Variable mask in the middle of the password

[pkern]

I have a relatively long string (36 characters plus) that is of the form prefix<password>suffix, where prefix and suffix are completely static. I wanted to use a mask in the middle but I can't seem to figure out from the various documentation if that's actually possible, if I need the mask generator or if there's a smarter way. The best approach for me would be to be able to throw in a dictionary for the middle value first for the easy cases and then do with the mask-based brute force approach. I suppose I can write a rule that does prepend and append at the same time and that's easy. But I can't figure out how to combine that with masks and/or increments. I suppose if I need to implement the incrementing manually on each step that'd be fine though.

Any pointers are appreciated, happy to dig further myself once I know what the right track could be. Thanks!