graph TD
  A[Open Extension] --> B[Check Domain<br>Establish WebSocket Connection<br>Join Chatroom<br>Generate SHA-256 Hash]
  B --> C{Check for Stored Key Pair}
  C -->|Not Found| C0[Generate New RSA-2048 Key Pair<br>Export Keys as Base64<br>Generate Encryption Password Using PBKDF2<br>Encrypt Private Key with AES-GCM<br>Save to Chrome Storage]
    C0 --> D1
  C -->|Found| C1[Load Existing Key Pair<br>Generate Password Using Display Name<br>Decrypt Private Key with PBKDF2]
    C1 --> D{Decryption Successful?}
    D -->|Failed| C0
    D -->|Successful| D1[Share Public Key to Server]
      D1 --> E[Show Chat Interface<br>Fetch Online Users] 
      E --> F{Chat Mode}
        F -->|Group Chat| G[Plaintext Message]
        F -->|Private Chat| H[Request Recipient's Public Key]
          H --> I{Public Key Retrieved?}
            I -->|Failed| I0[Cannot Establish Encrypted Connection]
            I -->|Successful| J[Cache Recipient's Public Key<br>Start Encrypted Conversation<br>Encrypt Message with RSA-OAEP]
              J --> K[Send Encrypted Message to Server]
      E --> L[Leave Chatroom]
      L --> M[Clear Server-Side Data]
      M --> N[Retain Local Encrypted Data]

graph TD
  A[Receive Encrypted Message] --> B{Message Type}
  B -->|Group Message| C[Display Plaintext Directly]
    C --> D[Save Locally by Domain]
    D --> F[Update Chat History]
  B -->|Private Message| G[Decrypt Using Private Key]
    G --> H{Decryption Successful?}
      H -->|Successful| I[Display Decrypted Message]
        I --> D
      H -->|Failed| J[Show Decryption Failed]
        J --> D