[dutchbrit]

Directory.io first of all does not contain all private keys - it's more of a joke.

Anyway, if a brain wallet has a weak password, you have quite a good chance of cracking it easily. But you have to know that it's a brain wallet. But using a brain wallet is just silly.

Also, don't forget cracking private keys using weak signatures, although good luck finding someone who has a wallet and a weak signature...

http://www.nilsschneider.net/2013/01/28/recovering-bitcoin-p...

EDITED - I didn't read the post correctly, my apologies.

[enscr]

Can't vouch for what's on directory.io but it goes as far as http://directory.io/9046256971665327767466483203803742801002... & beyond... have you tried paging through?

https://en.bitcoin.it/wiki/Private_key

"In Bitcoin, a private key is a 256-bit number, which can be represented one of several ways. Here is a private key in hexadecimal..."

Edit : The bitcoin private key being a number was in response to your redacted comment.

[palkeo]

Of course directory.io is a joke :)

A private key IS a number : https://en.bitcoin.it/wiki/Private_key The one you shown was just encoded in base58 !

[LyndsySimon]

To be really precise, it's encoded base58check.