use strict;
use warnings;

my $test_crypt = "NK JNK YJ YAK ZPCCTK GDKQ YAK YNJ NJVQY PUSKUYPJUQ JR AMZGUPYL - VJZGUYPX TJSK GUC DMUOJNCKV. -- GUCVK ZGMVJPQ";
my $key        = 'something';
my $word       = 'PUSKUYPJUQ';

eval "\$test_crypt =~ tr/$key/$word/";