<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto">Hi,<div><br></div><div>V2 onions are a truncated SHA1. Doing an entire hash is expensive.</div><div><br></div><div>V3 onions are an ed25519 key plus a suffix. So if you're just looking</div><div>for a prefix, you can choose a random value. Then increment by the</div><div>basepoint until you find the prefix you want. (This is a relatively</div><div>cheap operation, because you're just adding 255-bit numbers.)</div><div><br></div><div>You can save the expensive suffix calculations for the final</div><div>candidate keys.</div><div><br></div><div>Here's one implementation:</div><div><a href="https://github.com/Yawning/horse25519/blob/master/src/horse25519.c#L209">https://github.com/Yawning/horse25519/blob/master/src/horse25519.c#L209</a> </div><div><br></div><div>This is a summary: there are a few important details to get right,</div><div>like key masking and security.</div><div><br><div dir="ltr"><span style="background-color: rgba(255, 255, 255, 0);">T</span><div><span style="background-color: rgba(255, 255, 255, 0);"><br></span></div><div><span style="background-color: rgba(255, 255, 255, 0);">-- </span></div><div><span style="background-color: rgba(255, 255, 255, 0);">teor</span></div><div><span style="background-color: rgba(255, 255, 255, 0);">----------------------------------------------------------------------</span></div><div><span style="background-color: rgba(255, 255, 255, 0);"><br></span></div></div><div dir="ltr"><br><blockquote type="cite">On 27 Apr 2020, at 06:37, niftybunny <abuse-contact@to-surf-and-protect.net> wrote:<br><br></blockquote></div><blockquote type="cite"><div dir="ltr"><span>Hi there,</span><br><span></span><br><span>quick question. Is there a fundamental time difference between brute forcing V3 to V2 Onion domains or did my 4 lucky feet just stopped working?</span><br><span></span><br><span>niftybunny</span><br><span></span><br><span></span><br><span>_______________________________________________</span><br><span>tor-onions mailing list</span><br><span>tor-onions@lists.torproject.org</span><br><span>https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-onions</span><br></div></blockquote></div></body></html>