11 ms·

I don't understand quite, why so much brute force?

• detaro 11y ago
  The onion-name is a hash of the public key the service uses, so you can't just pick a name and use it. They had to try many keypairs to find some that hashed to "facebook...." (Normally you generate your key and just use whatever name that hashes to, but it's cool to have one that's easy to remember)
• p4bl0 11y ago
  The name of .onion address is the hash of a public key, so you can't choose it, or rather the only way is to generate random public and private key pairs and to keep the one that interest you. Facebook must have generated an awful lot of key pairs to get "facebookcorewwwi". By the way, I hope they deleted the other generated pairs…
  • bostik 11y ago
    I have good faith that they didn't, or certainly not all of them. When Alex described the entire process they went through, he also smirked that should that primary key ever get compromised they have several others, almost as good, ready as drop-in replacements. I do think he also mentioned that they only cared about keys that had their required prefix; all others were destroyed without anyone ever having access to them.
    • p4bl0 11y ago
      > I do think he also mentioned that they only cared about keys that had their required prefix; all others were destroyed without anyone ever having access to them. Okay, that is what I was implying would be terrible otherwise. But actually it is quite obvious that they would not spend the disk space necessary the keep every single generated key pairs now that I think about it.
      • jsprogrammer 11y ago
        How would that be terrible?
        • deleted 11y ago
          [deleted]
        • p4bl0 11y ago
          The number of generated key pair to find "facebook" + keywords must have been gigantic, maybe even so much that it could be used as a kind of rainbow table which would allow people (or three letters agencies) who can access it to attack hidden services that use one of the .onion for which a corresponding private key is known.
          • baby 11y ago
            This is not vulnerable to brute-force nor rainbow tables.
          • besselheim 11y ago
            Relative to the 2^80 (1,208,925,819,614,629,174,706,176) possible onion addresses, whatever they generated would be miniscule.
            • p4bl0 11y ago
              Indeed. I was being stupid and didn't take the time to really think it through. Thanks to you and all the others who pointed that out :).
          • shanemhansen 11y ago
            Presumably those 3 letter agencies also have the technology to generate RSA keys.
          • jsprogrammer 11y ago
            That shouldn't matter. If the scheme is vulnerable when some company generates a bunch of keys, it is vulnerable whether those keys are deleted or not.
    • evgen 11y ago
      If the key hash did not have facebook as the first eight characters it did not even get passed up to the aggregator and was instantly discarded.
• danielvf 11y ago
  Onion names are sort of public keys. You generate a secret key, then that's transformed/hashed into the public key that is your onion address. Since onion addresses are essentially random strings of a certain length, the only way to get a "vanity" onion address is to brute force it.
  • 0x0 11y ago
    Also, if I'm not mistaken, this means that if YOU can brute force a vanity domain, anyone else willing to throw down the same amount of computing power can perform the same brute force and discover your private key, taking over your onion site? Edit: probably wrong, see below
    • eterm 11y ago
      Normally you brute force vanity addresses by having a range of acceptable outcomes, whereas to brute force a specific vanity address* you are only targetting a single outcome. So they might have just set it to filter for facebook[dictionaryword]+ and this was the best match. * Actually any address, it's not limited to brute forcing vanity addresses.
      • 0x0 11y ago
        I guess I incorrectly assumed the process would be repeatable, but now I see that getting a specific duplicate equals bruteforcing the entire key space - even if the prefix is a chosen vanity name. I confused it with the effort of getting a similar address where just the vanity prefix needs to match.
    • nocarrier 11y ago
      It requires substantially more compute power to match "facebookcorewwwi" vs just finding a hash with a prefix of "facebook" that looks readable. Good luck hashing the remaining eight characters!
      • Russell91 11y ago
• loeg 11y ago
  Onion domains are just an encoding of a hash of a public key. To get a memorable name, you have to find a keypair that hashes to some letters you want. There is no correlation between any of the characters, so you have to do an exhaustive search to find nice strings.
• 0xdeadbeefbabe 11y ago
  Because it happened in the past with a hashing algorithm that isn't resistant to getting faster as time progresses.