Re: [Bitcoin-development] Determine input addresses of a transaction
Am Mo, 24.10.2011, 16:55, schrieb Gavin Andresen: So my first shot at this is to go through the inputs of a transaction and see if the scriptSig field has only two opcodes. If that is the case, I assume that it is of the structure sig pubKey and calculate the Bitcoin address from pubKey. But then I started to wonder if this is safe. Can this be tricked somehow? Sure. There are lots of non-standard scriptPubKey scripts that will validate if given sig pubKey as input: a simple OP_NOP would work (do nothing, then check the top value on the stack and validate if it is not zero-- and pubKey is not zero). Aw, I see. So back to the drawing board for me. How about this: I make sure that sig is a proper signature from a green address key, by bringing my own scriptPubKey of just OP_CHECKSIG, complete the script to be sig pubKey OP_CHECKSIG, and run it and afterwards check the address by looking at pubKey? Would that be safe? (Even if it is a hackish solution that only works for certain type of transactions): Green addresses could be implemented as a second signature in the scriptSig. You'd have to hack your bitcoin client, but you could generate a transaction that had greensig sig pubKey ... as the input instead of sig pubKey. Interesting suggestion! So if I understand correctly, greensig would be the signature generated from signing the transaction with the key of a green address? Which would allow the rest of the transaction to be completely 'normal' and not require it to use specific inputs as such? Sounds good - I guess I never thought in this direction, as I always assumed doing anything 'non-standard' with the scripting language would create a number of knock-on problems. But you are saying, that this would still be considered standard? I guess I have to study this part of the source code more. Well, I guess I'm torn a little bit between two options: 1) Get something working reasonable fast to detect current green address style transactions. It's fine if it is a little bit of a hack, as long as it's safe, since I don't expect it to be merged with mainline anyway at this point. 2) Rethink how green transactions are created and verified and try to put something 'proper' together which has a chance of being merged at some point. For the moment I was going more with 1) because I got the impression, that green transactions are too controversial at this point to get them included in mainline. Criticism ranging from 'unnecessary, as 0-confirmation transactions are fairly safe today' to 'encourages too much centralization and therefore evil'. So how to people on this list feel about green transactions? Would people be interested in helping me with 2)? Regards, Jan -- The demand for IT networking professionals continues to grow, and the demand for specialized networking skills is growing even more rapidly. Take a complimentary Learning@Cisco Self-Assessment and learn about Cisco certifications, training, and career opportunities. http://p.sf.net/sfu/cisco-dev2dev ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] Determine input addresses of a transaction
On Tue, 2011-10-25 at 11:45 +0200, Jan Vornberger wrote: 1) Get something working reasonable fast to detect current green address style transactions. It's fine if it is a little bit of a hack, as long as it's safe, since I don't expect it to be merged with mainline anyway at this point. 2) Rethink how green transactions are created and verified and try to put something 'proper' together which has a chance of being merged at some point. For the moment I was going more with 1) because I got the impression, that green transactions are too controversial at this point to get them included in mainline. Criticism ranging from 'unnecessary, as 0-confirmation transactions are fairly safe today' to 'encourages too much centralization and therefore evil'. So how to people on this list feel about green transactions? Would people be interested in helping me with 2)? One possibility would be to create a peer sourced green address implementation. That is, each user could, individually decide to trust certain addresses as green and optionally, publish this trust. Basing things on the published trust, you could dynamically, as opposed to static hierarchies, evaluate the trustworthiness of each green address you haven't personally decided to trust. This would be somewhat involved implementation, though, as it would require heavy statistical calculations. - Joel -- The demand for IT networking professionals continues to grow, and the demand for specialized networking skills is growing even more rapidly. Take a complimentary Learning@Cisco Self-Assessment and learn about Cisco certifications, training, and career opportunities. http://p.sf.net/sfu/cisco-dev2dev ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] Determine input addresses of a transaction
