BitcoinTalk
A newb's test - anyone want to buy a picture for $1?

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Hello all. I've decided to give Bitcoin a try. As a test, I want to see if I can make $1 USD from selling a picture. According to this, 500 Bitcoins should roughly be a dollar (after PayPal fees), right? If I understand this correctly, I should be told the Bitcoin Address of anyone who Sends me Bitcoins, right? And you have the ability to attach messages to the Send? If so, then I guess I could Send 0 Bitcoins in return, with a message containing a download link for the full image. Is this how things are supposed to work, or am I mistaken? To get the picture, please send the coins to me and then send a Private Message stating the time you sent them. I will reply to your Private Message with a link to the picture.

The image I'm selling is my own creation, with a resolution of 1280x960 - great for a desktop background. Here's a low-quality preview:


Anyway, it's been a pleasure to meet you all. My Address is 1BHtsCnpmTvpgJEP7eMKEVhpJFunxSM8vq. If this generates any interest, I could offer some more of my pictures...
Hmm.. I am not sure if you can send a 0-coin payment. Can anyone confirm this?
Simple solution to that. If it's for sale for 500 coins, just have them send 501 and send 1 back Smiley
I assume you tested it, then, and it didn't work? Very well. Hm, what about decimals? I notice that my balance is 0.00. Could I send 0.01 coins?
I, have not tested it. Just giving ideas. Besides, 1 coin, according to Liberty Standard's exchange, is less than a penny. I wouldn't get hung up on decimals.
Hello all. I've decided to give Bitcoin a try. As a test, I want to see if I can make $1 USD from selling a picture. According to this, 500 Bitcoins should roughly be a dollar (after PayPal fees), right? If I understand this correctly, I should be told the Bitcoin Address of anyone who Sends me Bitcoins, right? And you have the ability to attach messages to the Send? If so, then I guess I could Send 0 Bitcoins in return, with a message containing a download link for the full image. Is this how things are supposed to work, or am I mistaken?

Unfortunately you can't attach a message when you send to a Bitcoin address. It's possible only when sending to an IP. Sending 0 coins is also not possible.

If you want to track payments, you can give a new Bitcoin address to each customer. How to make a new address: Options -> Change your address. We could perhaps make this easier by adding next to "Send Coins" a button "Receive Coins", which would create you the new address and ask for its label.
You can't send messages to Bitcoin users unless it's the IP? That seems unnecessary. Any reasoning behind this? I think people will use Bitcoin addresses a lot more often than the IP address when sending or receiving coins.
No messages that way? That seems less than ideal. Very well, what would be a more correct way to do this?

For now, if anyone sends 500 coins and tells me in Private Message the time they sent it, I shall respond with a link to the picture.
You can't send messages to Bitcoin users unless it's the IP? That seems unnecessary. Any reasoning behind this? I think people will use Bitcoin addresses a lot more often than the IP address when sending or receiving coins.

I think it was some technical limitation. Satoshi could tell more about this?
Yes, it's a technical limitation.  Sending by bitcoin address enters the transaction into the network and the recipient discovers it from the network.  You don't connect directly with them and they don't have to be online at the time.

I very much wanted to find some way to include a short message, but the problem is, the whole world would be able to see the message.  As much as you may keep reminding people that the message is completely non-private, it would be an accident waiting to happen.

Unfortunately, ECDSA can only sign signatures, it can't encrypt messages, and we need the small size of ECDSA.  RSA can encrypt messages, but it's many times bigger than ECDSA.
Yes, encryption of messages would be a very good thing... So the problem is not that you can't store the message on the network, but rather, that you do not yet have a good way of encrypting it?
I certainly wouldn't mind a larger Bitcoin application if it meant we could send an encrypted message along with each transaction. Right now I require an email message from customers who send me bitcoins. This is not ideal because if another person knew about a transaction that was occurring, they could take credit for the transaction by sending a message before the person who sent the bitcoins. About how many MB do you think it would add? Of course these messages will add to the size of the confirmation blocks being stored, so there should probably be a maximum size. Perhaps 256 characters would be a good maximum since the maximum size of an email address is 254 characters.

It would also be nice if transactions included a return address so that if a product or service being purchased can't be delivered the seller could more easily and reliably refund the bitcoins.
A balance between extended transaction data while NOT becoming an instant messenger client would be nice. Tongue
Right now I require an email message from customers who send me bitcoins. This is not ideal because if another person knew about a transaction that was occurring, they could take credit for the transaction by sending a message before the person who sent the bitcoins.

Why don't you make them send the email before the transaction? Then you could reply to that email with a new and unique bitcoin address. You don't even need to use email, it would be equally secure, although not that anonymous, to announce the customers email together with the bitcoin address on the frontpage of your site.

The method you are using now is equal to someone sending you cash in an envelope anonymously, including a note with the time he posted it, after which you send goods back to the first person calling you stating the time and amount in the envelope. (Including the mailman and anyone who has access to you mailbox).  Tongue

Sending the email before the transaction is equal to someone calling you, getting a unique box address which to send the money to. When the money arrives to that post box, you send the goods to the customer.
The recommended ways to do a payment for an order:
1) The merchant has a static IP, the customer sends to it with a comment.
2) The merchant creates a new bitcoin address, gives it to the customer, the customer sends to that address.  This will be the standard way for website software to do it.

RSA vs ECDSA: it's not the size of the executable but the size of the data.  I thought it would be impractical if the block chain, bitcoin addresses, disk space and bandwidth requirements were all an order of magnitude bigger.  Also, even if using RSA for messages, it would still make sense to do all the bitcoin network with ECDSA and use RSA in parallel for only the message part.  In that case, everything that's been implemented up to now would be implemented exactly as it has been.

We can figure out the best way to do this much later.  It could use a separate (maybe existing) e-mail or IM infrastructure to pass messages, and instead of RSA, maybe just put a hash of the message in the transaction to prove that the transaction is for the order described in the message.  The message would have to include a salt so nobody could brute force the hash to reveal a short message.