I'm selectively enabling CA trusts on my Android phone by disabling all Trusted CA's and then enabling only ones that I need to run on a daily basis. To re-enable WhatsApp attachments (I couldn't download photos anymore) I had to enable ValiCert, Inc. (http://www.valicert.com/). There's three of them listed, but I only needed to enable the first one.
This was a little troublesome because when I went to https://whatsapp.com in by browser, they're using a certificate published by DigiCert...which did not help when I re-enabled it.
Photos are downloading again!
