Proof of Retrievability

Proof of Retrievability (PoR) is a type of consensus algorithm used in distributed systems, particularly in cloud storage. The algorithm ensures that data stored in a cloud server can be retrieved at any time, verifying its integrity and availability.

PoR is different from other consensus algorithms because it's not based on computing power or stake, but on the ability to retrieve data. It works by having the user store a small proof of the data's retrievability, which can then be verified by the network.

The process starts with the user dividing their data into small pieces and sending them to the cloud server. The server stores the data, computes a hash of each piece, and sends the hashes back to the user. The user then combines the hashes and generates a single proof that can be used to retrieve the data.

To ensure the proof's correctness, PoR uses a challenge-response protocol. The user sends a random challenge to the server, which responds with the requested data piece and its hash. The user then checks the hash against the one received earlier, ensuring the data's integrity.

PoR is a lightweight algorithm that requires minimal resources, making it an efficient and cost-effective solution for cloud storage. It's also secure because it provides a high degree of assurance that the data is retrievable and hasn't been tampered with.

In summary, PoR is a consensus algorithm that ensures the retrievability of data stored in a cloud server. It works by dividing the data into small pieces, generating a proof of retrievability, and using a challenge-response protocol to verify the data's integrity. PoR is a lightweight and cost-effective solution for cloud storage and provides a high degree of assurance that the data is available and secure.