HELP! Can't find sender address! URGENT!

[Mort432]

Hey, I'm running a very simple spreadsheet based exchange for a small altcoin, but I'm having some major issues.
I take orders via a GoogleDrive spreadsheet, and in order to verify if someone has sent a payment, I ask for their Bitcoin address, which I then compare to sender addresses when I recieve funds.

I recieved a number of payments to my exchange wallet, but none of the sender addresses match what I was given on the spreadsheet! They seem completely random.

I'm pretty buggered if I can't figure out which payment belongs to who. Can someone help me on this one? It's really urgent.

[RaTTuS]

you should do it the other way
generate an address for the user to send to then you know which one has sent when it arrives.

[Mort432]

you should do it the other way
generate an address for the user to send to then you know which one has sent when it arrives.

I think I probably am gonna have to do that, but for my own understanding, why doesn't my method work?

[AuroraHF]

you should do it the other way
generate an address for the user to send to then you know which one has sent when it arrives.

I think I probably am gonna have to do that, but for my own understanding, why doesn't my method work?

Your method works just fine, it is just the sender's fault for not putting the correct address. I recommend sending back the funds if you're unsure who is who.

[OnkelPaul]

With most wallets, there is no single address from which payments are sent.
So even if a user has one address in his wallet to which he usually receives payments, outgoing transactions may come from different addresses. These addresses are generated by the wallet software when there is "change" from a payment - this change amount is normally not stored in an address that was already in use, but into a new address. When a later payment is being done, it might be paid from the "change" address.

So for the future, switch to providing each sender with a unique address to which he should send.
The existing payments are a bit difficult to handle. The only safe method of finding out whether someone has sent a given payment is to let them sign some text with that payment's address - they can only do that if they actually control that address, and only if they control the address they could have sent the payment. However, organizing this will be a major hassle. Depending on the number of outstanding payments and your own costs for each, you could also decide to just eat the loss and don't pester your customers.

Onkel Paul

[Mort432]

Cheers all.