Your imagination required: How to encrypt a file so that spending an amount of bitcoins is required for the decryption

Question

Bitcoins are an anonymous encrypted digital currency. I got the idea a few months ago to encrypt a file where a spending proof of bitcoins would be required to decrypt the file. When a bitcoin is sent to a given address, it shows back in the block file distributed in the peer-to-peer network. The integrity of the block chain is secured by requiring a large number of computers to perform complex calculation. The proof of this calculation serves as the signature.

Do you think there is a way to encrypt a file in such a way that, the only way to decrypt it would be to supply:

1. A valid bitcoin block code
2. This block code has a non-zero amount of bitcoin that was spent to an bitcoin address.
3. This bitcoin address is unique to the file we wish to decrypt.

The result would be that anyone trying to brute force the file would go financially broke very quickly. Whereas the genuine user would only have to spend a penny to decrypt it.