Yes, I'd like to clarify Timeflake (and many alternatives suggested) is NOT meant to be used for security.
There's an important note on the readme about this:
> Since the timestamp part is predictable, the search space within any given millisecond is 2^80 random numbers, which is meant to avoid collisions, not to secure or hide information. You should not be using timeflakes for password-reset tokens, API keys or for anything which is security sensitive. There are better libraries which are meant for this use case (for example, the standard library's secrets module).
Leaking users private pictures / documents / whatever, will also kill a company.
I guess one could maybe circumvent this, by using a hash of the ID, but then you have to store that somewhere too, and you're back to square one.
Nevertheless, I like that you fixed the main flaw with ULID. Also you provide way better insight into the tradeoffs, so kudos!
Hashing the IDs won't solve their lack of entropy. Crude example: If you hash your pincode I still have only 10^4 values to try.
The easiest way to fix this is to add an access token column that is cryptographically random and use both the ID and the token in the URL.
If you trust the 80 bits already in the ID the token only needs to be 80 bits for a total of 160 bits of entropy. But if you do that you have to make sure that a missing ID and invalid token are handled identically from the attackers perspective (same reply, same timing).
Yes and no. It would still significantly largen the search space, as an attacker wouldn't get a point of reference to latch on to.
The spec doesn’t specify a source of randomness - an implementation that uses https://xkcd.com/221/ will or course not be a very good one.
They're not an edge case, in that the standard displays them quite prominently. They're actually the only code examples given.
The standard should deprecate them, because people WILL use them "wrong".
With purely random UUID, you can be pretty sure that nobody can guess them, so they're essentially identifier and access token in one.
However once you can easily predict the next uuid from the previous one (as by incrementing the random part by one), the access token property vanishes.
At least this proposal doesn't make the same mistake, however 80 bit's isn't THAT much entropy. (Remember every bit counts with exponential growth, and 48 bits less, means 281474976710656 times easier to guess.)
So it boils down to. Would you be ok to secure all your data with 10 character one time passwords, which might not be guessed all at once, but where guessing SOME is sufficient to get owned?
Death by a thousand paper-cuts.