Isolation of witness not only bring the expansion, but also let more security hardware Wallet

Isolation of witness not only bring the expansion, but also let more security hardware Wallet

BitcoinCore last week released the latest version of the software 0.13.1, which includes a version of the isolated witness soft bifurcation. If the signal of this proposal was the vast majority of miners, perhaps the fastest isolated witness — in December will be able to activate the activation in the bitcoin network will. This soft bifurcation will bring a number of benefits, including improve the block size limits and the ductility of the repair.

However, there is a little-known trade advantage is input – bitcoin send – will for the first time by the user to encrypt the signature: This is a small change, but according to LedgerCTONicolasBacca, “this change to repair one of the biggest problems facing the hardware bitcoin wallet.”


All bitcoin transactions are from the “input (input)” to “output (output)” to send bitcoin, bitcoin is sending the specified input address, and output to receive address.

Of course, all the input and output is at least equal. The sender can not create bitcoin.

However, in fact, in general, bitcoin input than output slightly more. This difference is the fee. So if all the input is 1BTC, then all the output may be 0.999BTC, who handle the deal, people can get paid 0.001BTC.

But there is a strange. Although the output includes the amount of input is not clear, but. This is not a problem, because every input are dependent on the prior transaction, so bitcoin wallet can be checked by the blockchain to check specific input number.

However, hardware wallet exception, explained to BitcoinMagazine Bacca:

“Hardware wallet does not store the entire block chain, also do not have direct access to the bitcoin network. On the contrary, they are connected through the software to collect transaction history. For example, they connect to the Internet through running on the computer through the network or purse, wallet.”

In many cases, this is not what the problem. The hardware generates a transaction wallet, to send a certain amount of bitcoins. If you really want to send to the bitcoin address, he could sign a deal. To send input funds is not a risk.

However, this may cause the risks of “fee attack”, JonasSchelli BitcoinCore and DigitalBitbox developers told BitcoinMagazine.

“For example, if your computer is trojan break Troy. When you send the money from the hardware wallet, this Trojan will increase the amount of input, or additional input, but did not inform the user. Through the hardware wallet, and then confirm the user check the output, and then sign the transaction. But the user does not know the actual amount of input is higher than the transaction needs; even all bitcoin wallet in the hardware store may be sent when the user does not know the circumstances, then as a huge fee allocated to miners.”

Although it might not be possible, but the risk of a serious blow to one of the most important use of hardware wallet. After all, the hardware wallet lies in these devices even if not connected with the safety of the computer cannot be attacked.

Isolation of witness

Strategies for this “fee” attack does exist. Before a transaction can obtain the blockchain hardware wallet connected by software, the output into a hash, then compare the input hash and new transactions.

However, the Trezor architect Marek “Slush” Palatinus explained,

“These solutions are extremely complex and slow.”

Due to the limited hardware wallet computing resources, in some cases, they are even not feasible.

Palatinus said:

“Including the input or output of a large number of transactions, such as the mineral pool spending, may take an hour to calculate.”

Isolated witness to provide a better solution.

Isolation of witnesses will move to an encrypted signature transaction “additional” part of “witness”. It is not important to the hardware wallet. But as the signature data is moved, and change the wallet to read data, BitcoinCore developers decided to slightly change the signature generation process.

Specifically, is the input signature — though still not part of the transaction itself. To some extent, these inputs become a part of the encrypted signature “. For example, hardware wallet users will only the specific amount of bitcoins to send the signature — without the need to go through a complex and slow process, and avoid the risk of sending too much money. (if a Trojan Troy tried to change the input, after the signature of the deal will be bitcoin node invalid.)

If the witness isolation is activated, so you can easily upgrade all existing hardware wallet to use this option. Ledger has been on the Ledger code base has been upgraded, at the same time, if the isolation to witness the soft forked is activated, then Trezor and DigitalBitbox will also be ready to integrate.

Palatinus said:

Isolation of witness not only brought expansion.”

“Bitcoin still exists some other problems, isolation witness has opened a new door for potential is currently not possible applications and use cases. For those who believe that only the larger block size can save the bitcoin exchange rate, for those who will decide whether it should be witnessed by isolating the miners, it’s important to understand.”

Leave a Reply

Your email address will not be published. Required fields are marked *