Does my data go on-chain?

Does my data go on-chain?

No. Your data stays off-chain.

What goes on-chain is a cryptographic fingerprint of the data, called a hash (see What is a cryptographic hash?). A hash is a short, fixed-length string. It can't be reversed to recover the data, and it reveals nothing about what's inside: no names, no balances, no account numbers, no loan terms.

The fingerprint does one job. It lets anyone holding the original data confirm that it hasn't changed since the fingerprint was recorded. If even one character changes, the fingerprint won't match.

For large datasets such as loan tapes, records are fingerprinted individually and combined into a single root (see What is a Merkle tree?). That makes it possible to prove that one specific record is included without showing any of the others.

Who can see the underlying data is set by the agreements between the parties, the same way it would be without a blockchain. Investors see what they're entitled to see. Borrower-level data stays with the parties who need it to service and monitor the loans.

There are also good reasons not to put personal data on a public blockchain: it can't be deleted, and in most jurisdictions publishing it would breach data protection law. See Hash-then-anchor for the full explanation.