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Comment by londons_explore | Hacker News Reader

The Whatsapp binary is sufficiently transparent to enable someone determined to write their own client. Thats enough info for an expert to verify their "messages are end to end encrypted and we don't know the key" claim.

The fly in the ointment is the client might have additional functionality to leak the e2e encryption key. That is far harder to find, but if it's use were widespread, it would be found by researchers.

The whole point is moot though - whatsapp is designed to (by default) upload cleartext chat logs to google/apple servers. Since all chats have 2+ recipients, the conversation is only safe from snooping if nobody in the chat has backup enabled, which is unlikely.

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Yep, the chat log backup basically renders WhatsApp completely insecure. They also constantly nag you inside the app to enable it. This is how they caught Michael Cohen (and presumably others). Unfortunately Signal does it, too.

Signals backups are encrypted.

And local.. whatsapp tries to get you to send unencrypted backups to google drive.

How are they restored? Is it password-encrypted?

you copy them to your new phone. yes.

Yes, you're given a random password when you enable backups that you need to use when restoring. They don't get uploaded to the cloud. On iOS there's no backup feature at all AFAIK.

I don't think that Signal uploads the backups to the cloud though. It seems like they're stored on device and encrypted.

At least on iOS - whatsapp doesn't seem to nag about backups (i don't think i've ever enabled it), but you can do a local backup/restore if you replace handset. Signal encrypts your chats locally (but not binary blobs/video/images) but they cannot be backed up and restored locally.

Attack or cooperation with custom soft keyboard makers is much easier. It may only give you one side of the conversation but no ones seems to care if those are secure. As long as they do a good job of spell checking.

Having a 'secure' conversation definitely implies trust in Google/Apple, regardless of the Whatsapp binary behaving flawlessly (e2e encryption, solid PRNG, no logs etc.)

They could indeed serve you a different binary from the app-store. "Do you think that's Whatsapp you're using?"

Trust in the OS made by Google/Apple is slightly different from trust in the ability of Google/Apple to keep your data stored on their servers secure against nation states.

I have much more trust in the former than the latter.

It doesn't have to be whatsapp that "steals" the key, we have zigote and google play services to do that.

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