Hi, just to be sure when understanding PIM. So what you are saying is, if the value of PIM is below 485 you are actually decreasing the strength of the setup? This seems crazy to me. How is this not warned with big letters during creation of a volume?
I mean, what if you have no idea and just type 20 or something?
By what do they say here, I understand that if your pass is less than 20 characters, then it will always use 485 minimum (even if you enter a lower PIM, it will override it and use 485 for iterations is what they mean?)
Well but what if your password is 20+ chars and you literally type 1 PIM? The way they phrase this here I understand that it actually weakens the encryption:
Motivations behind using a custom PIM value can be:
Add an extra secret parameter (PIM) that an attacker will have to guess
Increase security level by using large PIM values to thwart future development of brute force attacks.
Speeding up booting or mounting through the use of a small PIM value (less than 98 for system encryption that doesn’t use SHA-512 or Whirlpool and less than 485 for the other cases)
So the first point is obvious.. okay 3 more numbers for an attacker to guess. Is this relevant for someone with firepower to bruteforce? I guess it helps.
The second point, I understand you increase protection against bruteforce, as long as it’s longer than 98 or 485 for sha256/sha512.
The third point is what seems shocking. It basically means, use a lower value to decrypt faster (because your encryption protection is weaker). And they should remind that this applies only to passwords shorter than 20 characters if I understood this correctly above. But in any case.. what’s the deal here? I guess most people use around 20+ chars, so this PIM value will have a role in the strength of the encryption. If you go in there on the VeraCrypt volume creation wizard, you are not told that if you enter a value lower than 98 or 485 for sha256 and sha512 respectively, you are actually decreasing the strength of the encryption… wtf. I mean what if you enter a really low value and you have no idea about this? This is pretty lame tbh. Well at least you can tweak the PIM value it seems without having to redo the entire thing (or maybe you do because on the screenshot it looks like it wipes the contents)
I think this wizard should warn the user about this, because one just assumes this is just like a regular PIN number, just 3 numbers that have no impact on the encryption, certainly not potentially decreasing it.
This also adds an interesting/odd dynamic here… like, how many people may just put 999 in there because it’s the max security. So what if someone guesses the 999 number right? Isn’t this less safe than a lower less obvious value? For an attacker it also potentially shortens the number of values from 485 and below because most people may not want to decrease but increase the effectiveness of the encryption (so an attacker has less numbers to guess is what I mean). Just considering all possible angles of this, hope it makes sense?