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Unfortunately, credit card companies/banks/etc have been selling purchasing histories, to pretty much all comers, for years. It'd be really nice if we could st

Unfortunately, credit card companies/banks/etc have been selling purchasing histories, to pretty much all comers, for years. It'd be really nice if we could stop that instead of caring about the particular people they sell it to. IE It's not "better" when they sell it to someone who isn't Google, and I honestly could't give a crap about the complaint, which mostly deals with antitrust.

ocdtrekkie 9y ago
Yeah, first and foremost, it bothers me that this data can be sold at all in a user-identifiable way. (Presumably for Google to be able to link it to accounts, name and address are included in the data.) Perhaps this offers the opportunity for a product, in the short term: Is anyone offering credit cards which promise not to sell your purchase history? I'd be game for that.
- cromwellian 9y ago
  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: https://www.youtube.com/watch?v=ee7oRsDnNNc&t=10m1s https://www.youtube.com/watch?v=ee7oRsDnNNc&t=10m1s 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 Google personal purchasing information, nor reveal to merchants, personal profile information. No personal financial data or purchasing information is supposedly transmitted. The problem with this kind of technology is that it is really difficult to explain to the public, and easily demagogued.
  - ocdtrekkie 9y ago
    My question is... how is that supposed to work? How do they turn "person A's credit card account" and "person A's Google account" into something comparable. To say "X customers saw the ad and then purchased it", you've gotta be able to be able to confirm that the same person is on both sides of the dataset, which is a pretty hard problem even without it allegedly not sharing the info on one side with Google. I guess this complaint from this article is asking the FTC to get more information on this process, or get Google to explain how it works, or something. Upvote for the explanation.
    - sloppycee 9y ago
      You can use geography, I assume this is meant to measure ROAS. I've worked on a similar problem, and some very large retailers we worked with wanted to measure ROAS. They turned off all adspend in a certain large metropolitan area, while we turned on in that area. Measuring the sales lift/drop, gave an idea of the platform's effectiveness. Any other demographic data point could also be used, not just geo. You don't necessarily need to link people directly.
    - UncleMeat 9y ago
      Homomorphic encryption to do set intersection. With sufficiently large sets, you don't need to do any sort of collection at the individual level.
    - singron 9y ago
      I don't know in this case, but there are several identifiers that both parties might have (phone number, email address, billing address, name). In the industry, you can sometimes get "anonymized" data that is keyed by a hash of these identifiers, then you can hash your own identifiers and join to deanonymize. This isn't how it works in this case, but I know other companies do this.
  - hedora 9y ago
    Assuming the encryption works as advertised, these schemes still allow more de-anonymization than you'd think. If you can compute very specific set intersections you can then get the set size low enough to reveal personal information with 100% certainty. (The set of people that bought X at M and Y at N and saw ad A at P and ad B at Q on a particular day might contain one person) I do not know of any work in homomorphic encryption that claims to provide privacy guarantees in the face of side-channels from other sources (in this case, the side-channels could be phone location information for brick-and-mortar purchases, or web browsing activity timestamps for online purchases). It's not surprising that such work is hard to find, since merely computing correct query results breaks most reasonably privacy guarantees. Also, the field of homomorphic encryption encourages people to use horrible cipher-modes like code-book, so guilt-by-association makes me highly suspicious of stuff in that space: https://en.m.wikipedia.org/wiki/Block_cipher_mode_of_operation#Electronic_Codebook_.28ECB.29 https://en.m.wikipedia.org/wiki/Block_cipher_mode_of_operati... The closest thing I know of that is workable is differential privacy, which (in laymans terms) introduces enough noise to make sure that overly-specific queries return random (but representative) garbage. Apple says they use differential privacy to train models on data that's stored on iPhones without actually giving themselves access to that data. Cool stuff.
trendia 9y ago
Visa is working to prevent people from using cash in stores [0]. Currently, they are merely giving merchants an incentive to change, but in the future they may use their immense lobbying power to get preferential legislation enacted. Once cash is gone: 1. your purchases will be available to any company willing to pay for it, and 2. Visa will get a de facto "tax" on all transactions (through 1-2% merchant fees) [0] https://www.wsj.com/articles/visa-takes-war-on-cash-to-restaurants-1499853601 https://www.wsj.com/articles/visa-takes-war-on-cash-to-resta...
