Bitcoin Forum

Other => Beginners & Help => Topic started by: Twipple on April 22, 2015, 04:59:47 PM



Title: Question about 2 addresses involved in a transaction
Post by: Twipple on April 22, 2015, 04:59:47 PM
I have a question about an address involved in a transaction.
Please let me know if this is a possibility.

If I have a deposit address to an exchange or gambling site: 15ZX2yUZio9HeSWUeWubxznQyaYcYFBFzB

https://blockchain.info/address/15ZX2yUZio9HeSWUeWubxznQyaYcYFBFzB

And that address has an outgoing transaction : https://blockchain.info/tx/d515a082b1df9b515e8f826cae84f41629183f26575bd014ba3d32ecddc9b633

Now you will see that 3 addresses are involved as senders.
19t4Cp3ftH3XTu6c4HhHTTpRP9TxDJVz87
15ZX2yUZio9HeSWUeWubxznQyaYcYFBFzB
1Fo6Uy8JWnV9SnDM5LBnYA8nnCQgbfbyDT

Now could it be possible that these addresses belong to an exchange which is just sweeping coins to one single address, from those 3 different addresses ?


Title: Re: Question about 2 addresses involved in a transaction
Post by: shorena on April 22, 2015, 06:11:09 PM
I have a question about an address involved in a transaction.
Please let me know if this is a possibility.

If I have a deposit address to an exchange or gambling site: 15ZX2yUZio9HeSWUeWubxznQyaYcYFBFzB

https://blockchain.info/address/15ZX2yUZio9HeSWUeWubxznQyaYcYFBFzB

And that address has an outgoing transaction : https://blockchain.info/tx/d515a082b1df9b515e8f826cae84f41629183f26575bd014ba3d32ecddc9b633

Now you will see that 3 addresses are involved as senders.

Just for precisions sake: there are no "sending addresses". The abve TX (d515...) spends 3 inputs that have previously been received with the addresses below. The transaction itself is only referencing the previous transactions though, never the addresses. The inputs used are from these transactions:

https://blockchain.info/tx/1114a697d9636307d31afaeb8cc0c55af37cd82ba7acaf80b333dcf67d7fb780
https://blockchain.info/tx/0b41521ae4b566a36e95dcc72ece20ad6c0925ae6481d8bb6c645e7d95e8e3ee
https://blockchain.info/tx/754c1604f0e0d86bb62e2335d1cfd727f4ea7aae742f7d3b49a51363312e20fc

19t4Cp3ftH3XTu6c4HhHTTpRP9TxDJVz87
15ZX2yUZio9HeSWUeWubxznQyaYcYFBFzB
1Fo6Uy8JWnV9SnDM5LBnYA8nnCQgbfbyDT

Now could it be possible that these addresses belong to an exchange which is just sweeping coins to one single address, from those 3 different addresses ?

It is commonly accepted as true that if a transaction spends 3 inputs and needs 3 different private keys to do so, these 3 private keys are in the possession of the same person/service. Technically it is possible that the 3 private keys (and corresponding addresses) belong to different people that just decided to create a transaction together.

tl;dr: Yes


Title: Re: Question about 2 addresses involved in a transaction
Post by: virtualx on April 22, 2015, 08:16:20 PM
I have a question about an address involved in a transaction.
Please let me know if this is a possibility.

If I have a deposit address to an exchange or gambling site: 15ZX2yUZio9HeSWUeWubxznQyaYcYFBFzB

https://blockchain.info/address/15ZX2yUZio9HeSWUeWubxznQyaYcYFBFzB

And that address has an outgoing transaction : https://blockchain.info/tx/d515a082b1df9b515e8f826cae84f41629183f26575bd014ba3d32ecddc9b633

Now you will see that 3 addresses are involved as senders.
19t4Cp3ftH3XTu6c4HhHTTpRP9TxDJVz87
15ZX2yUZio9HeSWUeWubxznQyaYcYFBFzB
1Fo6Uy8JWnV9SnDM5LBnYA8nnCQgbfbyDT

Now could it be possible that these addresses belong to an exchange which is just sweeping coins to one single address, from those 3 different addresses ?


A bitcoin transaction has x inputs and y outputs.   Multiple inputs are often listed in a transaction. All of the new transaction's input values (that is, the total coin value of the previous outputs referenced by the new transaction's inputs) are added up, and the total (less any transaction fee) is completely used by the outputs of the new transaction. There can be more than one output, and they share the combined value of the inputs.

The input addresses could belong to the same exchange.


Title: Re: Question about 2 addresses involved in a transaction
Post by: EcuaMobi on April 22, 2015, 11:47:50 PM
Now could it be possible that these addresses belong to an exchange which is just sweeping coins to one single address, from those 3 different addresses ?

By that you mean that the receiving address of that TX (17c2cHYmTT4LzRfi3UPP8ozcRHbxTrwca6 (https://blockchain.info/address/17c2cHYmTT4LzRfi3UPP8ozcRHbxTrwca6)) belongs to the same exchange and thus the coins are just being moved on the same wallet (or at least owner)? Let me know if I misunderstood you.

As shorena said, yes it's definitely possible. However it's not the only option. It's very likely that any external user of the exchange decided to withdraw 0.06 BTC and the exchange's wallet happened to have 3 unspent inputs that added exactly that amount, so no change was required (this is easier to happen because no fee was necessary).

Because a TX was created using the inputs of those 3 addresses then most probably (but not certainly) they belong to the same entity (the exchange) but you can't know anything for sure regarding the receiving address.


Title: Re: Question about 2 addresses involved in a transaction
Post by: odolvlobo on April 24, 2015, 03:00:14 AM
Now you will see that 3 addresses are involved as senders.
19t4Cp3ftH3XTu6c4HhHTTpRP9TxDJVz87
15ZX2yUZio9HeSWUeWubxznQyaYcYFBFzB
1Fo6Uy8JWnV9SnDM5LBnYA8nnCQgbfbyDT

Now could it be possible that these addresses belong to an exchange which is just sweeping coins to one single address, from those 3 different addresses ?

It is difficult to tell. It could be:
  • An exchange consolidating bitcoins from deposit addresses.
  • A user sending bitcoins, and correctly using addresses by not reusing them.
  • A coin-join transaction where multiple users send bitcoins in single transaction in order to thwart wallet trackers.

The amount is so tiny that it is probably not the first or third.