add section Overview on the format of ws2p messages

rfc/0004_ws2p_v1.md

@@ -10,6 +10,7 @@ This document details the current specifications of WS2P v1 as they are already
   * [Endpoint format](#endpoint-format)
   * [Getting endpoints from other Duniter nodes](#getting-endpoints-from-other-duniter-nodes)
 * [Priority of WS2P outcoming connections](#priority-of-ws2p-outcoming-connections)
+* [Overview on the format of ws2p messages](#overview-on-the-format-of-ws2p-messages)
 * [Establishing a WS2P connection](#establishing-a-ws2p-connection)
 * [Rules for accepting an incoming connection](#rules-for-accepting-an-incoming-connection)
 * [HEAD messages](#head-messages)
@@ -84,6 +85,13 @@ If the key is a member: +1
 If the key is preferred/privileged: +2  
 If the key is the same as yourself: +4 (for multi-node)
 
+## Overview on the format of ws2p messages
+
+Most ws2p messages exist in two formats : 
+
+JSON: this is the format used to transmit the message through the websocket.  
+RAW: this is the format used to sign the message. Messages received in JSON must therefore be converted to raw format in order to verify the validity of their signature.
+
 ## Establishing a WS2P connection
 
 After sorting all WS2P endpoints according to the criteria described in the previous section,
@@ -100,7 +108,7 @@ for each connection attempt, the process is as follows:
 
 ### CONNECT message
 
-It's a JSON object :
+JSON format :
 
     {
         auth: 'CONNECT',
@@ -119,6 +127,8 @@ RAW format of the example message above : `WS2P:CONNECT:g1:D9D2zaJoWYWveii1JRYLV
 
 ### ACK message
 
+JSON format :
+
     {
         auth: 'ACK',
         pub: "D9D2zaJoWYWveii1JRYLVK3J4Z7ZH3QczoKrnQeiM6mx",
@@ -130,10 +140,13 @@ sig:  ed25519 signature of the RAW format message in base64.
     
 raw format : `WS2P:ACK:currency_name:pub:challenge`
 
-_*The challenge is the one we have written in our own CONNECT message._
+_*The challenge is the one we have written in our own CONNECT message. 
+The challenge is not retransmitted in json format of ACK messages because the remote node is supposed to already have this information._
 
 ### OK message
 
+JSON format :
+
     {
         auth: 'OK',
         sig
@@ -143,7 +156,8 @@ sig:  ed25519 signature of the RAW format message in base64.
     
 raw format : `WS2P:OK:currency_name:pub:challenge`
 
-_**Be careful**, this time the challenge is the one that **the remote node sent us** in **its own CONNECT message**._
+_**Be careful**, this time the challenge is the one that **the remote node sent us** in **its own CONNECT message**. 
+The challenge is not retransmitted in json format of OK messages because the remote node is supposed to already have this information._
 
 ## Rules for accepting an incoming connection