4 ms·

That's good, but I don't see how that means we know they aren't being stored. The NSA or another entity could be collecting them in bulk just in case the encryp

That's good, but I don't see how that means we know they aren't being stored. The NSA or another entity could be collecting them in bulk just in case the encryption is broken in 30 years.

cvwright 4y ago
What’s your alternative? Sneakernet? Anything that goes over a network could be stored.
- scifibestfi 4y ago
  The article says they are not stored. That's what I'm questioning. "user messages are stored only on their devices, not on Signal’s servers or anywhere else."
  - kingaillas 4y ago
    I think it is fair to interpret that as: Signal is not storing messages on their servers, also Signal is not storing them on someone else's servers. Whether or not a 3rd party, outside Signal's knowledge and/or control, is storing messages is entirely out of their control.
  - tialaramex 4y ago
    Sure, like I said, it's a information theoretic argument. Imagine if Signal used a One Time Pad instead of AES, this might make it easier to see what's going on if you have some idea about the One Time Pad. Suppose I promise you that qMsVOrgWDZTo0Fet9xLhIQ is the base 64 encoded, 16 byte encrypted message I just sent, but I used OTP. Do you in some sense "have" a copy of my message ? No. That is completely useless without the key, it could have literally been any message, without the key there's no difference.
    - scifibestfi 4y ago
      Thanks for the explanation! That helps.
  - palata 4y ago
    The whole point of e2ee is that you don't have to care about that!
tptacek 4y ago
That's true of literally every possible messenger application.
tialaramex 4y ago
So, the first time we standardised symmetric encryption was DES in 1977. DES was at that time already known to have keys which are too small (56 bits) and blocks which are too short (64 bits) to be safe against a powerful attacker (like, say, the US government) but it appeared otherwise to be a good design. The algorithm actually has one flaw in its pre-DES existence, unsuspected by academics, but which the NSA had in fact fixed in DES because they knew about it. And sure enough, even today the most practical attacks on DES are in effect brute force on those too-small keys and too-short blocks - this brute force is practical although very expensive. Now, in 2001 DES was superseded by AES, which is used for this purpose by Signal. In AES the keys are larger (128, 192, or 256 bits, Signal uses 256) and the block size is longer too (128 bits), thus fixing the only problem DES still had. We are done. So, while of course nobody can prove it won't happen in 30 years, it is extremely unlikely. You might think to yourself, surely computers get faster and smaller, so the brute force problem would still arise maybe in a few decades? Nope. In the late 20th and early 21st century humans experienced something that's only going to happen once, and it has distorted our perspective on the matter. The machines are not, in fact, going to keep getting faster and smaller, there are physical limits imposed by the universe. They will get gradually a bit faster than they are now, and we will make a lot more of them, but nowhere close to enough even if (for some insane reason) our civilisation decided its only goal is to decrypt my old Signal messages.

That's good, but I don't see how that means we know they aren't being stored. The NSA or another entity could be collecting them in bulk just in case the encryption is broken in 30 years.

cvwright 4y ago

What’s your alternative? Sneakernet? Anything that goes over a network could be stored.

scifibestfi 4y ago
The article says they are not stored. That's what I'm questioning. "user messages are stored only on their devices, not on Signal’s servers or anywhere else."
- kingaillas 4y ago
  I think it is fair to interpret that as: Signal is not storing messages on their servers, also Signal is not storing them on someone else's servers. Whether or not a 3rd party, outside Signal's knowledge and/or control, is storing messages is entirely out of their control.
- tialaramex 4y ago
  Sure, like I said, it's a information theoretic argument. Imagine if Signal used a One Time Pad instead of AES, this might make it easier to see what's going on if you have some idea about the One Time Pad. Suppose I promise you that qMsVOrgWDZTo0Fet9xLhIQ is the base 64 encoded, 16 byte encrypted message I just sent, but I used OTP. Do you in some sense "have" a copy of my message ? No. That is completely useless without the key, it could have literally been any message, without the key there's no difference.
  - scifibestfi 4y ago
    Thanks for the explanation! That helps.
- palata 4y ago
  The whole point of e2ee is that you don't have to care about that!

tptacek 4y ago

That's true of literally every possible messenger application.

tialaramex 4y ago

So, the first time we standardised symmetric encryption was DES in 1977. DES was at that time already known to have keys which are too small (56 bits) and blocks which are too short (64 bits) to be safe against a powerful attacker (like, say, the US government) but it appeared otherwise to be a good design. The algorithm actually has one flaw in its pre-DES existence, unsuspected by academics, but which the NSA had in fact fixed in DES because they knew about it. And sure enough, even today the most practical attacks on DES are in effect brute force on those too-small keys and too-short blocks - this brute force is practical although very expensive. Now, in 2001 DES was superseded by AES, which is used for this purpose by Signal. In AES the keys are larger (128, 192, or 256 bits, Signal uses 256) and the block size is longer too (128 bits), thus fixing the only problem DES still had. We are done. So, while of course nobody can prove it won't happen in 30 years, it is extremely unlikely. You might think to yourself, surely computers get faster and smaller, so the brute force problem would still arise maybe in a few decades? Nope. In the late 20th and early 21st century humans experienced something that's only going to happen once, and it has distorted our perspective on the matter. The machines are not, in fact, going to keep getting faster and smaller, there are physical limits imposed by the universe. They will get gradually a bit faster than they are now, and we will make a lot more of them, but nowhere close to enough even if (for some insane reason) our civilisation decided its only goal is to decrypt my old Signal messages.