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It reads like they said what they meant.

The hashes cannot be used to obtain access to the folder; it is just a way to discover the IP addresses of devices with the same folder. Hashes also cannot be guessed; it is a 160 bit number, which means that it is cryptographically impossible to guess the hash of a specific folder.

That is, you can only know the hash of a specific folder if

a. You have that folder

b. Someone told you the hash

This follows from using any reasonable hashing algorithm, such as sha-1.

Furthermore, because the range of the hash is sufficiently large the chance that you can, guessing randomly, find a valid folder is quite small.

There are 2^160 ~= 1.46 x 10^48 possible hashes.

Given that the probability of guessing a random folder is (number of folders hashed) / (number of possible hashes), and assuming that there are less than 10^8 folders that have been hashed, the chance of randomly finding any folder is less than 1 in 10^40.



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