

> However I really, really hope they can work on a good backup and restore process as losing my message history because I have to reinstall the app on my desktop[1] or have to reset my phone is a horrible experience. I've tried to report bugs and talk to developers about this but there's one fundamental problem here - the Signal team fundamentally does not value chat history the same way a lot of people do. They thin…

This answer from their AMA on Reddit from 3 hours ago makes it sound that they are very aware of the issue and working on resolving it:

https://www.reddit.com/r/technology/comments/kt91qk/signal_p...

Re: Signal WhatsApp Chats Import

#245

Post by KAMSPioneer »

darkwater wrote: post #234
KAMSPioneer wrote: post #198

Earlier quoted context omitted.

But PFS is specifically about including "my adversary may, at a later date, compromise my private key" in your threat model without giving up plaintext. If we assume that calculating a private key from the public key is ~impossible (which I hope you agree we can do), and we further assume the private key never leaves the device, then forward secrecy is what lets us know the only way to get plaintext is by stealing it…

> But PFS is specifically about including "my adversary may, at a later date, compromise my private key" in your threat model I'm no crypto expert but that "later date" when talking about PFS is to avoid an external dragnet recording all your ciphered streams and then deciphering them once they have your non-PFS secret key. I mean, in your definition basically all the messages should be ephemeral on your device and o…

I'm comparing two scenarios:

In the first, a global adversary (say, NSA) records all your interactions via a chat service. This chat service does not use PFS. At a certain point, they capture the private key from one of your devices that uses the service, and is able to decrypt all your messages.

In the second, the same global adversary records all your messages, but this time from an otherwise identical service that DOES use PFS. The adversary captures your private key but can only use it to MitM attack you going forward. However, before discarding your device, they check your conversation history -- because your diligent backup and transfer of all your conversations since you signed up for the chat service, they now have all your messages. PFS did not help.

Now, you could change scenario #2 to where you don't have an option to back up and transfer message history (or simply choose not to), and that's essentially Signal. In that case, the adversary is pretty much hosed except for the messages your device just happened to have on it. Adversary steals message backup == adversary steals private key w/o PFS

Re: Signal WhatsApp Chats Import

#246

Post by charwalker »

FalconSensei wrote: post #133
izacus wrote: post #46

Earlier quoted context omitted.

> However I really, really hope they can work on a good backup and restore process as losing my message history because I have to reinstall the app on my desktop[1] or have to reset my phone is a horrible experience. I've tried to report bugs and talk to developers about this but there's one fundamental problem here - the Signal team fundamentally does not value chat history the same way a lot of people do. They thin…

> the Signal team fundamentally does not value chat history the same way a lot of people do This is the core problem as why many projects don't get mainstream. They have 2 options: they can focus on what they think is a priority, or on what the public thinks is a priority. I'm not saying Signal is wrong on doing what they are doing, as they are being successful among some niches (i.e: tech). But to grab Whatsapp user…

Telegram is really good for this, in my experience, and similar to Signal.

But you're right, Signal is designed for secure communication between parties. Allowing messages to be exported or archived should at worst leave only your own messages (and remove all others including media) and at best not exist at all.

Sure, let me just single handedly backup our conversation and send it to the HK police...

Re: Signal WhatsApp Chats Import

#247

Post by smichel17 »

KAMSPioneer wrote: post #178
beezle wrote: post #158

Earlier quoted context omitted.

>Keeping around old messages more or less negates the value of forward secrecy. Why? Can you please explain as my understanding of perfect forward secrecy is that should not matter. I'm not a crypto expert so perhaps I've overlooked something?

I mean, from the perspective of the crypto it doesn't matter. But it defeats the point of building a forward-secret system. Think of it like this: if I'm an attacker that breaks into the forward-secret chat app on your device, and you have kept a perfect record of every conversation you've ever had using that crypto system in _the same place you keep your identity keys_, then does it really matter whether the messagi…

> you have kept a perfect record of every conversation you've ever had

The other side of this coin is deniability. If you break into my secure location and steal my chat logs, but you can't tell which are real and which are fake, you've still got work to do.

The Signal protocol has you covered, here. After the fact (ie, as long as you don't watch me receive the message), there is no way to cryptographically prove which of the two participants wrote the message[0]. Thus, it is technically possible to forge a bunch of chat history, or claim that someone else's is forged. Cryptographically, the "spirit of forward secrecy" is secure.

That said, this is far out of the reach of the average person. Even if the only evidence is a screenshot, that conversation probably happened. So in practice yes, you've got a point. That's why I think it would really behoove Signal to add a "forge a conversation" feature. Make it trivial for either person to add a message to their local history that looks like it came from any of the participants, at a specific date/time. Now you've got practical deniability, too.

[0] https://signal.org/docs/specifications/x3dh/#deniability

Re: Signal WhatsApp Chats Import

#248

Post by charwalker »

FalconSensei wrote: post #220
freeone3000 wrote: post #216

Earlier quoted context omitted.

I fundamentally distrust any program which claims E2E encryption and is capable of recovering my chat history onto a new device. This means that Telegram is technically able to recover my chat history, making the "E2E" bit of the encryption smoke-and-mirrors.

I can be wrong, but on Telegram E2E is not default. Those are used only in 'secret chats', which I believe are not recoverable. So you can use regular texting for everything you don't care much about, like sending youtube videos and memes to your friends, and use the secret chat to things that re more sensitive. That's great for most people that currently use Whatsapp

Not my field but: https://core.telegram.org/api/end-to-end

Re: Signal WhatsApp Chats Import

#249

Post by KAMSPioneer »

feanaro wrote: post #242
KAMSPioneer wrote: post #198

Earlier quoted context omitted.

But PFS is specifically about including "my adversary may, at a later date, compromise my private key" in your threat model without giving up plaintext. If we assume that calculating a private key from the public key is ~impossible (which I hope you agree we can do), and we further assume the private key never leaves the device, then forward secrecy is what lets us know the only way to get plaintext is by stealing it…

> Just protect your private key. This is what PFS is all about: it is about noticing that keeping your private key secret is really hard and admitting you're probably not going to be able to do it. But even so, when it leaks, the attacker won't be able to use it to unlock the ciphertexts of all your previous conversations that he meticulously recorded. This property is PFS. There is no need for the attacker to have a…

Sorry, I'm probably explaining myself poorly. I much prefer chat systems with PFS because it mitigates the blast radius of a key leak, I get that. What I'm saying is, if you store a message history that contains the plaintext that Mallory wants, and it's stored in the same way the identity key is, PFS doesn't get you much.

The attacker who has all your ciphertexts needs the decryption key to get the plaintext (which she wants). Now, with a PFS scheme the key gets deleted as soon as I receive and decrypt the message, so the attacker is out of luck, basically (even if she gets my long-term key). However, PFS only moves the target to my plaintext message database...which is stored the same way my key is (as I understand it). So really, unless I purge my message history with some regularity (I do), then the stakes are the same -- don't let the attacker get access to the device.

But most people prefer to have all their chat history available and searchable, at which point individual decryption keys don't matter and therefore PFS doesn't, in my opinion, help much.

Re: Signal WhatsApp Chats Import

#250

Post by charwalker »

FreakyT wrote: post #5

The issue with Signal that annoys me most is the complete lack of any meaningful backup/export on iOS. I lost my entire chat history when I got a new phone because their bizarre "proximity based" solution failed.

Yes, I'll just backup our chat and send it over to the HK police.

At worst a backup from Signal should only be your messages and at best it should not exist. Signal is designed for secure communication not archiving communications you wish to be secure. If you want a texting app try Telegram or something more focused on user experience vs secure communication.

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