Appendix C: Recommendations for searching for vanity .onions [VANITY]

EDITORIAL NOTE: The author thinks that it's silly to brute-force the keyspace for a key that, when base-32 encoded, spells out the name of your website. It also feels a bit dangerous to me. If you train your users to connect to


I worry that you're making it easier for somebody to trick them into connecting to


Nevertheless, people are probably going to try to do this, so here's a decent algorithm to use.

To search for a public key with some criterion X:

Generate a random (sk,pk) pair.

While pk does not satisfy X:

            Add the number 8 to sk
            Add the point 8*B to pk

        Return sk, pk.

We add 8 and 8*B, rather than 1 and B, so that sk is always a valid Curve25519 private key, with the lowest 3 bits equal to 0.

This algorithm is safe [source: djb, personal communication] [TODO: Make sure I understood correctly!] so long as only the final (sk,pk) pair is used, and all previous values are discarded.

To parallelize this algorithm, start with an independent (sk,pk) pair generated for each independent thread, and let each search proceed independently.

See [VANITY-REFS] for a reference implementation of this vanity .onion search scheme.