>>Where can I get source code that would let me encrypt in AES-256 in VFP9?

Craig Boyd's vfpencryption.fll includes lots of ciphers including AES256 that is the default:

lcAES256=Encrypt(m.lcString,m.lcPassword)
lcOriginal=Decrypt(m.lcAES256,m.lcPassword)

Free download and documentation used to be available at Craig's sweetpotatosoftware.com site but that domain appears to have expired in July 2021. If anybody knows Craig, maybe see whether he wants to keep the domain that I believe can be resuscitated for a year... meanwhile I see there are other download repositories via search, plus documentation like this: https://doughennig.com/Papers/Pub/201103dhen.pdf . If you can't find the fll, I have it and so do many others here I'm sure. The other issue is the runtime libraries needed by various versions of Craig's flls; some of the MS support libraries no longer come with Windows by default. I don't, but if anybody has a copy of Craig's documentation, that could save hours of "fun".

FWIW If you use VFP Compiler, you can embed AES256 inside your app dll meaning no extra fll or other dependencies to worry about..