OK first at SourceForge on this page:
to the right of each file there is a gray circle with an i. That has checksums.
My understanding is that checksums should have been published with both torrents and on mirrors (haven’t checked mirrors yet myself). So an unfortunate oversight. At any rate the checksums are here:
x86_64
https://abf.openmandriva.org/platforms/3.0/products/38/product_build_lists/507
i586
https://abf.openmandriva.org/platforms/3.0/products/41/product_build_lists/508
I have checked my .iso files downloaded via KTorrent and here checksums match. I’ll do my best to inform our Infrastructure Team about getting them properly published.