<oembed><type>rich</type><version>1.0</version><author_name>npub1lf5jdpupmcelz945y09tzawew6pqs5wkkp6dppeujgxxnqltgufsmzuul6</author_name><author_url>https://nostr.ae/npub1lf5jdpupmcelz945y09tzawew6pqs5wkkp6dppeujgxxnqltgufsmzuul6</author_url><provider_name>njump</provider_name><provider_url>https://nostr.ae</provider_url><html>📅 Original date posted:2016-08-04&#xA;📝 Original message:&#34;This is already possible. Just nLockTime your withdrawls for some future&#xA;block. Don&#39;t sign any transaction that isn&#39;t nLockTime&#39;d at least N blocks&#xA;beyond the present tip.&#34;&#xA;&#xA;This would have prevented the Bitfinex hack if BitGo did this, but it&#xA;wouldn&#39;t have helped if the Bitfinex offline key had been compromised&#xA;instead of BitGo doing the 2nd sig.  In the BFX hack the TXNs were signed&#xA;by Bitfinex&#39;s hot key and BitGo&#39;s key, they required 2 of 2.&#xA;&#xA;If I&#39;m understanding correctly, what Matthew is proposing is a new type of&#xA;UTXO that is only valid to be spent as an nLockTime transaction and can be&#xA;reversed by some sort of RBF-type transaction within that time period, I&#xA;believe.&#xA;&#xA;But I don&#39;t think this will work. What do you do if the keys are&#xA;compromised?  What&#39;s to stop the attacker from locking the coins up&#xA;indefinitely by repeatedly broadcasting a refund transaction each time you&#xA;try to spend to an uncompromised address?&#xA;&#xA;You&#39;d need a third distinct key required for the refund TXN that&#39;s separate&#xA;from the keys used to sign the initial nLockTime TXN.  And the refund TXN&#xA;would need to be able to go to a new address entirely.&#xA;&#xA;On Aug 3, 2016 11:28 PM, &#34;Luke Dashjr via bitcoin-dev&#34; &lt;&#xA;bitcoin-dev at lists.linuxfoundation.org&gt; wrote:&#xA;&#xA;&gt; On Wednesday, August 03, 2016 6:16:20 PM Matthew Roberts via bitcoin-dev&#xA;&gt; wrote:&#xA;&gt; &gt; In light of the recent hack: what does everyone think of the idea of&#xA;&gt; &gt; creating a new address type that has a reversal key and settlement layer&#xA;&gt; &gt; that can be used to revoke transactions?&#xA;&gt;&#xA;&gt; This isn&#39;t something that makes sense at the address, since it represents&#xA;&gt; the&#xA;&gt; recipient and not the sender. Transactions are not sent from addresses&#xA;&gt; ever.&#xA;&gt;&#xA;&gt; &gt; You could specify so that transactions &#34;sent&#34; from these addresses must&#xA;&gt; &gt; receive N confirmations before they can&#39;t be revoked, after which the&#xA;&gt; &gt; transaction is &#34;settled&#34; and the coins become redeemable from their&#xA;&gt; &gt; destination output. A settlement phase would also mean that a&#xA;&gt; transaction&#39;s&#xA;&gt; &gt; progress was publicly visible so transparent fraud prevention and&#xA;&gt; auditing&#xA;&gt; &gt; would become possible by anyone.&#xA;&gt;&#xA;&gt; This is already possible. Just nLockTime your withdrawls for some future&#xA;&gt; block. Don&#39;t sign any transaction that isn&#39;t nLockTime&#39;d at least N blocks&#xA;&gt; beyond the present tip.&#xA;&gt;&#xA;&gt; Luke&#xA;&gt; _______________________________________________&#xA;&gt; bitcoin-dev mailing list&#xA;&gt; bitcoin-dev at lists.linuxfoundation.org&#xA;&gt; https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev&#xA;&gt;&#xA;-------------- next part --------------&#xA;An HTML attachment was scrubbed...&#xA;URL: &lt;http://lists.linuxfoundation.org/pipermail/bitcoin-dev/attachments/20160803/c004566c/attachment.html&gt;</html></oembed>