shallot

according to [1], about a day for the 7 character twitter url on a 1.5GHz machine. So nothing really for a company like twitter. [1] https://github.com/katmagic/Shallot

It must've been brute-forced. According to this one old brute forcer I found [1] but have not thoroughly vetted, it would've been one CPU-day of effort on 2012-era hardware [1] https://github.com/katmagic/Shallot

I used https://github.com/katmagic/Shallot back then and it took 35221958203 attempts to find one with my chosen seven characters. For the longer v3 .onions you'll want a different tool, this page mentions some and makes some estimates for finding increasing lengths of characters: https://www.jamieweb.net/blog/onionv3-vanity-address/

Facebook's hidden service address is particularly impressive: https://facebookcorewwwi.onion/ It seems like everything except the 'i' is a prefix, a lot of computing must have went in to generating it. One tool to do it is called 'Shallot' https://github.com/katmagic/Shallot The readme includes a table of estimated computing time required. A 15 char prefix like Facebook's is not even on the table, and a 14 char prefix is estimated to take 2.6 million years. There is also a GPU version which should be an order of magnitude faster: https://github.com/lachesis/scallion/blob/gpg/README.md Also, technically. the onion addresses not public keys, but derived from a public key. It's actually a hash of the public key. It appears that the hashing algorithm used is SHA1. Source: The last few lines of the easygen function https://github.com/katmagic/

I'm guessing they used something like scallion [0] or Shallot [1]. Bench marking Shallot on an Intel 3350P@3.10GHz: time ./shallot ^a -> 0.09 sec user time ./shallot ^aa -> 0.12 sec user time ./shallot ^aaa -> 0.12 sec user time ./shallot ^aaaa -> 0.47 sec user time ./shallot ^aaaaa -> 5.92 sec user time ./shallot ^aaaaaa -> 118 sec user Unfortunately OpenCL doesn't work with the nouveau drivers so I can't test scallion. Who knows how much they spent trying to brute force that onion address. EDIT: Ok looks like they went the backronym route [0] https://github.com/lachesis/scallion [1] https://github.com/katmagic/Shallot

There are a few different programs that will do it, but it comes down to brute force, so the difficulty depends on the length. https://github.com/katmagic/Shallot https://github.com/lachesis/scallion

How long must they have let scallion/Shallot. https://github.com/katmagic/Shallot is quoting a 10char prefix on the order of decades for a single machine.

Good point. At some point, you'll need to communicate the onion address over a trusted channel. If you trust SSL, then you can serve the landing page over HTTPS, or as others have suggested, you could print the address in the New Yorker itself. I have also heard of using Namecoin or other proof of work schemes, although that would be outside the reach of the average user. If neither of these avenues satisfy, a simple idea for defense-in-depth I've thought of is using .onion vanity name generators (see https://github.com/katmagic/Shallot) as a very simple proof of work scheme. For example, silk road's .onion starts with silkroad. Finding such an .onion address for a given private key requires brute force computation - according to the Shallot github, about 25 days. Therefore, generating an .onion with a recognizable string at the beginning

If they wanted to make a memorable address, they would have to run something like Shallot [1]. This is essentially brute forcing private keys until you find the public key you want. Depending on the name, that could take a very long time. [1] https://github.com/katmagic/Shallot