js

 var keys = new Object();
        keys.a = 'abcdefghijklmnopqrstuvwxyz';
        keys.b = 'bcdefghijklmnopqrstuvwxyza';
        keys.c = 'cdefghijklmnopqrstuvwxyzab';
        
  
  var key = 'aab';
  var text = 'abc';