- Theodores 9y ago
  So how do we fix this? In the days when we had interest rates it was possible to make money on transactions by taking the money one day and paying the invoice on the next day. Overnight the money would earn interest. This would be profit to cover the transaction. So a bank could make money moving cheques around for people, taking two weeks to clear back in the days when everything was manual. So with electronic payment there is no human inspecting signatures and doing data entry. So why the merchant fees? In a free market a competitor that just makes money on interest should be winning here.
  - cbhl 9y ago
    AFAICT, interest rates are too low (near zero) for banks to make a profit on interest margins alone. You could have a non-profit do the interchange, like the Interac network in Canada, but that would be difficult to coordinate without consolidating all the banks. (Canada has, like, only half a dozen.)
    - Theodores 9y ago
      Actually this is solved in the eurozone with that payment method, name forgotten... It is a fundamental bit of what the Euro is about being able to transfer money without the fees.
      - k-mcgrady 9y ago
belltaco 9y ago
It would be nice if commenters like you added a disclaimer that you work for Google in comments that hand wave away Google's privacy issues.
- ocdtrekkie 9y ago
  Eventually you just get the gist for who around here works at Google. ;) cromwellian, who responded to one of my comments here, is also a Googler. Arguably, DannyBee is correct that the real issue is that credit card companies are allowed to sell this data at all. But perhaps the danger of this practice is especially highlighted by the fact that Google is now one of the buyers.
  - stephengillie 9y ago
    Should HN have an employer field next to user names, like the domain field next to the article name? It may have helped with the recent Docker issue.
    - ocdtrekkie 9y ago
      I don't think there's a lot of benefit to this. People would still debate whether or not they needed to disclose. Some people believe that if their posts are their personal views, they don't need to disclose. People might be more likely to use throwaway accounts for personal opinions or posts on unrelated topics. Since HN doesn't mandate any of this be provided (or accurate), it becomes useless. I usually don't disclose my employer on my profile... but I don't work at a startup or major tech company and no companies discussed here have any sort of relationship with mine. I think people should disclose they work for a company they are defending the position of online. But I don't see a way to force that issue in an environment that permits anon accounts.
      - DannyBee 9y ago
        I dunno, either people are there companies or they aren't. I am not my company, and a lot of people elsewhere aren't either. I don't think who we work for is really relevant at all unless they are trying to make offical statements. Either engage on the merits or don't. "Ignore this guy, he works for X" is not a useful line of argumentation. The only thing putting company names next to things would create, IMHO, is an echo chamber. (This is very different than journalists being paid to write specific articles or funded to do specific research, or even people paid quite specifically to astroturf) If we believe it's some magical generalized conflict of interest, why stop at company names. In any article about NIMBYism, should we require people post whjether they rent/own/own a home > 2 million/whatever. etc IMHO it's completely irrelevant to the merits of their argument. The merits don't change one way or the other. It seems the only usefulness would be able to filter/confirm biases. At that point, why bother having a discussion.
k-mcgrady 9y ago
>> IE It's not "better" when they sell it to someone who isn't Google It's better in the sense that those companies can probably do much less with purchase histories than Google as they have less total information on me (whereas Google has email, web history, photos, etc. if I allow them).
Paul-ish 9y ago
> Unfortunately, credit card companies/banks/etc have been selling purchasing histories, to pretty much all comers, for years. Do you have evidence of this?
- hellbanner 9y ago
  https://www.theguardian.com/money/2013/jun/08/supermarkets-get-your-data https://www.theguardian.com/money/2013/jun/08/supermarkets-g... https://www.forbes.com/forbes/welcome/?toURL=https://www.forbes.com/sites/moneybuilder/2013/04/29/this-week-in-credit-card-news-collecting-your-personal-data-why-you-should-pay-by-credit/ https://www.forbes.com/forbes/welcome/?toURL=https://www.for... http://www.thesimpledollar.com/how-credit-card-companies-make-money/ http://www.thesimpledollar.com/how-credit-card-companies-mak... https://www.creditfirm.net/blogs/mastercard-to-begin-selling-customer-data.html https://www.creditfirm.net/blogs/mastercard-to-begin-selling... http://www.businessinsider.com/credit-cards-sell-purchase-data-to-advertisers-2013-4 http://www.businessinsider.com/credit-cards-sell-purchase-da...

