*ahem*

@n=('_','a'..'z','.');

you could also trim one off by changing $#n to 27

Other than that your code is indeciperable to me
;-)

update :
also consider what happens when you shuffle the ciphertexts to

3 b_ylxmhzjsys.virpbkr
5 cs.
101 thqqxw.lui.qswer
[download]

You get

beware._dogs_barking
catare._dogs_barking
this_is_a_secretking
[download]

!!