Add README for mix simulation and scripts (#56)

scripts/README.md

@@ -0,0 +1,22 @@
+# Nomos Blend Simulation Result Analysis
+
+First of all, run the Nomos Blend simulation by following the [instruction](../simlib/mixnet-sims/).
+
+## Latency Analysis
+
+```bash
+python3 latency.py <log_path>
+```
+This script calculates the minimum, average, median, and maximum latency taken by data messages to reach the final blend node.
+
+## Anonymity Analysis
+
+```bash
+python3 -m venv .venv
+source .venv/bin/activate
+pip install -r requirements.txt
+
+python3 emission.py --log-path <log_path> --plot-png-path <plot_png_path>
+```
+This script draws a scatter plot of emission events from all nodes
+to see how many messages (data or cover) were emitted at the same time window.

simlib/mixnet-sims/README.md

@@ -0,0 +1,88 @@
+# Nomos Blend Simulation
+
+## Features
+
+- The simulation runs multiple Nomos Blend nodes using [netrunner](../netrunner).
+- Each node implements the Nomos Blend Tier 1~3 protocols.
+    - [Persistent Transmission](https://www.notion.so/Nomos-Blend-Network-Tier-1-Persistent-Transmission-Module-10b8f96fb65c807cb1e8f92a7f41a771?pvs=4)
+    - [Message Blending](https://www.notion.so/Nomos-Blend-Network-Tier-2-Message-Blending-Module-1208f96fb65c80e5bcb9df6e27472339?pvs=4)
+    - [Cover Traffic](https://www.notion.so/Nomos-Blend-Network-Tier-3-Cover-Traffic-Module-10b8f96fb65c80cab153de10115e0023?pvs=4)
+    - Also, each node generates data messages probabilistically (similar as the consensus protocol).
+- The simulation prints logs that can be used to analyze the following properties.
+    - Latency
+    - Bandwidth
+    - Anonymity
+
+## Configurations
+
+The simulation can be configured by [config/mixnode.json](./config/mixnode.json).
+
+### `step_time` and `network_settings`
+
+We recommend setting the step time equal to the minimum latency in the network settings,
+in order to speed up the simulation.
+For example, if all regions are used, and if the minimum latency is 40ms (asia:asia),
+we recommend setting the step time to 40ms.
+
+### `wards.sum`
+
+The simulation runs until the `wards.sum` number of messages (data or cover) arrive in
+their last blend node and finally fully unwrapped.
+
+### Network Topology
+
+The simulation constructs a network with the `node_count` number of nodes.
+Each node establish connections with the `connected_peers_count` number of nodes randomly selected.
+
+### Protocol Parameters
+
+#### Tier 1: Persistent Transmission
+
+```json
+"persistent_transmission": {
+  "max_emission_frequency": 1.0,
+  "drop_message_probability": 0.0
+},
+```
+We recommend setting `max_emission_frequency` to [1 message per second](https://www.notion.so/Nomos-Blend-Network-Tier-1-Persistent-Transmission-Module-10b8f96fb65c807cb1e8f92a7f41a771?pvs=4#11f8f96fb65c80dfbd23e4400feaaf9c),
+which is the same as the expected maximum message frequency configured in the consensus protocol
+that will use the Nomos Blend protocol.
+
+To disable [drop messages](https://www.notion.so/Nomos-Blend-Network-Tier-1-Persistent-Transmission-Module-10b8f96fb65c807cb1e8f92a7f41a771?pvs=4#11c8f96fb65c804db7ccfd024f8c44d0), set `drop_message_probability` to 0.
+
+#### Tier 2: Message Blending
+
+```json
+"number_of_mix_layers": 2,
+"max_delay_seconds": 10
+```
+
+The `number_of_mix_layers` is a parameter for the [Cryptographic Processor](https://www.notion.so/Nomos-Blend-Network-Tier-2-Message-Blending-Module-1208f96fb65c80e5bcb9df6e27472339?pvs=4#1208f96fb65c80f8a8d3d2b449953bde). And, the `max_delay_seconds` is for [Temporal Processor](https://www.notion.so/Nomos-Blend-Network-Tier-2-Message-Blending-Module-1208f96fb65c80e5bcb9df6e27472339?pvs=4#1208f96fb65c80dca885dda33fbd599b), which is the same as $\Delta_{max}$ in the specification.
+
+#### Tier 3: Cover Traffic
+
+```json
+"epoch_duration": "432000s",
+"slot_duration": "20s",
+"slots_per_epoch": 21600,
+"number_of_hops": 2,
+```
+These parameters are defined in the [specification](https://www.notion.so/Nomos-Blend-Network-Tier-3-Cover-Traffic-Module-10b8f96fb65c80cab153de10115e0023?pvs=4#12f8f96fb65c80d094b6f31306c65b70).
+In short, each node selects the `slots_per_epoch / node_count * (1 / number_of_hops)` number of slots
+at the beginning of each epoch. At every selected slot, the node generates a cover message.
+
+
+## Running the simulation
+
+```bash
+cargo build --release
+../target/release/mixnet-sims --input-settings ./config/mixnode.json
+```
+The simulation prints a bunch of logs that can be used for analysis.
+We recommend piping logs to a file.
+
+## Analysis
+
+To analysis logs for latency and anonymity, see the README in the [scripts](../../scripts/).
+
+The bandwidth consumed by each node is printed as a log at the end of the simulation.

simlib/mixnet-sims/config/mixnode.json

@@ -20,7 +20,7 @@
   "node_settings": {
     "timeout": "1000ms"
   },
-  "step_time": "10ms",
+  "step_time": "40ms",
   "runner_settings": "Sync",
   "stream_settings": {
     "path": "test.json"
@@ -30,20 +30,20 @@
   "record_settings": {},
   "wards": [
     {
-      "sum":2 
+      "sum": 10
     }
   ],
   "connected_peers_count": 4,
   "data_message_lottery_interval": "20s",
   "stake_proportion": 1.0,
   "epoch_duration": "432000s",
-  "slot_duration": "1s",
-  "slots_per_epoch": 432000,
-  "number_of_hops": 1,
+  "slot_duration": "20s",
+  "slots_per_epoch": 21600,
+  "number_of_hops": 2,
   "persistent_transmission": {
     "max_emission_frequency": 1.0,
     "drop_message_probability": 0.0
   },
-  "number_of_mix_layers": 1,
+  "number_of_mix_layers": 2,
   "max_delay_seconds": 10
 }