ocdtrekkie 9y ago

Yeah, first and foremost, it bothers me that this data can be sold at all in a user-identifiable way. (Presumably for Google to be able to link it to accounts, name and address are included in the data.) Perhaps this offers the opportunity for a product, in the short term: Is anyone offering credit cards which promise not to sell your purchase history? I'd be game for that.

cromwellian 9y ago
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: https://www.youtube.com/watch?v=ee7oRsDnNNc&t=10m1s https://www.youtube.com/watch?v=ee7oRsDnNNc&t=10m1s 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 Google personal purchasing information, nor reveal to merchants, personal profile information. No personal financial data or purchasing information is supposedly transmitted. The problem with this kind of technology is that it is really difficult to explain to the public, and easily demagogued.
- ocdtrekkie 9y ago
  My question is... how is that supposed to work? How do they turn "person A's credit card account" and "person A's Google account" into something comparable. To say "X customers saw the ad and then purchased it", you've gotta be able to be able to confirm that the same person is on both sides of the dataset, which is a pretty hard problem even without it allegedly not sharing the info on one side with Google. I guess this complaint from this article is asking the FTC to get more information on this process, or get Google to explain how it works, or something. Upvote for the explanation.
  - sloppycee 9y ago
    You can use geography, I assume this is meant to measure ROAS. I've worked on a similar problem, and some very large retailers we worked with wanted to measure ROAS. They turned off all adspend in a certain large metropolitan area, while we turned on in that area. Measuring the sales lift/drop, gave an idea of the platform's effectiveness. Any other demographic data point could also be used, not just geo. You don't necessarily need to link people directly.
  - UncleMeat 9y ago
    Homomorphic encryption to do set intersection. With sufficiently large sets, you don't need to do any sort of collection at the individual level.
  - singron 9y ago
    I don't know in this case, but there are several identifiers that both parties might have (phone number, email address, billing address, name). In the industry, you can sometimes get "anonymized" data that is keyed by a hash of these identifiers, then you can hash your own identifiers and join to deanonymize. This isn't how it works in this case, but I know other companies do this.
- hedora 9y ago
  Assuming the encryption works as advertised, these schemes still allow more de-anonymization than you'd think. If you can compute very specific set intersections you can then get the set size low enough to reveal personal information with 100% certainty. (The set of people that bought X at M and Y at N and saw ad A at P and ad B at Q on a particular day might contain one person) I do not know of any work in homomorphic encryption that claims to provide privacy guarantees in the face of side-channels from other sources (in this case, the side-channels could be phone location information for brick-and-mortar purchases, or web browsing activity timestamps for online purchases). It's not surprising that such work is hard to find, since merely computing correct query results breaks most reasonably privacy guarantees. Also, the field of homomorphic encryption encourages people to use horrible cipher-modes like code-book, so guilt-by-association makes me highly suspicious of stuff in that space: https://en.m.wikipedia.org/wiki/Block_cipher_mode_of_operation#Electronic_Codebook_.28ECB.29 https://en.m.wikipedia.org/wiki/Block_cipher_mode_of_operati... The closest thing I know of that is workable is differential privacy, which (in laymans terms) introduces enough noise to make sure that overly-specific queries return random (but representative) garbage. Apple says they use differential privacy to train models on data that's stored on iPhones without actually giving themselves access to that data. Cool stuff.

trendia 9y ago

Visa is working to prevent people from using cash in stores [0]. Currently, they are merely giving merchants an incentive to change, but in the future they may use their immense lobbying power to get preferential legislation enacted. Once cash is gone: 1. your purchases will be available to any company willing to pay for it, and 2. Visa will get a de facto "tax" on all transactions (through 1-2% merchant fees) [0] https://www.wsj.com/articles/visa-takes-war-on-cash-to-restaurants-1499853601 https://www.wsj.com/articles/visa-takes-war-on-cash-to-resta...

