Proof-of-Time (PoT)

Proof-of-Time (PoT) is a broad label for techniques that let a computer prove that a certain amount of real time has elapsed, typically by performing a calculation that must be done in sequence and cannot be sped up much with extra hardware. The most studied tool for this is the verifiable delay function, which takes a fixed number of steps to compute but whose result can be checked quickly. Blockchains use such proofs for fair randomness and to pace block production. Solana's Proof-of-History is a related approach based on sequential hashing, and Chia combines proofs of space with proofs of time in its consensus. Some projects use the name for quite different designs, so meaning varies by source. On its own, proof of time does not secure a network; it is combined with staking, storage or other mechanisms. Also see Proof-of-Spacetime and consensus mechanism.