3 ms·

Why would the Drop need to retain half the serial number? They have received the goods.

yesbabyyes 7y ago
I'm not sure the drop retains half the serial number? GP claims the drop rips the bill in half, and hands the part with the (full, I seem to recall US dollar bills have the serial number on the bottom left) serial number to the courier. The courier can prove they delivered to the right drop, and the bill being ripped in half will ensure it won't be used again.
- RaceWon 7y ago
  > I seem to recall US dollar bills have the serial number on the bottom left Our money (US Currency) has two (of the same) serial numbers on each bill; one on the lower left and one on the upper right for dollar bills. Other denominations also have two; one on each side of the front of the bill, however they are in opposite places i.e. upper left, and lower right--at least the current bills in my wallet are that way.
bartwe 7y ago
Ensuring the code isn't reused, to put in a ledger, to avoid some kind of replay attack, having someone pretend to be the courier and get the key to then replay to the real courier. Dunno, probably many many things avoided by making the key not usable but still verifiable.
- qrbLPHiKpiux 7y ago
  Very important to never reuse a code, or one time pad. Perfect forward secrecy.
- trickstra 7y ago
  I can think of only one scenario when it would make sense to destroy the bill - if the Drop is still able to present the whole bill after the Courier says they delivered the package, that is a proof the Courier is lying or got played and didn't verify the code. Drop is the one who has motivation to keep the bill intact, Courier uses the bill as proof of delivery, and cuts it in half just to be safe that someone from the Drop won't stop them at gunpoint after the delivery, stealing the whole bill.
p1mrx 7y ago
Well, the Drop can take the bills back to the bank. "The corners fell off. Can I have some fresh ones?"
- steevdave 7y ago
  But they can't use that specific one again, it doesn't matter if they take the bill to a bank and get new ones, because the serial numbers won't be the same.
- inlined 7y ago
  I doubt a Drop cares enough about $1 to repeatedly engage in suspicious behavior with a bank
  - p1mrx 7y ago
    That's the joke.
afiori 7y ago
In a criminal organization security and accountability are a more complex topic, but I would say that this way the one serial number the drop keep is a proof of identity, while the serial number the courier keep is a receipt.

I'm not sure the drop retains half the serial number? GP claims the drop rips the bill in half, and hands the part with the (full, I seem to recall US dollar bills have the serial number on the bottom left) serial number to the courier. The courier can prove they delivered to the right drop, and the bill being ripped in half will ensure it won't be used again.

RaceWon 7y ago
> I seem to recall US dollar bills have the serial number on the bottom left Our money (US Currency) has two (of the same) serial numbers on each bill; one on the lower left and one on the upper right for dollar bills. Other denominations also have two; one on each side of the front of the bill, however they are in opposite places i.e. upper left, and lower right--at least the current bills in my wallet are that way.

bartwe 7y ago

Ensuring the code isn't reused, to put in a ledger, to avoid some kind of replay attack, having someone pretend to be the courier and get the key to then replay to the real courier. Dunno, probably many many things avoided by making the key not usable but still verifiable.

qrbLPHiKpiux 7y ago
Very important to never reuse a code, or one time pad. Perfect forward secrecy.
trickstra 7y ago
I can think of only one scenario when it would make sense to destroy the bill - if the Drop is still able to present the whole bill after the Courier says they delivered the package, that is a proof the Courier is lying or got played and didn't verify the code. Drop is the one who has motivation to keep the bill intact, Courier uses the bill as proof of delivery, and cuts it in half just to be safe that someone from the Drop won't stop them at gunpoint after the delivery, stealing the whole bill.

p1mrx 7y ago

Well, the Drop can take the bills back to the bank. "The corners fell off. Can I have some fresh ones?"

steevdave 7y ago
But they can't use that specific one again, it doesn't matter if they take the bill to a bank and get new ones, because the serial numbers won't be the same.
inlined 7y ago
I doubt a Drop cares enough about $1 to repeatedly engage in suspicious behavior with a bank
- p1mrx 7y ago
  That's the joke.

afiori 7y ago

In a criminal organization security and accountability are a more complex topic, but I would say that this way the one serial number the drop keep is a proof of identity, while the serial number the courier keep is a receipt.