Your uncle really used the MiniKey standard? So 30 characters in base58 only, with 00-check?
You seem surprised - why?
Yes, it's a minikey, but in fact it's base 32: numbers and caps only. (This was explained in the first episode.)
This still makes it way to hard to brute force (145 bits of entropy - the original Casascius coins had 123) but easier to remember and less confusion about whether any given clue is upper or lower case.
A minikey is base58 and has the 00-check. Base58 means for example that no zero is allowed in the key.
Base32 is all capital letters, and the numbers 2 till 7. By mentioning base32 I am now even more confused.
Edit: is the 00-?-check still in place?
It's a totally standard minikey, so yes the 00 check is still in place. The only difference is that the characterset has been reduced:
BASE32 = '23456789ABCDEFGHJKLMNPQRSTUVWXYZ'
BASE58 = '23456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz'
So it's a base 32, not the 'standard' base 32 (which I understand isn't used that much). Sorry for the ambiguity.
If you want to see the code used to generate the minikey, take a look at
https://en.bitcoin.it/wiki/Mini_private_key_format#Python_CodeAside from using a reduced characterset, the only major difference is that I used a better source of entropy than random.
I've used all caps and numbers simply because I didn't want people to have to wonder whether a clue was upper or lower case.
Hope that helps!
I must say this puzzle is really hard ...
