> hashes each set of 6 digits
nice, now i can dictionary attack any key, 6 digits at a time
I don't think that's how it works... It's a checksum, not letting you check if each section is part of the key.
At worst, the key would have some portion less entropy since there's a lot of bits used for checksums.
Another VERY nice feature is it hashes each set of 6 digits as you type, so if you transpose one, you immediately get feedback instead of "invalid key!" after typing the whole thing out.