CHAP password using perl

Hi all, I wrote a code in perl to calculate remaining time using my own database. for authentication I used User-Password attribute. but then I tested it with real NAS server and I realized that I haven't catered CHAP password. Now I want to ask that if there any module which convert CHAP password to user-password feild or there is any way to integrate CHAP password module in perl code. Means I want to authenticate CHAP password through my own perl code, how will I do it. I'll be thankful for any help Regards, Saeed Akhtar