Assume that I have a product that is really good at maintaining loyalty and subscriptions for a site, and that it targets its customers that leave it, and is able to bring them back! But for me to do so, I need customer email addresses, age, gender, etc. Emails are mostly used for retargeting in sites such as FB, Instagram, etc.
Now assume that I offer this product to a dating site, or even better, some sort of banking or lending site. Both the dating site and the banking site will be uneasy to share with me their customer data that I need to plug into my algorithm - for obvious reasons.
Can anybody think of a way in which such sites can provide this data to me, WITHOUT compromising their security? I am NOT interested in their customer data, but I do need it to plug it into my system so as to retain their customers.
In short, imagine yourself as the owner of a well-known dating site, and you wish to use my algorithm, but you don't want me to see your customer information or have a rogue employee divulge it elsewhere.