Post
Topic
Board Bitcoin Discussion
Re: Bitcoin scripting puzzle from the MIT Expo
by
halftimepad
on 18/07/2015, 19:16:38 UTC

I don't think you can spend the second output of the transaction. The script is:

OP_HASH256 OP_HASH256 0 ffffffffffffffffffffffffffffffffffffffffffff OP_WITHIN

It seems the sender wanted a problem similar to mining: find a string with a low hash and get the reward.

But OP_WITHIN and all the arithmetic operators only work for inputs of up to 4 bytes. Quoting from
https://en.bitcoin.it/wiki/Script#Arithmetic
"If any input value for any of these commands is longer than 4 bytes, the script must abort and fail."

ffffffffffffffffffffffffffffffffffffffffffff has 22 bytes. OP_WITHIN will cause the script to fail, no matter what inputs you choose. These bitcoins are irredeemable.