•   almost 12 years ago

unclaimed MintChip Value messages

"The Sender cannot stop or cancel the transaction after the value message has been created. "

What if the "value message" couldn't get to the "Receiver" for some unforeseeable reason? How do the sender retract the payment back?

BTW, has anyone got accepted to the contest yet? I submitted my enrollment around 4PM PDT yesterday. I hope that I am not too late for it.

  • 5 comments

  •   •   almost 12 years ago

    I just wanted to mention, I asked the same question to the developers support email (mintchipsupport@mint.ca), since some of the other posts indicated underlying technical details weren't being discussed on this forum. If I do get a response I'll post it, but based on the API itself I don't see anyway unless the application above it stores the existing transaction so it can be processed / recovered.

    Based on the API exposed, I had several concerns that I asked to the mint team directly. Hopefully we'll see this information as well as how the underlying design works in more detail.

  •   •   almost 12 years ago

    Thanks Kevin.

  •   •   almost 12 years ago

    I'm assuming it's exactly like cash. If you throw cash in an envelope and mail it, it could be lost forever.

    If you're writing an app, you'll want to be able to store and re-send value messages if required. Maybe embed a copy in a receipt.

  •   •   almost 12 years ago

    Agreed Terry, but what worries me is more that the application is left to the developer as an implementation detail.

    So crappy programmer x doesn't even bother writing a recovery mechanism, or hit's an unhandled exption and loses the transaction, and the value of that transaction is lost to the ether?

    This is the type of thing that I think is fundamental to the ecosystem, if every system should be able to support retransmission, have the device itself keep the log, so that the API can be used to just extract the backup copy. For a cup of coffee, maybe not a big deal, but if I'm loaning someone even a hundred bucks, I don't want it to disappear because my battery died at an inappropriate time.

  •   •   almost 12 years ago

    To answer Steven's original question: there is no way via the API to retract the state of the MintChip after a value message has been created. I assume that this was an intentional design decision to mitigate the risk of double-spending attacks (conversely, an online-only currency system would resist this type of attack).

    In the JavaScript API however, the mintChip.getLastCreatedValueMessage() method will return the latest value message created by the MintChip- useful for retrying a transaction immediately after failure.

    Remember that MintChip is a cash replacement protocol. It does not intend to afford the consumer protections that we are all accustomed to from the centralized nature of traditional banking systems (e.g. Interac, Visa).

    You should design your apps with this in mind. While online payments are indeed a use case for MintChip, such transactions are significantly more susceptible to Byzantine failures and your app will have to account for this.

    http://en.wikipedia.org/wiki/Byzantine_fault_tolerance

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