4 ms·

That's true, but they provide means to verify the fingerprint of the other party, so you can verify that your app is encrypting messages using legitimate public

by M4v3R 11y ago

That's true, but they provide means to verify the fingerprint of the other party, so you can verify that your app is encrypting messages using legitimate public key and that there's no MITM going on.

dogma1138 11y ago
Yeah but again there are quite a few questions here (not an WA user). How foolproof is the verification system, how susceptible is it to downgrade attacks (while E2EE isn't not universally deployed) is there are 3d party verification of signatures, is there a community trust signing, can whats app disable E2EE in it's application without a noticeable UX change to either party, how does this work with multi user messages, how does this work with multiple devices, how does this work with historic messages that were encrypted using different keys etc. I would say that there are sufficient "unknowns" at this point to take the security of this entire solution with some skepticism especially if you remotely planning to use this for anything that could put your life at any risk.
- SAI_Peregrinus 11y ago
  Downgrade attacks should be difficult. As the article mentions once a client has communicated with another once using encryption all future communications to that client will be encrypted. So a downgrade attack would require either spoofing a new client for a user (eg a phone they didn't have before) which is likely noticeable. The whitepaper (https://www.whatsapp.com/security/WhatsApp-Security-Whitepaper.pdf https://www.whatsapp.com/security/WhatsApp-Security-Whitepap...) goes into more detail. That said, they could push out an update that changes the UI to disable E2EE without notifying the user, and that would be difficult to notice since the app is closed source. For this reason Signal is more secure, despite using the exact same protocol.

4 ms·

That's true, but they provide means to verify the fingerprint of the other party, so you can verify that your app is encrypting messages using legitimate public

by M4v3R 11y ago

That's true, but they provide means to verify the fingerprint of the other party, so you can verify that your app is encrypting messages using legitimate public key and that there's no MITM going on.

dogma1138 11y ago
Yeah but again there are quite a few questions here (not an WA user). How foolproof is the verification system, how susceptible is it to downgrade attacks (while E2EE isn't not universally deployed) is there are 3d party verification of signatures, is there a community trust signing, can whats app disable E2EE in it's application without a noticeable UX change to either party, how does this work with multi user messages, how does this work with multiple devices, how does this work with historic messages that were encrypted using different keys etc. I would say that there are sufficient "unknowns" at this point to take the security of this entire solution with some skepticism especially if you remotely planning to use this for anything that could put your life at any risk.
- SAI_Peregrinus 11y ago
  Downgrade attacks should be difficult. As the article mentions once a client has communicated with another once using encryption all future communications to that client will be encrypted. So a downgrade attack would require either spoofing a new client for a user (eg a phone they didn't have before) which is likely noticeable. The whitepaper (https://www.whatsapp.com/security/WhatsApp-Security-Whitepaper.pdf https://www.whatsapp.com/security/WhatsApp-Security-Whitepap...) goes into more detail. That said, they could push out an update that changes the UI to disable E2EE without notifying the user, and that would be difficult to notice since the app is closed source. For this reason Signal is more secure, despite using the exact same protocol.