I liked the starting principle here...but then it got a bit silly and golfy :) Not hard to understand, but takes a little to untangle.

$japh='AJPJAjajHAJPHAJaaJPAjJajAJaaJPAJHJAjJAjaJHPAJhaAJAJPJAJaaJPAjJA
+JpaaaJHaAJ';
$japh=~s/$_/uc($_ x2)/eg for(split(//,'japh'));
print join(' ',reverse map{ucfirst lc}split('@',join('',map{split(//);
chr(eval join'+',map{index('JAPH',shift(@_))<<($_*2)}map{index('JAPH',
+$_)}reverse split(//,'JAPH'))}$japh=~m!(....)!g)));
[download]

Enjoy. Ben.