Simple string interleaving. The resultant string will be as long as the shortest stringx2 and as an added bonus the penultimate character of the first string is appended to the end. All in raw JavaScript.

StringInterleaving.js

var string1 = 'ARNFH-U-5728';
var string2 = 'SO06DNV';

var array1 = string1.split('');
var array2 = string2.split('').reverse();

var obfuscated = '';

array1.every(function(e, i, a) {
   if (typeof array2[i] === 'undefined') {
        obfuscated += array1[(array1.length - 1)]; 
        return false;
   }
   obfuscated += e + array2[i];
   return true;
});

//console.log(obfuscated);