Bitcoin Forum

Let's just say, hypothetically, that there was an abandoned wallet with, like, $150,000,000 worth of BTC in it.  Say, one of Sheep's.

• How long would it take to find the private key and gain access to the coins?  For one machine, or for a pool?
• If everyone got together and formed a pool, and split the payout, would it be worth the energy costs?
• Is there a difference between the difficulty for SHA256 and Scrypt with regards to wallet private keys?
• Are there any cryptocoins that are particularly susceptible to wallet private key attacks?

If it were possible to crack a private key, then Bitcoin wouldn't be very secure. It is far more lucrative to mine bitcoins than it is to try to find a private key, even the private key of one of those addresses with 500,000 bitcoins.

A wallet is a collection of Bitcoin addresses and it contains the private keys (unless it is a watch-only wallet).  People normally encrypt the wallet file to protect it.  If you had a copy of that wallet file you could try to break the encryption.  That depends on the type of encryption, length of password, etc.  there are services that crack these wallets and I assume they use tools like John the Ripper.

If you see a Bitcoin address on the blockchain and you try to find the private key randomly most likely the sun will burn out before you find it.

I can't make heads or tails of the part about the mining difficulty of different proof of work algorithms.  ASIC miners can only do hashes, they can't generate Bitcoin addresses if that is what you mean:
https://en.bitcoin.it/wiki/Technical_background_of_version_1_Bitcoin_addresses

You wouldn't want to, cause if you did, bitcoin would crash teh very next day   8)