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The new features are available today for Casa gold members (priced at $25 a month) but will also be rolling out to all Casa users next week, according to the company’s announcement yesterday.
The update includes an improved “2-of-3” multisig setup that now allows the use of up to two hardware keys. In short, a multisig (multi-signature) set up simply means that more permissions are required to move the bitcoins stored in a wallet to a new address.
Typically, most popular wallets that are available today (both mobile and hardware) have a basic 1-of-1 setup—meaning that only one key is required to sign a transaction that moves bitcoins from one wallet to another. Advanced setups with multisig can exponentially increase the security of a Bitcoin wallet by distributing the power to make transactions between a number of keys that are stored across various locations and device types.
Prior to the upgrade, Casa had enabled the use of a “2-of-3 multisig” setup—but only using one hardware key. When enabled, this feature made it so users needed at least two cryptographic signatures to make a transaction on the Bitcoin network. Those signatures could come from a combination of a hardware wallet (like the popular Trezor or Ledger), Casa’s mobile wallet, and finally a third key (if needed) that is securely held by Casa. The upgrade now makes the wallet even harder to compromise.
The firm has already previously deployed a 3-of-5 multisig setup for its users. This can include the use of up to three hardware keys, with the other keys coming from mobile wallets or keys held by Casa.
Casa noted in its announcement that its “full Key Shield 3-of-5 multisig is built for storing $100k to $1MM+ of Bitcoin,” though this latest upgrade helps improve security for storing lower amounts of Bitcoin.
The wallet's capabilities, though, could potentially help position Casa as part of a custody solution for clients who would like to jointly have control over Bitcoin funds. With the possibility to now use two hardware keys, a pair of partners could each retain control of one hardware key each.
This would mean that each keyholder would be safe in the knowledge that they could not solely be responsible for a breach of funds, while also knowing that only they together with other keyholders have the ability to move bitcoins out of their wallets.
Editor's note: A previous version of this article incorrectly reported that Casa's latest security upgrade enabled the secure storage of large amounts of Bitcoin. Casa has clarified that this particular feature had already been deployed. We regret the error.