It seems that data brokering is about moving data from place to place. The data is public but you want to ensure that it hasn't been changed from its original source.
This is exactly what blockchain ledgers are meant to do. As a starship moves from system to system, new data brokers can attach data to the data store and digitally sign it so that it's essentially tamper-proof.
You might manage to forge an entry yourself, but because other ships carry the same data, eventually they'll show up and there will be a discrepancy, and a blockchain "vote" will occur and resolve the lie.
This is exactly what blockchain ledgers are meant to do. As a starship moves from system to system, new data brokers can attach data to the data store and digitally sign it so that it's essentially tamper-proof.
You might manage to forge an entry yourself, but because other ships carry the same data, eventually they'll show up and there will be a discrepancy, and a blockchain "vote" will occur and resolve the lie.