Unlike centralized databases, blockchain protocols feature unprecedented levels of network security, particularly among permissionless blockchains. In most cases, security is achieved by the unique combination of decentralized network participants and energy-consuming or restrictive consensus mechanisms needed to verify transactions and provide a disincentive for malicious actors in the process.

Tampering with a permissionless blockchain protocol, by either attempting to alter past transactions or double-spend in the present, would require an enormous amount of computing power and an ability to simultaneously control 51% of the distributed network nodes around the world. These factors together give blockchain technology its unique and powerful security features.