How to determine the sender?

[naituida]

Question rises from examples like :
http://blockchain.info/tx/cc4379b54e277492893a6b81a6a838b6bf308caa2ccc02720579277ac50dcf47

and

http://blockchain.info/tx/ed758629beeeac05bb61ffbadcb5a126a806c903b60c2f02489f56b6ba6d73d4

The first link is an example showing trasaction from multiple senders and at most two receivers ( refering from Ch 9 in orginal bitcoin paper).
Suppose we have a transaction as A and B and C send total amount of 5 bitcoins to D and E. From the transaction, we can tell how many
bitcoins sent by A or B or C and how many received by D or E. But how can we tell how many bitcoins sent from A to D?


The second link is an example of transaction from single sender to multiple receivers(more than 2) which is not shown in origianl paper.
Is this introduced by newer version in bitcoin?

Thx!

[Foxpup]

The first link is an example showing trasaction from multiple senders and at most two receivers ( refering from Ch 9 in orginal bitcoin paper).
Suppose we have a transaction as A and B and C send total amount of 5 bitcoins to D and E. From the transaction, we can tell how many
bitcoins sent by A or B or C and how many received by D or E. But how can we tell how many bitcoins sent from A to D?

A, B, and C are almost certainly different addresses in the same wallet, and belong to one person. But in case you're wondering, clicking "Show scripts & coinbase" in blockchain.info will show you exactly how much came from each address.

The second link is an example of transaction from single sender to multiple receivers(more than 2) which is not shown in origianl paper.
Is this introduced by newer version in bitcoin?

No, this has always been around. In fact, it's pretty rare to find a transaction that doesn't send to two or more addresses, since transactions usually have to make change.

Both of these situations are explained in Chapter 9 of the whitepaper. Note that there's actually no limit on the number of outputs, and although a transaction from one person to another will normally only have two outputs, it is possible to use more than two outputs, for example when sending to multiple people with one transaction. The whitepaper only provides examples of the most common situation.

[Stephen Gornick]

But how can we tell how many bitcoins sent from A to D?

De-linking the inputs from outputs helps privacy.

Here's a mixing service that uses this to help improve privacy:

 - http://blog.ezyang.com/2012/07/secure-multiparty-bitcoin-anonymization/


And, of course, the recipient knows the sender when a new bitcoin address is given for each transaction.

[naituida]

A, B, and C are almost certainly different addresses in the same wallet, and belong to one person. But in case you're wondering, clicking "Show scripts & coinbase" in blockchain.info will show you exactly how much came from each address.

We can find how much BTC came from A, but can we tell how much does A want to send to D and how much to E?

[Foxpup]

They're just addresses, they don't "want" anything. More to the point, A, B, and C are addresses that belong to either the same person (who probably doesn't even know or care about individual addresses in the same way that a person using cash doesn't bother keeping track of individual coins and notes), or (though this is far less likely) multiple people acting jointly as a single entity (in which case there is no way to tell what each individual was thinking, other than that they were all in complete agreement as to how the money was to be distributed - exactly how they came to that agreement is their own business and no-one else's).