2. Mostly Seedless Setup Overview for 3 of 5 Key Shield

 

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We recommend you go mostly "seedless" with your Casa keys. This means only recording a single 24-word seed phrase for your Key Shield setup, usually from your Ledger or Coldcard device.

What is a seed phrase?
 
Seed phrases are a physical copy of your private key. Before multisig, any loss of a key meant that funds were gone forever, so HW manufacturers work hard to ensure that users create backups.
 
The challenge of seed backups is they make security a lot more complicated. This is why we recommend you go mostly "seedless" with your Casa keys, only holding onto a single 24 word seed, usually from your Ledger or Coldcard device.

Why go mostly seedless?

We recommend a mostly seedless setup because a seed phrase can be compromised without your knowledge. Known problems or vulnerabilities can be fixed, but if you are not aware of a problem it can persist until it's too late. 

Keep in mind that your hardware wallet device can be secured with a PIN code but seed phrases cannot. 

But what if I lose or break my hardware wallet?

The seedless setup only works in a multisig setup because other keys exist to sign a transaction in the event that one of them is lost.

In the unlikely event that your hardware device is lost or damaged, you can still use the remaining keys in your multisig setup to spend funds.

That being said, if you have funds on a hardware wallet's stand-alone key, you DO need to retain the seed phrase, since that is your only backup should something happen to the hardware wallet. It's for this reason that we recommend that you use the hardware wallet device exclusively with Casa.

What if I don't want to go seedless?

While a seed phrase backup can be an additional point of compromise and is not protected with a PIN code like a hardware wallet is, it's ultimately up to you to decide if you want to retain the seed phrase or not.

There is no requirement that you "go seedless" when setting up multisig with Casa. 

Should something happen to your hardware wallet, retaining a copy of the seed phrase would allow you to restore the signing key on a new device. In this scenario, no changes would need to be made to your keyset.

How should I store my seed phrase?

We recommend storing your seed phrase in a sealed, tamper-proof evident bag. Punching the seed  phrase into a fire and water-resistant steel plate is also considered best practice. Then place the seed phrase and the corresponding hardware device together in a vault such as a safe deposit box.

What if I've already set up my hardware device with a seed phrase?

Our recommendation is to use a seedless multisig setup. If you've already written down and stored your seed phrase, and added it to Casa, we recommend that you rotate that device out of your keyset and replace it with a device that has no backup seed phrase. 

For more information about how Casa views seedless setup, check out our CTO Jameson Lopp's blog post on Casa's seedless security model

How can I protect my seed phrase from degrading over time?

Over time the paper seed phrase can degrade due to humidity or corrosion. There is also the possibility of an unlikely event such as a fire or flood to consider. To protect your seed phrase against these threats, a steel plate can be enlisted to record each of the seed phrase words. There are many plates to choose from; this article compares an array of products and considerations.

How does a steel plate work?

Casa recommends Blockplate and SeedSteel - steel plates with etched boxes that allow you to record each of the seed phrase words. We recommend using a steel punch to mark the letters, you can follow the guide at Blockplate.com.

Remember to hide any seed phrase you create in a sealed, tamper-evident bag to prevent it from being viewed.

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