Proof-of-Access (PoAc) is a consensus mechanism used by Arweave to ensure the permanent storage of data by requiring miners to retrieve and use an old block from the network's history before adding a new block.
Proof-of-Access is a unique consensus mechanism used by the Arweave network to ensure that data stored on its platform is saved permanently and remains accessible at all times.
When a miner wants to add a new block to the Arweave blockchain, they must first "access" or retrieve a random old block from the network’s history. This old block serves as proof that storage nodes still have copies of the data, no matter how old it is. After retrieving the old block, the miner uses information from that block, along with new transactions to create a new block. Other nodes on the network verify that the miner has correctly accessed the old block and used its data to create the new block.
By routinely requiring miners to access old blocks, the network regularly checks on its stored data. Since each new block is connected to a randomly selected old block, altering any stored data would require not just changing a single block but many blocks throughout the chain. This protects the data from being tampered with.
Proof-of-Access also encourages miners to maintain copies of the network’s data to prevent data loss even if some parts of the network fail or are compromised. This ensures that all data is well-maintained, easy to find, and safe from damage no matter what.
