9 ms·

> Bear in mind, these companies know which ads they've shown you and when, for example, and at least in one case, buys your credit card transaction history to c

> Bear in mind, these companies know which ads they've shown you and when, for example, and at least in one case, buys your credit card transaction history to compare your purchases with the ads you've seen. Correct me if I am wrong but are you saying one of these two companies buys people's credit card transaction history and then compares people's ad history against the transaction history? If yes, that sounds really incredible.

ocdtrekkie 9y ago
Straight from the horse's mouth: https://adwords.googleblog.com/2017/05/powering-ads-and-analytics-innovations.html https://adwords.googleblog.com/2017/05/powering-ads-and-anal... "And even if your business doesn’t have a large loyalty program, you can still measure store sales by taking advantage of Google’s third-party partnerships, which capture approximately 70% of credit and debit card transactions in the United States."
- cromwellian 9y ago
  IIRC, this was announced as part of a program that uses double-blinded crypto that allows google to perform matching against this data in aggregate (Set intersection knowledge), but not individually identity of what a given user purchased, at the same time preventing the merchants from learning the identities of individuals either. According to what they presented at a crypto conference, they went to great pains to avoid capturing personally identifiable transactions. The overall strategy is that Google Knows = Set A = (all ads shown for user X at Merchant Y) Merchant/Credit Card Proccessor Knows = Set B = (all $$$ paid by User X at Merchant Y), and that it is possible to cryptographically compute sum($$$ of A intersect B) without either side learning Set(User X). Now whether you believe in the security of the algorithm and whether there are side channel leaks or attacks is another issue. Edit: http://bristolcrypto.blogspot.com/2017/01/rwc-2017-secure-mpc-at-google.html http://bristolcrypto.blogspot.com/2017/01/rwc-2017-secure-mp... About 10 minutes in https://www.youtube.com/watch?v=ee7oRsDnNNc https://www.youtube.com/watch?v=ee7oRsDnNNc
908087 9y ago
Yes, both Google and Facebook do exactly that.
kerng 9y ago
Yes, this was in the news a few times.

ocdtrekkie 9y ago

Straight from the horse's mouth: https://adwords.googleblog.com/2017/05/powering-ads-and-analytics-innovations.html https://adwords.googleblog.com/2017/05/powering-ads-and-anal... "And even if your business doesn’t have a large loyalty program, you can still measure store sales by taking advantage of Google’s third-party partnerships, which capture approximately 70% of credit and debit card transactions in the United States."

cromwellian 9y ago
IIRC, this was announced as part of a program that uses double-blinded crypto that allows google to perform matching against this data in aggregate (Set intersection knowledge), but not individually identity of what a given user purchased, at the same time preventing the merchants from learning the identities of individuals either. According to what they presented at a crypto conference, they went to great pains to avoid capturing personally identifiable transactions. The overall strategy is that Google Knows = Set A = (all ads shown for user X at Merchant Y) Merchant/Credit Card Proccessor Knows = Set B = (all $$$ paid by User X at Merchant Y), and that it is possible to cryptographically compute sum($$$ of A intersect B) without either side learning Set(User X). Now whether you believe in the security of the algorithm and whether there are side channel leaks or attacks is another issue. Edit: http://bristolcrypto.blogspot.com/2017/01/rwc-2017-secure-mpc-at-google.html http://bristolcrypto.blogspot.com/2017/01/rwc-2017-secure-mp... About 10 minutes in https://www.youtube.com/watch?v=ee7oRsDnNNc https://www.youtube.com/watch?v=ee7oRsDnNNc

908087 9y ago

Yes, both Google and Facebook do exactly that.

kerng 9y ago

Yes, this was in the news a few times.