5 ms·

At the end of the day, balance sheets always balance, every transaction has two sides, and privacy for only one side of every transaction is impossible.

igorkraw 6y ago
Yes it is. You just write down "got 5 bucks from customer" and submit it to the tax office. Now one side is anonymous (customers) and the other not (merchant)
- Ar-Curunir 6y ago
  And before that the customer writes down “received 5 bucks”. Then you match up the two and can track the customer’s spending habits
  - littlestymaar 6y ago
    Well, If all you have is “A spent $5” and “B received $5” you are still missing a lot of info to identify that A and B are part of the same transaction (there are thousands of $5 trades every day) But that's not even how Taler works: you withdraw an arbitrary amount of Taler (say $50), this is what is recorded on the consumer side, but then you have anonymous tokens (exactly like coins and bills) that you can spend without connecting to anything: only the supplier need to have a connection to a certification entity (which ensure no double spending).
    - runeks 6y ago
      What is the denomination of these tokens? Do I hand over 500 one-cent tokens to pay $5?
      - littlestymaar 6y ago
        That's the coolest thing about Taler: there is a thing called “the refresh protocol”[1] which allows you to obtain change after a transaction: that is, for instance you pay with a $7 token for your $5 transaction, and you get a $2 change token! [1]: section “4.7.4. Refreshing and Linking” in this paper https://ged.univ-rennes1.fr/nuxeo/site/esupversions/41aac1ac-3074-4b0e-9087-cee5f58ce0b2?inline https://ged.univ-rennes1.fr/nuxeo/site/esupversions/41aac1ac...
        runeks 6y ago
        That is pretty cool! So, basically, if a merchant requests payment of $5 and the buyer only has a $4 and a $3 token then the buyer exchanges her $3 token for three $1 tokens with the exchange (without involvement of the merchant) and then pay the merchant with a $4 and a $1 token?
  - igorkraw 6y ago
    If you go to your ATM and get 5 bucks, and then go to the cafe to pay a coffee with it and it's registered in their system, this is the exact same scenario, you realize that?
helen___keller 6y ago
In that case, please enlighten me how to pierce the veil. For the sake of argument, you can play the role of an exchange arbiter - you have full visibility into every transaction. On a given day you're signing a few billion in IOUs into existence from users, while paying out a few billion in IOUs from merchants. Since you are providing blind signatures, you essentially have two ledgers: one is transactions of the form (user, token_value, signed_at) and a second is transactions of the form (merchant, token_value, redeemed_at). How do you suggest the exchange matches user to merchant from this data?
- zaphirplane 6y ago
  Not the person u are replying to Can a hash not be calculated for the iou, does it have an identifier ? The exchange can log those
  - littlestymaar 6y ago
    It cannot, the anonymity guarantees are exposed in the Taler paper[1]: https://ged.univ-rennes1.fr/nuxeo/site/esupversions/41aac1ac-3074-4b0e-9087-cee5f58ce0b2?inline https://ged.univ-rennes1.fr/nuxeo/site/esupversions/41aac1ac...
- monoideism 6y ago
  I've never looked into Taler before this, but they could be matched by token value and approximate time, no?
  - helen___keller 6y ago
    Token value perhaps, under very low volume (think single digit users). But imagine millions or billions of dollars a day in transaction volume, looking at a $5 payment at a cafe and then trying to figure out which of the people whose been assigned a $5 token to in the past month might have shopped there - it would be absolutely futile. Taler wallets just sit there until you use them, much like cash. Realistically, there would be too many degrees of freedom to create a matching from merchant to user, even if we additionally assumed a ton of metadata about user/merchant location and such.
littlestymaar 6y ago
So Zcash developers feel threatened enough about Taler to spread FUD about it. Sounds like a positive signal to me ;).
- waynesonfire 6y ago
  Hahah, nice.
- tffg 6y ago
  Lmao

igorkraw 6y ago

Yes it is. You just write down "got 5 bucks from customer" and submit it to the tax office. Now one side is anonymous (customers) and the other not (merchant)

Ar-Curunir 6y ago
And before that the customer writes down “received 5 bucks”. Then you match up the two and can track the customer’s spending habits
- littlestymaar 6y ago
  Well, If all you have is “A spent $5” and “B received $5” you are still missing a lot of info to identify that A and B are part of the same transaction (there are thousands of $5 trades every day) But that's not even how Taler works: you withdraw an arbitrary amount of Taler (say $50), this is what is recorded on the consumer side, but then you have anonymous tokens (exactly like coins and bills) that you can spend without connecting to anything: only the supplier need to have a connection to a certification entity (which ensure no double spending).
  - runeks 6y ago
    What is the denomination of these tokens? Do I hand over 500 one-cent tokens to pay $5?
    - littlestymaar 6y ago
      That's the coolest thing about Taler: there is a thing called “the refresh protocol”[1] which allows you to obtain change after a transaction: that is, for instance you pay with a $7 token for your $5 transaction, and you get a $2 change token! [1]: section “4.7.4. Refreshing and Linking” in this paper https://ged.univ-rennes1.fr/nuxeo/site/esupversions/41aac1ac-3074-4b0e-9087-cee5f58ce0b2?inline https://ged.univ-rennes1.fr/nuxeo/site/esupversions/41aac1ac...
      - runeks 6y ago
        That is pretty cool! So, basically, if a merchant requests payment of $5 and the buyer only has a $4 and a $3 token then the buyer exchanges her $3 token for three $1 tokens with the exchange (without involvement of the merchant) and then pay the merchant with a $4 and a $1 token?
- igorkraw 6y ago
  If you go to your ATM and get 5 bucks, and then go to the cafe to pay a coffee with it and it's registered in their system, this is the exact same scenario, you realize that?

helen___keller 6y ago

In that case, please enlighten me how to pierce the veil. For the sake of argument, you can play the role of an exchange arbiter - you have full visibility into every transaction. On a given day you're signing a few billion in IOUs into existence from users, while paying out a few billion in IOUs from merchants. Since you are providing blind signatures, you essentially have two ledgers: one is transactions of the form (user, token_value, signed_at) and a second is transactions of the form (merchant, token_value, redeemed_at). How do you suggest the exchange matches user to merchant from this data?

zaphirplane 6y ago
Not the person u are replying to Can a hash not be calculated for the iou, does it have an identifier ? The exchange can log those
- littlestymaar 6y ago
  It cannot, the anonymity guarantees are exposed in the Taler paper[1]: https://ged.univ-rennes1.fr/nuxeo/site/esupversions/41aac1ac-3074-4b0e-9087-cee5f58ce0b2?inline https://ged.univ-rennes1.fr/nuxeo/site/esupversions/41aac1ac...
monoideism 6y ago
I've never looked into Taler before this, but they could be matched by token value and approximate time, no?
- helen___keller 6y ago
  Token value perhaps, under very low volume (think single digit users). But imagine millions or billions of dollars a day in transaction volume, looking at a $5 payment at a cafe and then trying to figure out which of the people whose been assigned a $5 token to in the past month might have shopped there - it would be absolutely futile. Taler wallets just sit there until you use them, much like cash. Realistically, there would be too many degrees of freedom to create a matching from merchant to user, even if we additionally assumed a ton of metadata about user/merchant location and such.

littlestymaar 6y ago

So Zcash developers feel threatened enough about Taler to spread FUD about it. Sounds like a positive signal to me ;).

waynesonfire 6y ago
Hahah, nice.
tffg 6y ago
Lmao