Do you put a private key or public key in the input.txt because I used 1 public key. When I ran the script it gave me just 1 public key.
Oh you just use public keys.
Just change the
nkeys variable at the top to be the number of keys you want to receive (and make sure
bits_toinspect is greater than or equal to log2(nkeys).)
That's equivalent to knowing the very lowest bit of the private key so you've effectively reduced your search range by a power of 2 e.g. 2^60 --- 2^59. It's not useful enough in a practical setting though. Not to mention there isn't a foolproof way to guess the private key's parity in the first place.
Do you have an example of that?
Example of which one? You are quoting two different problems here. The latter one is "how to guess the lowest bit of all PKs with 100% confidence" which is impossible to do.