Noise Protocol

Noise Protocol Framework 是一个握手协议构建器，可以裁剪出"双向认证 + 身份加密 + PFS + KCI 抗性"的最小盒子。 Noise_XX_25519_ChaChaPoly_SHA256 是其中最常用的三轮 mutual-auth 模式。

本专题以 bitchat（一个 BLE peer-to-peer 聊天 app）为载体，从「为什么 BLE 用不了 TLS」出发，逐步展示 e/s/ee/es/se/ss 记号、SymmetricState 双账本、XX 三轮握手、Split 分桨、Transport phase，最后回到 BLE GATT characteristic 的真实落地。