IPFS and Filecoin

IPFS (InterPlanetary File System) is a content-addressed hypermedia protocol for the decentralized web. Filecoin extends it with a verifiable, decentralized storage marketplace.

IPFS

IPFS combines several foundational P2P concepts into a coherent stack:

Content addressing via CIDs: every piece of data is identified by its Content Identifier. Files are chunked into blocks, organized into a Merkle DAG (UnixFS), and the root CID identifies the whole file.

Bitswap: a block exchange protocol where peers request blocks by CID and track per-peer ledgers of bytes sent/received. This implements swarming for content-addressed blocks.

Kademlia DHT: the Amino DHT, one of the largest Kademlia networks, used for provider record publication and peer routing.

IPNS: mutable pointers over immutable data; a signed record in the DHT maps a public identity key to a CID.

Pinning: explicit durable retention. Pinning services (Pinata, web3.storage) provide persistent availability.

Gateways: HTTP-to-IPFS bridges for browser access. Trustless gateways serve verified blocks rather than requiring trust in the gateway operator.

CAR files: Content Addressable aRchive format for bundling blocks for efficient transport and backup.

IPFS uses libp2p for all networking.

Filecoin

Filecoin adds economic incentives to IPFS:

Storage market: clients pay storage providers (miners) FIL tokens to store data for a specified duration via on-chain deals.

Proof-of-Replication (PoRep): a cryptographic proof that the provider has created a unique physical copy of the data.

Proof-of-Spacetime (PoSt): periodic proofs that the data is still being stored, submitted to the blockchain.

Retrieval market: a separate market for serving data, incentivizing bandwidth alongside storage.

FVM (Filecoin Virtual Machine): smart contracts on Filecoin for programmable storage deals, data DAOs, and cross-chain bridges.

Filecoin demonstrates that Storage and Distribution can be backed by verifiable economic commitments rather than just goodwill or bilateral tit-for-tat.

GraphSync

An alternative to Bitswap for transferring large DAG subsets efficiently:

The requester specifies a selector (a DAG traversal query describing what to fetch).

The responder streams matching blocks in a single round trip.

Much more efficient than Bitswap for large directories, datasets, and Filecoin retrieval.

How IPFS/Filecoin Connects to Everything Else

IPFS is the flagship application of Content Addressing, Overlay Networks, and libp2p. Identity is used for IPNS, UCAN-based authorization, and Filecoin miner identity. Security considerations include DHT poisoning, content availability attacks, and gateway trust. Privacy is a concern: requesting a CID from the DHT reveals your interest. Compliance applies to gateway and pinning service operators. Testing uses Testground for large-scale network simulation.