Quote from: fluffypony on September 16, 2014, 02:09:00 PM

Quote from: Odalv on September 16, 2014, 12:55:06 PM

1. Good thing for hacker(one member of group) to wipe out your wallet by modifying orginal transaction and send all your XMR to his address.

Not possible. Once a transaction is mined its permanent. If you mean after broadcast and before its mined, then you need to follow the maths in the whitepaper. Individual *inputs* are ring-signed, not the whole tx. You can't change an input without mucking up the signature for the whole transaction.

Quote from: Odalv on September 16, 2014, 12:55:06 PM

2. How can you guarantee, there is no miner or passive listener who is building unobscured private blockchain and sell this data ? (why not to store internal data unobscured when it takes 6 times less space than monero blockchain)

How? In order for them to do this they'd need to own a massive portion of the utxoset. Maybe you need to read our research bulletin on chain reactions and traceability in the CryptoNote protocol, as it explains exactly why this is impossible without a huge amount of utxos under your private control: http://lab.monero.cc/pubs/MRL-0001.pdf

Quote from: Odalv on September 16, 2014, 12:55:06 PM

3. How you can prove that you really paid or even did not want to pay.to hacker :-)

Because even though the inputs are ring signed (and thus you can (ostensibly) never know if an input was genuine or merely part of a group signature) the outputs are signed by you and you alone. Thus, verification is trivial - you merely need to reveal the one-time key for that transaction to verify it.

Quote from: Odalv on September 16, 2014, 12:55:06 PM

Once I know your PUBLIC key I can add you to my GROUP (adding my and your public key together). Then create ring signature and no one knows who signed message you or me. Then I can fork blockchain !!! (maybe even from genesis block)

Again, you're conflating ring-signed inputs with individually-signed outputs. The trick here is the combination of stealth addresses and ring signatures, not one or the other. I'd suggest you start with the whitepaper and fully grok the maths behind it as a first step towards understanding.

lol, I still don't get it.
Who or what prevents me from ring-signing your input and send your money to my address(output).