I think the bitcoin: URL is a good start

https://bt.irlbtc.com/view/33490.0

Sites could generate this, and the client could listen for them, so that it takes only a push of a button (or a drag/drop action, if you prefer for security reasons) to send the payment to the client. The client will then ask for confirmation before sending the payment to the network.

I would strongly discourage this approach. It requires the online store to keep the wallet online, which is extremely hard to secure properly. It also requires setting up bitcoind daemon and custom JSON/RPC integration, which is not trivial for most Merchants. It's far better to use one of existing merchants solutions.

Well unfortunately you are a bit biased.  After recent events the reliability of third parties to manage bitcoins must always be considered lower then managing your own wallets and security.  The entire point of bitcoin is to eliminate the need for third parties, that's a security feature you should not attempt to circumvent unless you thoroughly understand and can tolerate the risks involved.

Also, in point of fact. You do not need to keep a wallet that contains coins in it on the server if you are only receiving payments.  You can pre-generate a number of bitcoin addresses on a secure client and load them into a database table on your site.  Even if you do use a normal server side bitcoind you can also keep a local copy of the same wallet, so that you can regularly sweep money to your trading account of offline savings wallet.

This is EXACTLY the kind of mistake I'm talking about. That service is not providing anything you can't easily do with a bitcoind. And it's opening you up to a HUGE security hole. Don't know that that hole is? Then that is exactly why you should not be using third party solutions.  At least one security hole on this site is easy to identify, but that is not true of most 3rd party sites.  You'll never know all the security liabilities.  With bitcoind you know what you're getting into, and it just isn't that much harder to do a json request then to get a post notification from a 3rd party site.

Tell me why are you trying to avoid using the proper API?  You just don't want to read the manual? Reading the manual and learning how bitcoin works is a small price to pay for the security and reliability it can offer if used properly.

BitcoinNotify looks like an usable service. 2 Others:

https://walletbit.com (currently writing a PHP class for this one, but requires customer to be signed up with them as well)
and
http://www.bitcoinpayflow.com

Thanks for recognition.


The major difference is that BitcoinNotify does not store your coins.

Payments go directly from a customer to your private wallet (possibly disconnected from the network).

On the contrary, BitcoinPayflow and WalletBit are very nicely designed but you need to trust in the perfect security of these services, as the wallets are being kept online.

bitcoind can monitor the blockchain without access to your receiving wallet just as easily as a third party service.



Do you see it now?

Considering how many people trusted mybitcoin, and a startling willingness to abandon a key security feature of bitcoin I think it's important that everyone understand that security is a multifaceted problem. You need to be very conscious when you are explicitly or implicitly trusting a 3rd party.  Bitcoin as a system is well designed, but you eliminate the value of that design if you start working around it buy using online wallets, merchant services etc.  

I'm not saying you can't use those things.  But why use them if the built in tools do almost exactly the same thing more securely? If you understand how to use bitcoin, and you have a specific need for a 3rd party service, then you should also understand as well as possible what risk you are absorbing.  A LOT of people on this list lost money because they failed to notice when that where circumventing their own security.  

Understand first. Trust second.

j

P.S. Note that I'm not saying this service is bad.  If you know a site is bad security questions are easy to answer.  I'm simply rebutting the assertion above that it is better to trust a 3rd party then the bitcoind and API.

P.P.S:

This just proves that neither of you are considering ALL of the security issues.  It's actually really hard to do. That's why you should just try to use the bitcoind system if you can.  It's vetted, peer reviewed open source, and well understood by a large community who could help you if you have trouble.

I thought Josh was talking about the fact that the only authorization is your IP address:

...

Someone might be able to forge a 'payment sent' request to your user's website by simple spoofing your IP address since it appears there is no authentication or token or anything sent in the POST request itself to prevent a fake payment acknowledgement.

An IP address spoofing explanation is here:
http://www.shaadiya.com/ask/2007/06/15/how-to-spoof-ip-address-hackers-view-and-the-way-to-protect-sites-with-this-fake/

If I could spoof your address I could send fake payment acknowledgements to all your users.

But, I'll be honest, I only took a quick look at your docs and I don't know your system nor have I tried it yet so maybe I'm just blowing smoke out my ass.

But if I'm right, you should probably fix that.

you could try reading the api documentation for liberty reserve, alertpay, etc for security ideas.