Resubmit raw transactions

[bg002h]

My apologies if this is the wrong forum.

If I send money to Bob using my 1SendtoBobAddressL0r3mIp5umD0lr address and Alice sends me money to that same address, could Bob rebroadcast my raw transaction to get double paid?

[bg002h]

The answer has got to be no...right?  I mean, I could scan the block chain and look for all repeatable transactions and wreak no small amount of havoc otherwise...

That sure would teach folks not to re-use addresses!

[kjj]

No.*

Transactions involve previous transactions.  There are no accounts, no addresses, no balances.

*  Once upon a time, it was possible to create identical chains of transactions.  The door has been closed, and if I recall correctly, it was never used for evil.

[bg002h]

No.*

Transactions involve previous transactions.  There are no accounts, no addresses, no balances.

*  Once upon a time, it was possible to create identical chains of transactions.  The door has been closed, and if I recall correctly, it was never used for evil.

This is the part I find confusing; inputs are different than addresses?  I suppose they must be, by what you're saying.  

What if the change address was the same as the sending address?

[kjj]

There are no addresses.

A transaction is just two lists.  The first list is a list of past transactions that are being redeemed (the inputs), the second list is a set of outputs and the conditions necessary to redeem them in the future.  In a standard transaction, the redemption conditions are constructed from the address.

The input list is composed of {txhash,seq} pairs.  The txhash is the hash of the transaction, and seq is the position in the list.  txhashes are unique (with a few historic exceptions that users are safe to ignore), so the second transaction to that address will be different from the old one.

[dserrano5]

*  Once upon a time, it was possible to create identical chains of transactions.

Wow, got a link to this?

[kjj]

*  Once upon a time, it was possible to create identical chains of transactions.

Wow, got a link to this?

Not off the top of my head, but look for the discussion around BIP 34.

The whole point of adding the height to the coinbase was the make each generate transaction unique.  Prior to that, it was possible to create duplicates.  And since duplicate generations would have identical hashes, you could, in theory, make a chain of transactions starting from one generate, and then duplicate the entire chain later.

It would be difficult to trick someone using this quirk, but not impossible.  Also, it was ugly.  Which is why it got fixed.

[dserrano5]

Not off the top of my head, but look for the discussion around BIP 34.

And BIP 30 too. Thank you!