4 ms·

The weird part about this - why does Signal let anybody access the same account with just a SMS verification? I would think it would be better to send the verif

by ufmace 4y ago

The weird part about this - why does Signal let anybody access the same account with just a SMS verification? I would think it would be better to send the verification message to be added to an account through their Signal account. Telegram does this already.

cesarb 4y ago
There will always be a tension between security and usability. A common situation is when a phone stops working (for instance, it fell into a puddle) or is lost or stolen. If it stops working, you can just pop the SIM and put it on a new phone (assuming the new phone accepts SIM cards of the same size, instead of requiring an even smaller one); if it's lost (or your SIM card is too big for the new phone), you can go to one of the phone company's stores, present your identity card, and get a new SIM card associated with the same phone number. Either way, you don't have access to the Signal account anymore, since it was on the broken/lost/stolen phone; the SMS verification (plus the optional password) is the only way to recover it.
- ufmace 4y ago
  I thought about that, and I'm not sure it actually changes anything. So you want to register a new device with your Signal account and you don't have the previous device, either because you're a malicious attacker or you lost or destroyed it. Covering the attacker case, presumably you already can't access the message history. I don't see how you could reasonably do anything different for the lost device case, but I guess it's not that big a deal to lose message history. But if the message history is already gone either way, why not make it a entirely new and separate account?
palata 4y ago
Because of their threat model. Signal has very good e2e encryption, but somebody could take over the account over SMS (note: they would not access any encrypted message, and that would reset the key so the contacts would know that a change happened and could verify the key if it matters for them). Telegram, on the other hand, is mostly not e2e encrypted, so their cloud can read all of your messages. Pick your favourite.
freeAgent 4y ago
I wish they’d decouple accounts from phone numbers, but to this point specifically, they do have a feature where you can add a PIN on your account that makes it impossible to re-register for some period of time (7 days? I forget). That’s at least enough to neutralize the risk from SIM swaps.

by ufmace 4y ago

cesarb 4y ago

There will always be a tension between security and usability. A common situation is when a phone stops working (for instance, it fell into a puddle) or is lost or stolen. If it stops working, you can just pop the SIM and put it on a new phone (assuming the new phone accepts SIM cards of the same size, instead of requiring an even smaller one); if it's lost (or your SIM card is too big for the new phone), you can go to one of the phone company's stores, present your identity card, and get a new SIM card associated with the same phone number. Either way, you don't have access to the Signal account anymore, since it was on the broken/lost/stolen phone; the SMS verification (plus the optional password) is the only way to recover it.

ufmace 4y ago
I thought about that, and I'm not sure it actually changes anything. So you want to register a new device with your Signal account and you don't have the previous device, either because you're a malicious attacker or you lost or destroyed it. Covering the attacker case, presumably you already can't access the message history. I don't see how you could reasonably do anything different for the lost device case, but I guess it's not that big a deal to lose message history. But if the message history is already gone either way, why not make it a entirely new and separate account?

palata 4y ago

Because of their threat model. Signal has very good e2e encryption, but somebody could take over the account over SMS (note: they would not access any encrypted message, and that would reset the key so the contacts would know that a change happened and could verify the key if it matters for them). Telegram, on the other hand, is mostly not e2e encrypted, so their cloud can read all of your messages. Pick your favourite.

freeAgent 4y ago

I wish they’d decouple accounts from phone numbers, but to this point specifically, they do have a feature where you can add a PIN on your account that makes it impossible to re-register for some period of time (7 days? I forget). That’s at least enough to neutralize the risk from SIM swaps.