https://news.ycombinator.com/item?id=26570795
https://news.ycombinator.com/item?id=25397787
https://news.ycombinator.com/item?id=25390941
https://news.ycombinator.com/item?id=25387216
There are more submissions, some have several comments ... you can find them here:
https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...
Worth noting that hard/impossible to crack doesn't automatically mean a cipher is good. One can easily scramble letters in ways that makes it literally impossible to decipher, but that defeats the whole point.