dkd 0.2.3

A common message module

Dao Ke Dao (道可道) -- Message Module

This document introduces a common Message Module for decentralized instant messaging.

Copyright © 2018 Albert Moky

• Envelope
  • Sender
  • Receiver
  • Time
• Content
  • Type
  • Serial Number
• Message
  • Instant Message
  • Secure Message
  • Reliable Message

0. Envelope

Message Envelope

/* example */
{
    sender   : "moki@4WDfe3zZ4T7opFSi3iDAKiuTnUHjxmXekk",
    receiver : "hulk@4YeVEN3aUnvC1DNUufCq1bs9zoBSJTzVEj",
    time     : 1545405083
}

1. Content

/* example */
{
    type     : 0x01,      // message type
    sn       : 412968873, // serial number (message ID in conversation)

    text     : "Hey guy!"
}

Message Content Type

enum {
    DIMMessageType_Unknown = 0x00,

    DIMMessageType_Text    = 0x01,

    DIMMessageType_File    = 0x10,
    DIMMessageType_Image   = 0x12, // photo
    DIMMessageType_Audio   = 0x14, // voice
    DIMMessageType_Video   = 0x16,

    DIMMessageType_Page    = 0x20, // web page

    // quote an exists message and reply it with text
    DIMMessageType_Quote   = 0x37,

    // system command
    DIMMessageType_Command = 0x88,

    // top-secret message forwarded by proxy(account or station)
    DIMMessageType_Forward = 0xFF
};

2. Message

When the user want to send out a message, the client needs TWO steps before sending it:

1. Encrypt the Instant Message to Secure Message;
2. Sign the Secure Message to Reliable Message.

Accordingly, when the client received a message, it needs TWO steps to extract the content:

1. Verify the Reliable Message to Secure Message;
2. Decrypt the Secure Message to Instant Message.

Instant Message

/* example */
{
    //-------- head (envelope) --------
    sender   : "moki@4WDfe3zZ4T7opFSi3iDAKiuTnUHjxmXekk",
    receiver : "hulk@4YeVEN3aUnvC1DNUufCq1bs9zoBSJTzVEj",
    time     : 1545405083,

    //-------- body (content) ---------
    content  : {
        type : 0x01,      // message type
        sn   : 412968873, // serial number (ID)
        text : "Hey guy!"
    }
}

content -> JsON string: {"sn":412968873,"text":"Hey guy!","type":1}

Secure Message

/**
 *  Algorithm:
 *      string = json(content);
 *      PW     = random();
 *      data   = encrpyt(string, PW);      // Symmetric
 *      key    = encrypt(PW, receiver.PK); // Asymmetric
 */
{
    //-------- head (envelope) --------
    sender   : "moki@4WDfe3zZ4T7opFSi3iDAKiuTnUHjxmXekk",
    receiver : "hulk@4YeVEN3aUnvC1DNUufCq1bs9zoBSJTzVEj",
    time     : 1545405083,

    //-------- body (content) ---------
    data     : "9cjCKG99ULCCxbL2mkc/MgF1saeRqJaCc+S12+HCqmsuF7TWK61EwTQWZSKskUeF",
    key      : "WH/wAcu+HfpaLq+vRblNnYufkyjTm4FgYyzW3wBDeRtXs1TeDmRxKVu7nQI/sdIALGLXrY+O5mlRfhU8f8TuIBilZUlX/eIUpL4uSDYKVLaRG9pOcrCHKevjUpId9x/8KBEiMIL5LB0Vo7sKrvrqosCnIgNfHbXMKvMzwcqZEU8="
}

Reliable Message

/**
 *  Algorithm:
 *      signature = sign(data, sender.SK);
 */
{
    //-------- head (envelope) --------
    sender   : "moki@4WDfe3zZ4T7opFSi3iDAKiuTnUHjxmXekk",
    receiver : "hulk@4YeVEN3aUnvC1DNUufCq1bs9zoBSJTzVEj",
    time     : 1545405083,

    //-------- body (content) ---------
    data      : "9cjCKG99ULCCxbL2mkc/MgF1saeRqJaCc+S12+HCqmsuF7TWK61EwTQWZSKskUeF",
    key       : "WH/wAcu+HfpaLq+vRblNnYufkyjTm4FgYyzW3wBDeRtXs1TeDmRxKVu7nQI/sdIALGLXrY+O5mlRfhU8f8TuIBilZUlX/eIUpL4uSDYKVLaRG9pOcrCHKevjUpId9x/8KBEiMIL5LB0Vo7sKrvrqosCnIgNfHbXMKvMzwcqZEU8=",
    signature : "Yo+hchWsQlWHtc8iMGS7jpn/i9pOLNq0E3dTNsx80QdBboTLeKoJYAg/lI+kZL+g7oWJYpD4qKemOwzI+9pxdMuZmPycG+0/VM3HVSMcguEOqOH9SElp/fYVnm4aSjAJk2vBpARzMT0aRNp/jTFLawmMDuIlgWhBfXvH7bT7rDI="
}

(All data encode with BASE64 algorithm as default)