[sebastiennight]

I don't even understand what an "unmodifiable blockchain" held by a single private entity could mean.

They

- have the data of yesterday

- have backups of the data of yesterday

- are going to write today's data on top of it to continue the chain

(insert magic here)

- somehow we are super sure, tomorrow, that today's data has not been tampered with

If somebody can shine some light on the magic part, I'm interested

[onraglanroad]

The point isn't that you can't add bad data: obviously you can.

The point is that if the hashes of the blocks are published, you can't later go back and tamper with that data.