Re: [Bitcoin-development] BIP for Proof of Payment

2015-06-17 Thread Kalle Rosenbaum
2015-06-16 21:48 GMT+02:00 Pieter Wuille pieter.wui...@gmail.com: I don't see why existing software could create a 40-byte OP_RETURN but not larger? The limitation comes from a relay policy in full nodes, not a limitation is wallet software... and PoPs are not relayed on the network. You are

Re: [Bitcoin-development] BIP for Proof of Payment

2015-06-16 Thread Kalle Rosenbaum
Another thing worth mentioning is that an SPV wallet cannot validate a PoP without fetching the input transactions of the PoP from an external (not bitcoin network) source, for example chain.com or some other trusted full node's API. The validation of the PoP depends on the external source(s)

Re: [Bitcoin-development] BIP for Proof of Payment

2015-06-16 Thread Kalle Rosenbaum
Thank you for the clarification Tom! /Kalle 2015-06-16 16:05 GMT+02:00 Tom Harding t...@thinlink.com: On 6/16/2015 5:12 AM, Kalle Rosenbaum wrote: 2015-06-16 7:26 GMT+02:00 Tom Harding t...@thinlink.com: Kalle goes to some trouble to describe how merchants need to ensure that they only

Re: [Bitcoin-development] BIP for Proof of Payment

2015-06-16 Thread Pieter Wuille
I don't see why existing software could create a 40-byte OP_RETURN but not larger? The limitation comes from a relay policy in full nodes, not a limitation is wallet software... and PoPs are not relayed on the network. Regarding sharing, I think you're talking about a different use case. Say you

Re: [Bitcoin-development] BIP for Proof of Payment

2015-06-15 Thread Pieter Wuille
I did misunderstand that. That changes things significantly. However, having paid is not the same as having had access to the input coins. What about shared wallets or coinjoin? Also, if I understand correctly, there is no commitment to anything you're trying to say about the sender? So once I

Re: [Bitcoin-development] BIP for Proof of Payment

2015-06-15 Thread Tom Harding
Shared wallets were discussed earlier as a feature. If you pay a for dry cleaning with a shared wallet, a different 1-of-N signer can pick up the clothes with no physical transfer of a claim check, by proving the money that paid for the cleaning was his. Many kinds of vouchers can be

Re: [Bitcoin-development] BIP for Proof of Payment

2015-06-06 Thread Pieter Wuille
On Sat, Jun 6, 2015 at 5:05 PM, Kalle Rosenbaum ka...@rosenbaum.se wrote: What do you gain by making PoPs actually valid transactions? You could for example change the signature hashing algorithm (prepend a constant string, or add a second hashing step) for signing, rendering the

Re: [Bitcoin-development] BIP for Proof of Payment

2015-06-06 Thread Pieter Wuille
What do you gain by making PoPs actually valid transactions? You could for example change the signature hashing algorithm (prepend a constant string, or add a second hashing step) for signing, rendering the signatures in a PoP unusable for actual transaction, while still committing to the same

Re: [Bitcoin-development] BIP for Proof of Payment

2015-06-06 Thread Kalle Rosenbaum
The idea is to simplify implementation. Existing software can be used as is to sign and validate PoPs. But I do agree that it would be a cleaner specification if we would make the PoP invalid as a transaction. I'm open to changes here. I do like the idea to prepend a constant string. But that

Re: [Bitcoin-development] BIP for Proof of Payment

2015-06-06 Thread Luke Dashjr
On Saturday, June 06, 2015 2:35:17 PM Kalle Rosenbaum wrote: Current methods of proving a payment: * Signing messages, chosen by the server, with the private keys used to sign the transaction. This could meet 1 and 2 but probably not 3. This is not standardized either. 4 Could be met if

[Bitcoin-development] BIP for Proof of Payment

2015-06-06 Thread Kalle Rosenbaum
Hi Following earlier posts on Proof of Payment I'm now proposing the following BIP (To read it formatted instead, go to https://github.com/kallerosenbaum/poppoc/wiki/Proof-of-Payment-BIP). Regards, Kalle Rosenbaum pre BIP: BIP number Title: Proof of Payment Author: Kalle Rosenbaum

Re: [Bitcoin-development] BIP for Proof of Payment

2015-06-06 Thread Pieter Wuille
On Sat, Jun 6, 2015 at 5:18 PM, Luke Dashjr l...@dashjr.org wrote: I also agree with Pieter, that this should *not* be so cleanly compatible with Bitcoin transactions. If you wish to share code, perhaps using an invalid opcode rather than OP_RETURN would be appropriate. Using an invalid

Re: [Bitcoin-development] BIP for Proof of Payment

2015-06-06 Thread Tom Harding
On Jun 6, 2015 8:05 AM, Kalle Rosenbaum ka...@rosenbaum.se wrote: I'm open to changes here. I suggest: - Don't include any real outputs. They are redundant because the txid is already referenced. - Start the proof script, which should be invalid, with a magic constant and include space for

Re: [Bitcoin-development] BIP for Proof of Payment

2015-06-06 Thread Luke Dashjr
On Saturday, June 06, 2015 9:25:02 PM Kalle Rosenbaum wrote: * The pop output will have value 0. Why not have it be -1 to make it completely invalid as a transaction? Luke --