I6P — IPv6 Peer-to-Peer Protocol (Go)

I6P is a high-performance, IPv6-only P2P connectivity and transport layer. It is not a torrent client—it provides the foundation upon which P2P applications can be built.

Key Differentiators

Feature	Benefit
IPv6-only	End-to-end connectivity, no NAT traversal complexity
X25519 + ChaCha20-Poly1305	Fast, constant-time crypto without AES-NI
Symmetric Key Ratchet	Continuous forward secrecy per-message
LZ4 Compression	~4 GB/s compression speed on commodity CPUs
Merkle Tree Integrity	Verifiable chunks, resumable transfers
Reed-Solomon Erasure Coding	Recover lost packets without retransmission
Parallel Stream Pool	Saturate high-bandwidth links via QUIC multiplexing
Session Tickets	0-RTT resumption for returning peers
Batch Transmission	Reduced syscall overhead, efficient batching

Architecture

┌─────────────────────────────────────────────────────────────────┐
│                        Application Layer                        │
├─────────────────────────────────────────────────────────────────┤
│  transfer/  │  Chunker, Merkle, LZ4, Batching, Erasure, Pool    │
├─────────────────────────────────────────────────────────────────┤
│  session/   │  Handshake, Session, Tickets (0-RTT resumption)   │
├─────────────────────────────────────────────────────────────────┤
│  crypto/    │  X25519 ECDH, ChaCha20-Poly1305, HKDF, Ratchet    │
├─────────────────────────────────────────────────────────────────┤
│  protocol/  │  HELLO, PEER_INFO, DATA, ACK, CLOSE               │
├─────────────────────────────────────────────────────────────────┤
│  identity/  │  Ed25519 keys, PeerID = SHA-256(PublicKey)        │
├─────────────────────────────────────────────────────────────────┤
│  transport/ │  QUIC over UDP, TLS 1.3                           │
├─────────────────────────────────────────────────────────────────┤
│  discovery/ │  Pluggable (memory, DHT, mDNS)                    │
└─────────────────────────────────────────────────────────────────┘

Packages

Package	Description
i6p/identity	Ed25519 keys, PeerID, signing
i6p/protocol	Wire protocol, HELLO message, codec
i6p/crypto	X25519, ChaCha20-Poly1305 AEAD, HKDF
i6p/crypto/ratchet	Symmetric key ratchet for forward secrecy
i6p/session	Handshake, session management, tickets
i6p/transport/quic	QUIC transport with TLS 1.3
i6p/transfer	Chunking, Merkle trees, LZ4, batching, parallel streams
i6p/transfer/erasure	Reed-Solomon erasure coding
i6p/discovery	Discovery interfaces
i6p/discovery/memory	In-memory discovery (tests/examples)

Quick Start

# Run tests
go test ./...

# Run benchmarks
go test -bench=. ./...

# Run example
go run ./examples/basic

CI (GitHub Actions)

The ci workflow runs on push and pull requests:

• gofmt (format check)
• go test ./...
• govulncheck ./...
• golangci-lint

Docs

• Results: docs/RESULTS.md
• RFC (full protocol): docs/RFC.md
• Spec (Handshake/Messages/States/API): docs/SPEC.md

Performance

I6P is designed to maximize throughput on modern hardware:

• ChaCha20-Poly1305: ~3-5 GB/s encryption on modern CPUs
• LZ4 Compression: ~4 GB/s compression, ~8 GB/s decompression
• Reed-Solomon: Efficient SIMD-accelerated implementation
• Parallel Streams: Configurable stream pool to saturate bandwidth
• Zero-Copy Batching: Minimized memory allocations

Security Model

1. Transport Security: QUIC provides TLS 1.3 encryption
2. Identity Binding: Session handshake verifies PeerID = SHA-256(Ed25519_PublicKey)
3. Forward Secrecy: Ephemeral X25519 key exchange + symmetric ratchet
4. Integrity: Merkle proofs for every chunk
5. Session Resumption: Encrypted tickets for 0-RTT reconnection

Why I6P?

Traditional P2P	I6P
IPv4 + NAT traversal	IPv6 end-to-end
STUN/TURN/UPnP required	Direct connectivity
Complex hole punching	Globally routable addresses
Identity tied to IP	Cryptographic identity
Single stream	Parallel multiplexed streams
No erasure coding	Built-in loss recovery

Status

Production-ready baseline implementation. The discovery layer is intentionally modular; deployments will typically use DHT and/or mDNS.

License

MPL-2.0