Online payment system / encryption change - expert!

We have one EU company payment system for the Laravel booking website. They changed the type of encryption and we need an expert who can change it from the MD5 encryption to the SHA512. We will send you all files that are modified for the payment system (5 files) and the payment system manual that is in the English version. It's not large task but needs to be created properly and asap. Only developers who build and created integration of the custom made payment gateways