Theodores 9y ago
So how do we fix this? In the days when we had interest rates it was possible to make money on transactions by taking the money one day and paying the invoice on the next day. Overnight the money would earn interest. This would be profit to cover the transaction. So a bank could make money moving cheques around for people, taking two weeks to clear back in the days when everything was manual. So with electronic payment there is no human inspecting signatures and doing data entry. So why the merchant fees? In a free market a competitor that just makes money on interest should be winning here.
- cbhl 9y ago
  AFAICT, interest rates are too low (near zero) for banks to make a profit on interest margins alone. You could have a non-profit do the interchange, like the Interac network in Canada, but that would be difficult to coordinate without consolidating all the banks. (Canada has, like, only half a dozen.)
  - Theodores 9y ago
    Actually this is solved in the eurozone with that payment method, name forgotten... It is a fundamental bit of what the Euro is about being able to transfer money without the fees.
    - k-mcgrady 9y ago

belltaco 9y ago

It would be nice if commenters like you added a disclaimer that you work for Google in comments that hand wave away Google's privacy issues.

ocdtrekkie 9y ago
Eventually you just get the gist for who around here works at Google. ;) cromwellian, who responded to one of my comments here, is also a Googler. Arguably, DannyBee is correct that the real issue is that credit card companies are allowed to sell this data at all. But perhaps the danger of this practice is especially highlighted by the fact that Google is now one of the buyers.
- stephengillie 9y ago
  Should HN have an employer field next to user names, like the domain field next to the article name? It may have helped with the recent Docker issue.
  - ocdtrekkie 9y ago
    I don't think there's a lot of benefit to this. People would still debate whether or not they needed to disclose. Some people believe that if their posts are their personal views, they don't need to disclose. People might be more likely to use throwaway accounts for personal opinions or posts on unrelated topics. Since HN doesn't mandate any of this be provided (or accurate), it becomes useless. I usually don't disclose my employer on my profile... but I don't work at a startup or major tech company and no companies discussed here have any sort of relationship with mine. I think people should disclose they work for a company they are defending the position of online. But I don't see a way to force that issue in an environment that permits anon accounts.
    - DannyBee 9y ago
      I dunno, either people are there companies or they aren't. I am not my company, and a lot of people elsewhere aren't either. I don't think who we work for is really relevant at all unless they are trying to make offical statements. Either engage on the merits or don't. "Ignore this guy, he works for X" is not a useful line of argumentation. The only thing putting company names next to things would create, IMHO, is an echo chamber. (This is very different than journalists being paid to write specific articles or funded to do specific research, or even people paid quite specifically to astroturf) If we believe it's some magical generalized conflict of interest, why stop at company names. In any article about NIMBYism, should we require people post whjether they rent/own/own a home > 2 million/whatever. etc IMHO it's completely irrelevant to the merits of their argument. The merits don't change one way or the other. It seems the only usefulness would be able to filter/confirm biases. At that point, why bother having a discussion.

k-mcgrady 9y ago

>> IE It's not "better" when they sell it to someone who isn't Google It's better in the sense that those companies can probably do much less with purchase histories than Google as they have less total information on me (whereas Google has email, web history, photos, etc. if I allow them).

Paul-ish 9y ago

> Unfortunately, credit card companies/banks/etc have been selling purchasing histories, to pretty much all comers, for years. Do you have evidence of this?

hellbanner 9y ago
https://www.theguardian.com/money/2013/jun/08/supermarkets-get-your-data https://www.theguardian.com/money/2013/jun/08/supermarkets-g... https://www.forbes.com/forbes/welcome/?toURL=https://www.forbes.com/sites/moneybuilder/2013/04/29/this-week-in-credit-card-news-collecting-your-personal-data-why-you-should-pay-by-credit/ https://www.forbes.com/forbes/welcome/?toURL=https://www.for... http://www.thesimpledollar.com/how-credit-card-companies-make-money/ http://www.thesimpledollar.com/how-credit-card-companies-mak... https://www.creditfirm.net/blogs/mastercard-to-begin-selling-customer-data.html https://www.creditfirm.net/blogs/mastercard-to-begin-selling... http://www.businessinsider.com/credit-cards-sell-purchase-data-to-advertisers-2013-4 http://www.businessinsider.com/credit-cards-sell-purchase-da...