New here! I read this everywhere - "To change some data in a blockchain, the malicious user will have to recalculate hash for every block starting from that particular block".
My doubt is - Is that enough?
My understanding is that even if someone manages to recalculate all the hashes, the other nodes will still have the original, untampered blockchain. So the malicious user has to change those blocks for every single node (or at least 51% of the network). Is this correct?