Ben Kreuter RWC 2017
Why Hacker News recommends it
Cited in threads about Google's purchase tracking as the technical source for how the matching might work.
What it is
A Real World Crypto 2017 talk by a Google engineer on using private set intersection to match ad views with in-store purchases. It describes privacy-preserving matching that avoids exposing personal transactions.
Recommended by 0 HN commenters across 0 different months, 2017 to 2018.
What Hacker News said
Cites russell_h · 2017-05 · on “Google starts tracking what people buy in physical stores”
A Googler gave a talk at Real World Crypto in January describing a system that might back this. The relevant part of the talk starts around the 10 minute mark: [this video] In short, they're able to compute the intersection of the set of users who have viewed an ad with the set of people who purchased a product in a store, without either party disclosing their side of the set.
Cites cromwellian · 2017-07 · on “Google’s new program to track shoppers sparks a federal privacy complaint”
It's actually not given to Google in a user identifiable way. I am not privy to the details, but an overview was presented at a crypto conference: [this video] It looks to me like a form of homomorphic encryption where both the aggregate consumer transactions (people bought X at merchant M), and the aggregate Google ad information (people saw ad for X at merchant M) are encrypted and the set intersection is computed on the ciphertext revealing only the aggregate number of purchases, not the individuals. Now granted, there could be a security hole in this scheme as with any crypto-protocol, so it does need peer review, but the design, as stated in that YouTube presentation, is not to reveal to Goo
Cites cromwellian · 2018-03 · on “Are you ready? This is all the data Facebook and Google have on you”
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 c
Cites vatueil · 2018-03 · on “Are you ready? This is all the data Facebook and Google have on you”
> Google buys your credit card purchase data. A more accurate explanation of the scare quote: [LINK] > 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 Proccess