Interesting suggestion! So if I understand correctly, greensig would be the signature generated from signing the transaction with the key of a green address? Sure. Or just a key. It wouldn't have to be an actual key used in the block chain. Sounds good - I guess I never thought in this direction, as I always assumed doing anything 'non-standard' with the scripting language would create a number of knock-on problems. It won't break the IsStandard checks, if that's what you mean. You can put any data you like into a scriptSig. In practice only data is useful, there's no purpose in having an actual script there (or at least, I wasn't able to find one yet). 1) Get something working reasonable fast to detect current green address style transactions. It's fine if it is a little bit of a hack, as long as it's safe, since I don't expect it to be merged with mainline anyway at this point. You could easily change the bitcoin code to detect such transactions - just look for scriptSigs that have 3 items instead of two, where the 3rd item is the right size to be a signature. Criticism ranging from 'unnecessary, as 0-confirmation transactions are fairly safe today' to 'encourages too much centralization and therefore evil' Heh, if that's a reference to my feedback, I definitely wouldn't describe such a feature as evil, that's rather strong :-) -- The demand for IT networking professionals continues to grow, and the demand for specialized networking skills is growing even more rapidly. Take a complimentary Learning@Cisco Self-Assessment and learn about Cisco certifications, training, and career opportunities. http://p.sf.net/sfu/cisco-dev2dev ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] Determine input addresses of a transaction
On Mon, Oct 24, 2011 at 10:29:57AM +0200, Jan Vornberger wrote: Hi there! As part of my green address endeavor, I'm currently trying to extend the 'gettransaction' call to include an extra field inputaddresses which should return a list of the Bitcoin addresses associated with the inputs of the transaction. Bitcoin transactions do not have input addresses - they optionally have addresses the input coins were last sent to. I understand that being able to have a 'from' address on a transaction is useful in certain cases, but it encourages using such 'from' addresses to identify transactions - which is imho the wrong way to go. As far as your green transactions idea is concerned, maybe we could provide an interface to mark certain addresses as 'trusted', and have an RPC call to request all incoming transaction that originate from trusted sources? -- Pieter -- The demand for IT networking professionals continues to grow, and the demand for specialized networking skills is growing even more rapidly. Take a complimentary Learning@Cisco Self-Assessment and learn about Cisco certifications, training, and career opportunities. http://p.sf.net/sfu/cisco-dev2dev ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] Determine input addresses of a transaction
So my first shot at this is to go through the inputs of a transaction and see if the scriptSig field has only two opcodes. If that is the case, I assume that it is of the structure sig pubKey and calculate the Bitcoin address from pubKey. But then I started to wonder if this is safe. Can this be tricked somehow? Sure. There are lots of non-standard scriptPubKey scripts that will validate if given sig pubKey as input: a simple OP_NOP would work (do nothing, then check the top value on the stack and validate if it is not zero-- and pubKey is not zero). If you assume the client has all previous transactions, then you could get the transaction input's prevout (from the memory pool or disk) and then ExtractAddress() from it. That is probably a bad idea for listtransactions, since fetching all the previous inputs from disk just so you can check to see if they're 'green' violates the a feature shouldn't cost anything if it is not being used design principle. You know, just thinking out loud... Green addresses could be implemented as a second signature in the scriptSig. You'd have to hack your bitcoin client, but you could generate a transaction that had greensig sig pubKey ... as the input instead of sig pubKey. The greensig will be ignored by old clients. The transactions is still considered 'standard'. But you could teach bitcoin to look for greensig signatures in wallet transactions... -- -- Gavin Andresen -- The demand for IT networking professionals continues to grow, and the demand for specialized networking skills is growing even more rapidly. Take a complimentary Learning@Cisco Self-Assessment and learn about Cisco certifications, training, and career opportunities. http://p.sf.net/sfu/cisco-dev2dev ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] Determine input addresses of a transaction
PKI would avoid the need for the trust aggregator to be consulted for each transaction. Obviously checking for revocation would be essential. The CA cert can state what kind of guarantee is available. Simon On 10/24/2011 09:25 AM, Mike Hearn wrote: You know, just thinking out loud... Green addresses could be implemented as a second signature in the scriptSig. I think this would solve one of the other issues I raised about the green address idea you can have some kind of trust aggregator sign the transactions. Merchants like MtGox that send would create a transaction, export it, upload it to the trusted authority which can just check IP address or something to verify it's really coming from MtGox, then sign it and broadcast it. -- The demand for IT networking professionals continues to grow, and the demand for specialized networking skills is growing even more rapidly. Take a complimentary Learning@Cisco Self-Assessment and learn about Cisco certifications, training, and career opportunities. http://p.sf.net/sfu/cisco-dev2dev ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development -- The demand for IT networking professionals continues to grow, and the demand for specialized networking skills is growing even more rapidly. Take a complimentary Learning@Cisco Self-Assessment and learn about Cisco certifications, training, and career opportunities. http://p.sf.net/sfu/cisco-dev2dev ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
