Signal

• signalapp
  • Signal-Server
    • AGPLv3, Java
  • Signal-Android
    • GPLv3, Java, Kotlin
  • Signal-iOS
    • AGPLv3, Swift, ObjC
  • Signal-Desktop
    • AGPLv3, Typescript, Electron
  • libsignal
    • AGPLv3, Rust, Java, Switf, TypeScript
• Signal Protocol
  • E2E 加密
  • 群组消息单独加密
  • Double Ratchet
  • used by WhatsApp, Facebook Messenger, Google Allo, Signal
• Double Ratchet
  • Diffie-Hellman key exchange
  • out-of-order messages, message resynchronization, message authentication
  • used by Signal, WhatsApp, Wire

Server

• Signal-Server
  • AGPLv3, Java
  • Dropwizard, resilience4j, curve25519-java, Bouncy Castle, Jedis, Lettuce, Liquibase, libphonenumber
  • grpc, websocket, graphql
  • mockito, wiremock, assertj
  • com.eatthepath.pushy
  • Redis Pub/Sub
  • Redis Lua 定义脚本
  • Cache - DynamoDB + Redis
• 旧的 DB messagedb.xml
• 参考
  • What I've learned from Signal server source code
    • resources/lua/insert_item.lua
      • messageId=counter++
      • ZADD Queue messageId Message
      • HSET Meta guid messageId
      • EXPIRE Queue 90 days
      • EXPIRE Meta 90 days

proto

• signalapp/Signal-Server/service/src/main/proto

enum PubSubType {
  UNKNOWN   = 0;
  QUERY_DB  = 1;
  DELIVER   = 2;
  KEEPALIVE = 3;
  CLOSE     = 4;
  CONNECTED = 5;
}