IPFS

• specs: https://github.com/ipfs/specs

IPFS is a P2P protocol

Stack

• IPLD
• BitSwap
• Distributed Hash Table

The DHT

Read more at https://blog.ipfs.io/2020-07-20-dht-deep-dive/.

• IPFS uses a custom version of Kademlia (DHT).
  • Address space: 0 to 2^256-1
  • Metric: SHA256(PeerID) –> 0 to 2^256-1
  • Projection: SHA256(RecordKey)
• The DHT stores 3 types of key-value pairings:
  • Provider Records: map identifiers (i.e., multihashes) to peers that adversited they have and are willing to provide the content.
    • Used by IPFS to find content
    • Used by IPNS over PubSub to find other members of the pubsub topic
  • IPNS Records: map IPNS keys to IPNS records
    • Used by IPNS
  • Peer Records: map peerID to a set of multiaddresses at which the peer may be reached
    • Used by IPFS when we know of a peer wwith content, but don’t know its address
    • Used for manual connectiong (ipfs swarm connect…)
  • KEEP READING: https://blog.ipfs.io/2020-07-20-dht-deep-dive/#kademlia-and-undialable-peers

Compared to BitTorrent

• Does not privilege nodes.
• Blocks are not tied to a specific torrent.

Compared to DAT

• TODO