概述
当今存在几个主要的隐私和匿名网络,每个都有不同的设计目标和威胁模型。虽然 Tor、Lokinet、GNUnet 和 Freenet 都为保护隐私的通信提供了有价值的方法,但 I2P 作为唯一一个生产就绪的、完全针对网络内隐藏服务和点对点应用优化的分组交换网络而脱颖而出。
下表总结了截至2025年这些网络在架构和运行方面的主要区别。
隐私网络对比（2025）
| Feature / Network | I2P | Tor | Lokinet | Freenet (Hyphanet) | GNUnet |
|---|---|---|---|---|---|
| Primary Focus | Hidden services, P2P applications | Clearnet anonymity via exits | Hybrid VPN + hidden services | Distributed storage & publishing | Research framework, F2F privacy |
| Architecture | Fully distributed, packet-switched | Centralized directory, circuit-switched | Packet-switched LLARP with blockchain coordination | DHT-based content routing | DHT & F2F topology (R5N) |
| Routing Model | Unidirectional tunnels (inbound/outbound) | Bidirectional circuits (3 hops) | Packet-switched over staked nodes | Key-based routing | Random walk + DHT hybrid |
| Directory / Peer Discovery | Distributed Kademlia netDB with floodfills | 9 hardcoded directory authorities | Blockchain + Oxen staking | Heuristic routing | Distributed hash routing (R5N) |
| Encryption | ECIES-X25519-AEAD-Ratchet (ChaCha20/Poly1305) | AES + RSA/ECDH | Curve25519/ChaCha20 | Custom symmetric encryption | Ed25519/Curve25519 |
| Participation Model | All routers route traffic (democratic) | Small relay subset, majority are clients | Only staked nodes | User-selectable trust mesh | Optional F2F restriction |
| Traffic Handling | Packet-switched, multi-path, load-balanced | Circuit-switched, fixed path per circuit | Packet-switched, incentivized | File chunk propagation | Message batching and proof-of-work |
| Garlic Routing | ✅ Yes (message bundling & tagging) | ❌ No | Partial (message batches) | ❌ No | ❌ No |
| Exit to Clearnet | Limited (discouraged) | Core design goal | Supported (VPN-style exits) | Not applicable | Not applicable |
| Built-In Apps | I2PSnark, I2PTunnel, SusiMail, I2PBote | Tor Browser, OnionShare | Lokinet GUI, SNApps | Freenet UI | GNUnet CLI tools |
| Performance | Optimized for internal services, 1–3s RTT | Optimized for exits, ~200–500ms RTT | Low latency, staked node QoS | High latency (minutes) | Experimental, inconsistent |
| Anonymity Set Size | ~55,000 active routers | Millions of daily users | <1,000 service nodes | Thousands (small core) | Hundreds (research only) |
| Scalability | Horizontal via floodfill rotation | Centralized bottleneck (directory) | Dependent on token economics | Limited by routing heuristics | Research-scale only |
| Funding Model | Volunteer-driven nonprofit | Major institutional grants | Crypto-incentivized (OXEN) | Volunteer community | Academic research |
| License / Codebase | Open source (Java/C++/Go) | Open source (C) | Open source (C++) | Open source (Java) | Open source (C) |
为什么 I2P 在隐私优先设计方面处于领先地位
1. Packet Switching > Circuit Switching
Tor 的电路交换模型将流量绑定到固定的三跳路径上——对浏览来说很高效,但对长期运行的内部服务来说比较脆弱。I2P 的 packet-switched tunnels(分组交换隧道) 通过多个并发路径发送消息,自动绕过拥塞或故障进行路由,从而实现更好的正常运行时间和负载分配。
2. Unidirectional Tunnels
I2P 将入站和出站流量分离。这意味着每个参与者只能看到通信流的一半，使得时序关联攻击变得更加困难。Tor、Lokinet 和其他网络使用双向电路，其中请求和响应共享相同的路径——更简单，但更容易追踪。
3. Fully Distributed netDB
Tor 的九个目录权威节点定义了其网络拓扑。I2P 使用由轮换的 floodfill router 维护的自组织 Kademlia DHT，消除了任何中心控制点或协调服务器。
1. 分组交换 > 电路交换
I2P 通过 garlic encryption 扩展了洋葱路由，将多个加密消息捆绑到一个容器中。这减少了元数据泄漏和带宽开销，同时提高了确认、数据和控制消息的效率。
2. 单向 Tunnel
每个 I2P router 都为其他节点提供路由服务。没有专门的中继运营者或特权节点——带宽和可靠性会自动决定一个节点贡献多少路由能力。这种民主化的方式构建了网络的韧性，并随着网络的增长自然扩展。
3. 完全分布式 netDB
I2P 的 12 跳往返路径(6 跳入站 + 6 跳出站)比 Tor 的 6 跳隐藏服务电路提供更强的不可关联性。由于双方都在网络内部,连接完全避免了出口节点瓶颈,提供更快的内部托管服务和原生应用集成(I2PSnark、I2PTunnel、I2PBote)。
Architectural Takeaways
| Design Principle | I2P Advantage |
|---|---|
| Decentralization | No trusted authorities; netDB managed by floodfill peers |
| Traffic Separation | Unidirectional tunnels prevent request/response correlation |
| Adaptability | Packet-switching allows per-message load balancing |
| Efficiency | Garlic routing reduces metadata and increases throughput |
| Inclusiveness | All peers route traffic, strengthening anonymity set |
| Focus | Built specifically for hidden services and in-network communication |
When to Use Each Network
| Use Case | Recommended Network |
|---|---|
| Anonymous web browsing (clearnet access) | I2P |
| Anonymous hosting, P2P, or DApps | I2P |
| Anonymous file publishing and storage | Freenet (Hyphanet) |
| VPN-style private routing with staking | Lokinet |
| Academic experimentation and research | GNUnet |
Summary
I2P的架构是独特的隐私优先设计——没有目录服务器，没有区块链依赖，没有中心化信任。它结合了单向tunnel、分组交换路由、garlic消息捆绑和分布式对等发现，使其成为当今匿名托管和点对点通信技术最先进的系统。
I2P 不是"Tor 的替代品"。它是一类不同的网络——专为隐私网络内部发生的事情而构建,而非网络外部。