When refugees and migrants leave their homes behind, they may give up their possessions and livelihoods and often something else: their legal identity. They cross borders without proper documentation or their passports are lost or stolen along the way. German police said recently that 80% of Syrian refugees in that country didn’t have the right paperwork.

The lack of official IDs has compounding effects. Refugees can be shut out from social services or denied access to financial funds sitting in their home nations. Host governments have to issue new documents, which is expensive, takes time, and is open to fraud. And, for refugees, stuck in ad hoc accommodation, no identity means, in effect, that they are not only homeless, but, in a sense, anonymous.

This isn’t only a refugee problem. An estimated 1.5 billion people worldwide lack a legal identity–an issue the United Nations is pushing to address in its global development agenda. As part of the new Sustainable Development Goals agreed to by more than 150 world leaders last year, one aim is to “provide legal identity to all, including birth registration, by 2030.”

Co.Exist is running a series of stories this week about how we can create a refugee-ready, refugee-friendly world. You can read a collection of all the coverage here.

How might that happen? The United Nations already runs existing ID registers, like a biometric system for refugees in Senegal, and an iris-scanning system for Syrian refugees in Jordan. But John Edge, cofounder of the global initiative ID2020 initiative–a collaboration between UN agencies, NGOs, technology companies, and banks–says these are frequently disconnected from one another, making tracking people across borders difficult.

One of the most intriguing and radical ideas is a new kind of identity system based on blockchain technology, which could bring together disparate programs to create a new universal identity database.

An estimated 1.5 billion people worldwide lack a legal identity.

Blockchains–which first helped account and authenticate bitcoin cryptocurrency–are decentralized ledgers that track transactions of digital assets, whether it’s currency, stock and bonds, or identity details. The network is made up of a chain of computers, each of which have a copy of the ledger and can see if changes have occurred. Blockchains are thought to be secure because all computers must verify and approve each transaction as it takes place; a hacker couldn’t get to every single computer. On the identity blockchain, individuals would store their data in a sort of locker or escrow account, allowing people to access it on a need-to-know basis.

This has several advantages over the ways we traditionally think about identity. Most importantly, blockchain ID systems can reverse the normal way identity is established. Typically, identity is conferred by a national government, which certifies who we are and records this in a database. With blockchain technology, individuals create and store their own identity on networks of computers that no one person or entity controls, establishing a “self-sovereign identity.” In other words, refugees would no longer be dependent on home governments for their identity rights. People could reclaim their ID in whatever country they’re in without having to contact, say, the Assad regime in Syria. It could even allow for pseudonym IDs to protect activists living in repressive regimes or other vulnerable people.