<oembed><type>rich</type><version>1.0</version><title>Big Barry Bitcoin wrote</title><author_name>Big Barry Bitcoin (npub1pk…tpxa6)</author_name><author_url>https://yabu.me/npub1pktmatjk0l8vn3jhfuwxaasjd65kn4ye9sce3egup7k993f8fg2q5tpxa6</author_url><provider_name>njump</provider_name><provider_url>https://yabu.me</provider_url><html>I was thinking about 2 things...&#xA;&#xA;1. The coldcard&#39;s co-signing feature https://coldcard.com/docs/coldcard-cosigning/&#xA;&#xA;2. Their satscard/tapsigner.&#xA;&#xA;In both cases, you could have the device generate a master key that you will never know. Only the device knows it (I might be wrong about the co-signing feature).&#xA;&#xA;With the tapsigner, you give it a chaincode, and that _theoretically_ gives you a key that you know Coinkite would never know.&#xA;&#xA;You can export the XPUB of m/0&#39; (I think) and it will have your chaincode in it.&#xA;&#xA;But... Since the rest of the derivation path is hardened in a typical key, you can&#39;t verify that the xpub for a typical wallet is derived using your chaincode. &#xA;&#xA;So....&#xA;&#xA;What if, just for that one key in a multisig setup, you don&#39;t use the typical derivation path so that you can confirm that it uses your chaincode, and since the change and index are not hardened, it still works as expected.&#xA;&#xA;Just trying to think about how you can Guarantee that neither the manufacturer or yourself knows the private key. </html></oembed>