You may need a script to generate the latter. (can anyone provide the numbers if the latter if possible?)
Let's see.
You can generate a 12 word seed phrase with a valid checksum and use that as the first 132 bits of entropy for your 24 word seed phrase. Concatenate another 124 bits of entropy, and then calculate the 8 bit checksum to give yourself a valid 24 word seed phrase. Take the last 12 words of this seed phrase. Given 12 words have a 4 bit checksum, then there is a 1/16 chance that this checksum is valid. So it won't take long at all to bruteforce a valid combination.
Here's one I just made in just a few minutes:
pupil magic fun throw lecture sunset pizza fashion helmet couch auto impact despair height humor impose near plunge clever abstract swing laundry scheme acquire
Nice, thanks for sparing the time.
So it's faster than I anticipated, I was thinking of generating the 24-words from a 256-bit entropy in one go.
Pre-generating the valid first half and filling the rest is one nice trick to minimize the search space for a valid whole (
24-words) and last half (
12-word) checksum.