[_ck_]

okay I found the cause but not the reason or solution.

this produces entirely different results in WP trunk vs BB trunk:

echo wp_hash("abc". "123")." - ". hash_hmac('md5', "abc" . "123", wp_hash("abc". "123"));

So each program cannot evaluate the other’s hash/key/hmac

Still researching. The salt is identical. This is perplexing.