The Secure Proof of Stake protocol (SPoS) uses a reputation-verification platform to solve the centralization, efficiency, and security problems that afflict existing blockchain consensus protocols. At heart, a secure proof of stake protocol follows naturally from a secure decentralized autonomous system for validating the reputation of anonymous users. SPoS has several advantageous features over previous PoS protocols. SPoS enables on-chain governance to decide issues such as standards for block creation, policing, and scaling. All protocol upgrades are handled swiftly, decisively, openly, and stably, through the weighted democracy of reputation-staked decision making. Because nodes no longer hash mine but rather check the validity of blocks and vote, SPoS is more efficient than proof-of-work consensus. This paper explains the SPoS protocol and how it maintains decentralization, efficiency, liveness, swift finality, and anonymity, while addressing the security issues of Byzantine faults, the various 51% attacks, stake grinding, the tragedy of the commons, DoS attacks, censorship, liveness faults, Sybil attacks, tyranny of the majority, and soft protocol upgrades
