[RichieAHB]

Interesting. That probably does makes it a bit harder to verify but there are still plenty of “words” that are to be expected. My point being that if a German receiver can’t parse it, then what’s the point of send it. And if they can parse it we can encode the rules they’re using to parse it (i.e. at the very least a dictionary of “words”) to give us some decent confidence. And beyond that, using the key on multiple messages effectively increases the char limit to “max chars * message count”.

Also, I agree it doesn’t reduce the search space but I think the post I was replying to was talking more about difficulty of verifying the correctness of a decrypt that reducing the search space. That was definitely my point ant least. Either way, as you say, this definitely doesn’t reduce the search space.