more about addresses bitcoin -qt

[kevinnem]

SO I was looking around on some of the exchange site and others.

some of them ask for the address that you are sending your information from - when you pay them. I thought this was not really important , and that it was a hard to get?

so lets say I sent 1 bit coin to someone would they "see" that is came to me .. or only that one coin came in to there address, and not know who it came from.

Sorry to be so noob, just a little confused on the mechanics of sending and recieveing.

[kevinnem]

here is an example I found

https://bitcointalk.org/index.php?topic=170654.0

it asks for "Reply with the Bitcoin address you are sending from and the total amount you are investing."

so I would have to know the address taht I send from???

[Blazr]

All addresses and transactions are completely public, so yes if you send someone BTC they will see the address it came from.

http://blockchain.info


http://blockchain.info/address/ <your BTC address here>

[eddyfitz]

All addresses and transactions are completely public, so yes if you send someone BTC they will see the address it came from.

http://blockchain.info


http://blockchain.info/address/ <your BTC address here>

But they may not know who own particular bitcoin address. So it grants you ability to stay anonymous if you want to

[DannyHamilton]

Although there are situations where it can perhaps be inferred that bitcoins were "sent from" an address, bitcoin doesn't really have a concept of an address that you are "sending from".  Furthermore, many of the bitcoin wallets hide this information from you. Anyone who is asking you to provide information about the address you are "sending from" does not properly understand how to use bitcoin, and I would be VERY WARY of engaging in any sort of transaction with them.

As an example, here's a transaction that was "sent to" 1BzEggcAztt4C7rbgWWg1ENYy1Wx1oSHwL
https://blockchain.info/tx/09f691b2263260e71f363d1db51ff3100d285956a40cc0e4f8c8c2c4a80559b1

Can you tell me where it was sent from?

[eddyfitz]

Although there are situations where it can perhaps be inferred that bitcoins were "sent from" an address, bitcoin doesn't really have a concept of an address that you are "sending from".  Furthermore, many of the bitcoin wallets hide this information from you. Anyone who is asking you to provide information about the address you are "sending from" does not properly understand how to use bitcoin, and I would be VERY WARY of engaging in any sort of transaction with them.

As an example, here's a transaction that was "sent to" 1BzEggcAztt4C7rbgWWg1ENYy1Wx1oSHwL
https://blockchain.info/tx/09f691b2263260e71f363d1db51ff3100d285956a40cc0e4f8c8c2c4a80559b1

Can you tell me where it was sent from?

Here's another interesting one sent to 1GtpSrGhRGY5kkrNz4RykoqRQoJuG2L6DS
https://blockchain.info/tx/997e5182f9d19bb8426cc0a7e862d29675ab19d05a7ddcd724aa612d893dd407

It appears to have come from: 35nGJpcQr4pYVyFVR3BPbdaWUSk6NBryUD
But that's not a valid bitcoin address.

After some googling I was not able to find answer on question "how to hide your sending address". As far as I understand transaction signing - you must include your public key to verify transaction encrypted by your private key. And public key can be converted to address. Can you please post more info on this?

[DannyHamilton]

Can you please post more info on this?

There are lots of threads pointing out that bitcoin has no such concept as a "from address".  Here's just one if you want to read a bit more about it.
https://bitcointalk.org/index.php?topic=196953.msg2048182#msg2048182

In general, for most transactions, we can use the scripts and signatures of the most common transaction type to create an abstraction that we can call a "from address", but it is a bad practice to count on this abstraction to hold true in all cases, and it is especially bad to ask a user to "send from" a particular address since most users are using wallets that don't allow them enough control over their transactions to make use of the abstraction in that way.

Bitcoin has inputs and outputs.  Outputs use scripts to set up requirements that need to be met in order to make use of the value associated with the output.  Inputs satisfy those requirements to include the value associated with the output in a transaction.  While the most common use of these scripts is to require a signature and public key from a private key that is associated with a particular hash, that is not the only possible use of a script.

[eddyfitz]

Ok, now it is more understandable that blockexplorer script just tries to match "from" address by looking on blockchain. But still I do not understand how to compose such transaction! Anyway, another question: why all those highjackers and hackers do not use such transactions when stealing coins? They usually smart guys and should know how to do this. Maybe existence of such transactions is just a bug that happens only when some pre requirements met? But not a "feature" of bitcoin system?

[Foxpup]

It appears to have come from: 35nGJpcQr4pYVyFVR3BPbdaWUSk6NBryUD
But that's not a valid bitcoin address.

Yes, it is:

Code:

validateaddress 35nGJpcQr4pYVyFVR3BPbdaWUSk6NBryUD
{
"isvalid" : true,
"address" : "35nGJpcQr4pYVyFVR3BPbdaWUSk6NBryUD",
"ismine" : false
}

If your client says it's not valid, then that's a bug in your client.

Ok, now it is more understandable that blockexplorer script just tries to match "from" address by looking on blockchain.

No, that's not what's actually happening. Every input has to satisfy the conditions of a previous output (in most cases, the condition is "provides a digital signature that matches the public key"), and every output has an address. The only exception to this rule is newly mined coins, which have no inputs. As a result, every transaction which doesn't generate newly mined coins has one or more clearly defined "from" addresses. There is no "trying" to match addresses, nor is it possible to hide them. However, most clients do not display this information, or allow you to determine which address(es) you'll be sending from if you have multiple addresses. Ordinary users never have any need for this information, and if anyone asks you for this information they're doing something horribly wrong.

[eddyfitz]

so there is no way to "sign" such transaction that will hide "from" address. Correct?
Or am I missing something again?

[Melon_Bread]

All addresses and transactions are completely public, so yes if you send someone BTC they will see the address it came from.

http://blockchain.info


http://blockchain.info/address/ <your BTC address here>

Also the info can be implaminted on other web sites as well

i.e. http://www.listentobitcoin.com/

[Foxpup]

so there is no way to "sign" such transaction that will hide "from" address. Correct?

Correct. There are, of course, many ways to hide the connection between a bitcoin address and your real-life identity, but there is no way to hide the address itself.

[eddyfitz]

Then I was right the first time. Thank you for saving me from confusion