I got a payment and need to confirm that the user in forum that claims that its her payment is the real person. She added her username in the transaction. So now im wondering if that is proof enough. Can only the owner of the address set this note?

No! people should read and pay only from addresses they control 

I suspect it could be done with a native client plugin but if it needs to be dependant on a native plugin then it might as well just be a standalone desktop lite client. May be some time in the future but for the moment my priority is to revise the iphone app and then get multisig working and/or support for a hardware wallet.


I think this is just a limitation of Bitcoin-Qt though? if the client tests both the compressed and compressed version of the key signing should be possible. The correct pub key will now been shown now.


Usernames were spidered from signatures on this forum and since you can put anything in your own signature it isn't good verification. Notes also be added when a transaction is submitted to blockchain.info which is slightly better proof because because the person that submitted it is likely to be the signer, however it still not 100% verification. You can sign and verify a message in the web interface.

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Changes:

- The mnemonic phrase now encodes both the wallet identifier and password and can be used to restore a wallet at https://blockchain.info/wallet/recover-wallet

- Blockchain.info will not be enforcing the new 54uBTC minimum output size. However the transaction creation routine has been altered to avoid creating any change outputs less than 0.01 BTC, using more outputs if necessary. This will avoid none standard transactions being created accidentally as defined by the new Bitcoin-Qt rule. The apps will also need adjusting.

- mBTC display can be enabled in account settings

- You can no longer add an alias without first verifying an email address.

The Chrome App needs translations.

Please add them 

Yes, and the world should be a better place

Which client signed the tx? I found something like this in log:

ERROR: Non-canonical signature: S value negative
ERROR: CScriptCheck() : d1b6f78247cfb448a7e9b00964d801fc02abb5f2c80423053634e01be26d6125 VerifySignature failed
ERROR: CTxMemPool::accept() : ConnectInputs failed d1b6f78247cfb448a7e9b00964d801fc02abb5f2c80423053634e01be26d6125

check it out:
http://blockchain.info/tx/d1b6f78247cfb448a7e9b00964d801fc02abb5f2c80423053634e01be26d6125?show_adv=true

sometimes other wrong type of signature appeared, all comes from blockchain.info

Edit: Add another one:
ERROR: Non-canonical signature: R value negative
ERROR: CScriptCheck() : e65f7625cc2f2f280e5af5b6c320c9e8a978000a70d61e399210890e435177c4 VerifySignature failed
ERROR: CTxMemPool::accept() : ConnectInputs failed e65f7625cc2f2f280e5af5b6c320c9e8a978000a70d61e399210890e435177c4

http://blockchain.info/tx/e65f7625cc2f2f280e5af5b6c320c9e8a978000a70d61e399210890e435177c4?show_adv=true

and a5ab5a894ac936771f716357c92660acedc5c35b915b9b5e599380c0a1252800 ...

She wrote her username into the transaction, so that i could see it in blockchain.info. As long as she have no donor it should be proof that its her address, so this forumuser paid this. At least i understand it now this way that only the real sender can put in a message. So it should be a proof as good as signing a message. Correct me if im wrong...

So you say it is unsecure? I asked in this thread and i was told its not possible to put your username to another users transaction. At least as long as you dont have access to his wallet. But if its this far a signed message cant help too anymore. So for now it looks like a proof to me. If you see a risk please explain where it lies.

Are you the owner of blockchain.info? If so can you say word about the description of transactions that can be done. I think, judging from what i was told, that the message can only be made from someone who has access to the sending address. So it delivers the same security like signing a message to an address. Because you have to have access to that address to be able to send money and to be able to sing messages/make a notice on a transaction. Thats right?

Hm... then i will demand a real proof. If there are possibilities to interfere its not good.

Thanks for clearing this up...