Bitcoin self-custody company Casa said Tuesday it raised $21 million in a push to add financial identity functionality to its signature wallet product.

Casa builds what is known as a “self-custody” bitcoin (BTC) wallet that leaves users in control of their private keys. This differs from the custodial model employed by exchanges that take control of the crypto asset, and is favored by bitcoin diehards who live by the “be your own bank” mantra.

With the new round closed, Casa said it wants to make wallets more intertwined with their owner’s digital fingerprint. Its new “Casa API” will help businesses, such as Swan Bitcoin and Choice IRA, authenticate their customers’ financial identity when approving loans or making retirement investments, a press release said.

The round was led by Acrew Capital, with contributions from Positive Sum Ventures, Naval Ravikant and Scott Belsky, according to a press release. Last February, Casa raised $4 million in seed funding.

“Our investors will play a crucial role in driving the global self-sovereignty revolution in the years to come, ensuring we continue to drive the industry forward by delivering new solutions – like Casa API – that add to the richness, utility and, above all, security of Bitcoin,” said CEO Nick Neuman in a press release.

Read more: Bitcoin Startup Casa Raises $4M Led by Fidelity-Linked Avon Ventures