Hi, I'm the right person for the job, I have the developer skills to change the cipher method from md5 to sha256 just the PDF file explains.
I will be quick, clean and safe with your code as a Bank requires top security in it's services.
I will back up the files before I modify them, so I will be ready for a backroll if you require it.
You will get a report of the files and lines modified.
Don't waste your time and feel free to contact me any time.