Quotes About Cryptographically

Fundamentally, blockchains are software protocols that allow multiple parties to operate under shared assumptions and data without trusting each other. These data can be anything, such as location and destination information of items in a supply chain or account balances of a token. Updates are packaged into "blocks" and are "chained" together cryptographically to allow an audit of the prior history – hence the name.

The ledger, the distributed database - it's called a Blockchain - is held in the cloud by all the parties involved. It can't be broken by any of them. It's cryptographically too strong. You would have to compromise the entire network to take over Bitcoin.