Hi.

This is mostly a paranoia issue, but here goes anyway.

I haven't got a freenet node running at the moment, so my observations are 
only immediately based on a google search (sorry, didn't have the time 
recently to keep my node running). Is there a public Freenet node around 
that I could use for testing?

Here is what I have I have noticed. The Freenet's supposedly secure 
SSK keys (URLs) are 31 bytes long in the format that appears to be Base64 
encoded. That is fine. However, I have also noticed that the last 4 
entries seem to be repeated with conspicuous regularity. On sites 
referring to Freenet 0.3 the URLs seem to end with QAgE and in 0.4 with 
PAgM. I presume this is a "feature". This reduces the key size down to 28 
bytes.

128-bits = 16 bytes = 32 characters hex encoded = 20 character Base64 
encoded.

Am I to assume that these keys are about 128 bits long, with 8 bytes used 
for something else? Can anyone point me at the correct documentation on 
the subject?

>From what I understand from reading the documentation I found on the main 
web site, these keys are the same as the inverse of the standard 
public/private keys a-la PGP. Obviously, the situation is inverted because 
the files are world readable, but only writeable by the person with the 
correct key.

Anyway, elsewhere I have found that public/private key encryption 
suffers from weaknesses compared to standard symetri key encryption. So 
much so, in fact, that to achieve the equivalent of a 128-bit symetric 
security you have to use a key size of closer to 2500 bits. Does it not 
follow from that that a freesites' key could be discovered fairly easily, 
which would allow the site to be defaced, or replaced.

Or is the SSK effectively just an MD5 type hash produced from an actual 
key to provide a unique identifier for a site? If so, then fair enough, it 
is at least 128-bits big.

Can somebody please shed some light on this for me? A link to the correct 
documentation would be fine (with a page/chapter pointer even more 
appreciated).

Also, what key size is used for different things in Freenet? I have been 
getting a feeling lately that 128-bit isn't really paranoid enough for a 
network such as Freenet. Would 256-bit, or even 512-bit keys not be more 
suitable for future proofing? I am not talking about just data store 
keys, but about all of the keys. Or is this planned for the future, but 
largely left alone for now on the basis that the project is still in 
development and using larger keys would only slow things down needlessly 
at this stage?

Regards.

Gordan


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