how to use chasepaymentech encryption in javascript

I'm doing dynamically-generated PIE settings for the payment with chasepaymentech

trying to get this 9fbc3c3a1bd26c46 from 70E99B247C0E6B77679F65F1D721B120

i will use 9fbc3c3a1bd26c46 as integrityCheck this is the hole things

PIE.L = 6;
PIE.E = 4;
PIE.K = "70E99B247C0E6B77679F65F1D721B120";
PIE.key_id = "2595de71";
PIE.phase = 0;

this pie.k will be 
9fbc3c3a1bd26c46

it use this js for encryption