How to send 1-N signalling or broadcast messages on Whisper?

Question

From Whisper wiki:

Low-latency, 1-1 or 1-N signalling messages.

Shh.post(self, message:) and Whisper Usage / shh.post

Creates a whisper message and injects it into the network for distribution.

Example usage of web3.shh.post, for more details please see this answer:

web3.shh.post({
  pubKey: 'PUBLIC_KEY_OF_THE_RECEIVER',
  ttl: 3600,
  topic: '0x07678231',
  powTarget: 2.01,
  powTime: 2,
  payload: web3.fromAscii("Hello there!")
  });

---

When I remove pubKey from web3.shh.post as arguments; it says: Error: specify either a symmetric or an asymmetric key.

shh.post({ "topic": t, "payload": p }); No signature, no encryption: Anonymous broadcast; a bit like an anonymous subject-filtered twitter feed.

[Q] Since web3.shh.post()requires us to provide single public key of the receiver; is it possible to send 1-N or broadcast message using whisper protocol? If yes, how?

Answer 1

I would recommended to use this documentation : https://github.com/ethereum/go-ethereum/wiki/Whisper

Whisper usage

your posted links are outdated and moreover are for Whisper v 2.0

Answer: It's possible 1:N message if you provide identical symKey for all recipients.

P.S. My posted links are for Whisper 5.0 , current version of Whisper is 6.0 but but the API for v6 is almost identical to v5 anyway.

---

On node-1's geth-client:

generatedSymKey=shh.generateSymKeyFromPassword("hello");    
symKey=shh.getSymKey(generatedSymKey)    
symKeyID=shh.addSymKey(symKey) //ex: "d5212e736703afbb21246e8acd192e4345ea910398544d765ed6b49f0ec524b5"
filter = web3.shh.newMessageFilter(
        {symKeyID:symKeyID, topic: '0x07678231'}, 
        function(err, res) {console.log(web3.toUtf8(res.payload))});

On node-2's geth-client:

generatedSymKey=shh.generateSymKeyFromPassword("hello")    
symKey=shh.getSymKey(generatedSymKey)    
symKeyID=shh.addSymKey(symKey) //ex: "c4c4cecf6ad9499c2386b8ce6416f44684e042e491726b38315646c0b4afadc6"
filter = web3.shh.newMessageFilter(
        {symKeyID:symKeyID, topic: '0x07678231'}, 
        function(err, res) {console.log(web3.toUtf8(res.payload))});

---

Than, sending message on another node and both messages show up on node-1 and node-2 even if symKeyID is either node-1's or node-2's on shh.post() function.

Following code is run on node-1's geth-client:

node-1's symKeyID is given:

web3.shh.post({
  symKeyID: 'd5212e736703afbb21246e8acd192e4345ea910398544d765ed6b49f0ec524b5', //symKeyID of the node-1
  ttl: 10,
  topic: '0x07678231',
  powTarget: 2.01,
  powTime: 2,
  payload: web3.fromAscii("Hello there!")
  });

OR

---

Following code is run on node-2's geth-client:

node-2's symKeyID is given:

web3.shh.post({
  symKeyID: 'c4c4cecf6ad9499c2386b8ce6416f44684e042e491726b38315646c0b4afadc6', //symKeyID of the node-2
  ttl: 10,
  topic: '0x07678231',
  powTarget: 2.01,
  powTime: 2,
  payload: web3.fromAscii("Hello there!")
  });

Answer 2

Solution using Web3.py:

I have followed following ssh-mode code.

---

receiver.py that runs on node-1:

from os.path import expanduser
from web3 import HTTPProvider, Web3
import asyncio
import time


def handle_event(event):
    print(f"recipientPublicKey={event['recipientPublicKey'].hex()}")
    print(event["payload"].decode("utf-8"))


async def log_loop(filter_id, poll_interval):
    while True:
        for event in w3.geth.shh.getMessages(filter_id):  # event_filter.get_new_entries():
            handle_event(event)  # TODO: add try catch
        await asyncio.sleep(poll_interval)
        time.sleep(0.1)

if __name__ == "__main__":
    w3 = Web3(HTTPProvider("http://localhost:8545"))
    home = expanduser("~")
    topic = "0x07678231"

    print("Initializing...")
    key_id = w3.geth.shh.newKeyPair()  # generates a new public and private key pair for message decryption and encryption.
    public_key = w3.geth.shh.getPublicKey(key_id)
    filter_id = w3.geth.shh.new_message_filter({"topic": topic, "privateKeyID": key_id, "recipientPublicKey": public_key})
    print(f"my_public_key={public_key}")

    loop = asyncio.get_event_loop()
    try:
        loop.run_until_complete(asyncio.gather(log_loop(filter_id, 2)))
    finally:
        loop.close()

Output:

my_public_key=0x0429824f14966d802e8a12b09c276361cdf13eda4dd5f4f776d0a2a4db61ba4e24683be84df2b521ff8c6290e3851bf9b59a8e9a7e13345fee603de9be862f5ef3

---

After Node_1's messages are sent; I have copied printed receiverPublicKey into receiver_pub variable on the following code. I run following code on Node 2. Node 2 sends a message to the network. Later I press enter on the Node_1 and Node_1 prints the message

from web3 import Web3, HTTPProvider
web3 = Web3(HTTPProvider('http://localhost:8545'))

# obtained from node_1 and assigned here.
receiver_pub =
"0x0429824f14966d802e8a12b09c276361cdf13eda4dd5f4f776d0a2a4db61ba4e24683be84df2b521ff8c6290e3851bf9b59a8e9a7e13345fee603de9be862f5ef3"

topic = '0x07678231'
payloads = [web3.toHex(text="test message :)"), web3.toHex(text="2nd test message")]

web3.geth.shh.post(
    {"powTarget": 2.5, "powTime": 2, "ttl": 60, "payload": payloads[0], "topic": topic, "pubKey": receiver_pub}
)