A friend of mine decided to encrypt his Private Key with a BIP38 protocol. And now he does not remember the Password. 18BTCs is the Amount of Bitcoins in that Wallet that is encrypted.
Any idea to decrypt that private key?
Unfortunately, BIP38 is quite "secure"... unless he has a fairly good idea of what the passphrase used was and used a relatively simple password... bruteforcing is going to be a sloooooow process (like years and years). Not sure of any really reliable BIP38 brute forcing tools... but a quick search found this:
https://github.com/countzero/brute_force_bip38 and this
https://github.com/cculianu/brute38/
There are some programs around that could do it, if he remembers his seed and have at least an ideia about what the passphrase could be
Not applicable... OP is talking about BIP38 encrypted private keys (eg. an encrypted paper wallet)... not a BIP39 wallet with a passphrase.