Verifiable Delay Functions (VDFs) are cryptographic primitives that play an essential role in enhancing the security and [[finality]] of a blockchain [[consensus mechanism]]. To accomplish this, they employ a proof-of-elapsed-time mechanism that is resistant to parallel computing advantages. VDFs were first introduced in [[Verifiable Delay Functions.pdf|a 2018 paper (PDF)]] by Dan Boneh, Joseph Bonneau, Benedikt Bünz, and Ben Fisch from Stanford University. The concept was developed as part of their ongoing research into cryptographic protocols. A VDF requires a specified amount of sequential computation to generate an output from given input but allows anyone else to verify the correctness of this output. In other words, it takes time 't' to compute but can be verified quickly once computed, making verification relatively easy but secure. Here is how a VDF better serves cryptographic systems: 1. **Finality**: VDFs help achieve [[Finality#Probabilistic Finality|probabilistic finality]] by introducing delays into block production or validation process. This delay ensures that all nodes have sufficient time to agree on the current state before moving forward. 2. **Security**: By requiring a certain amount of real-time work for generating outputs and making them verifiable easily and quickly by others, VDFs improve [[Sybil Resistance]], reducing attacks where users create multiple identities to influence the network. 3. **[[Immutability]]**: The use of VDFs helps maintain immutability as changing any information would require recomputing the function which is computationally expensive and time-consuming. 4. **Consensus**: In [[Proof of Stake]] (PoS) systems like Ethereum 2.0, randomness plays a crucial role in selecting [[validators]] for creating blocks or validating transactions; however achieving unbiased randomness is challenging due its predictability leading attackers gaining unfair advantage over honest participants . Here's where VDF comes into picture providing unpredictable randomness ensuring fair validator selection thus aiding consensus mechanism. >[!example] Implementations >Ethereum 2.0 plans on using VDFs as part of their PoS protocol called "Ethash". It will be used alongside RANDAO (a DAO generating random numbers), combining unpredictability from RANDAO and unbiasedness from VDFs to generate a random beacon for validator selection. > >Another implementation is in Filecoin, where VDFs are used as part of their Proof-of-Replication (PoRep) and Proof-of-Spacetime (PoSt) protocols. These protocols ensure that storage miners prove they're storing the data they committed to over time.