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A full-stack desktop simulation of secure, reliable message delivery — encryption, error coding, noisy channel injection, ACK/NACK retransmission, and real-time analytics — all in one polished engineering dashboard.
This application lets you visually explore how data travels securely over an unreliable network. Every layer of the classic transmission stack is simulated and inspectable:
| Category | Details |
|---|---|
| Encryption | AES-CBC (128/192/256-bit key) · Substitution cipher |
| Error Coding | Hamming(7,4) single-bit correction · CRC-based detection |
| Channel Model | Single-bit · Multi-bit · Burst error injection, configurable probability + seed |
| Protocol | ACK/NACK receiver logic · Automatic retransmission controller |
| UI | 6-tab Qt dashboard — Simulation, Frame Analysis, Statistics, Comparison, Logs, Settings |
| Analytics | Live charts (Matplotlib), experiment runner, metrics export |
| Export | Logs, session snapshots, and metrics to file |
| Testing | Pytest suite covering AES, CRC, Hamming, channel, protocol, and integration |
Configure message, encryption, coding scheme, error model and probability, then fire a transmission and watch the ACK/NACK pipeline live.
Side-by-side view of every transformation: original plaintext → encrypted payload → encoded frame → noisy frame → corrected frame → final decrypted message.
Bit-level inspection of the frame with parity positions highlighted, channel-modified bits marked in red, and Hamming-corrected bits in green.
Timestamped chronological trace of every protocol event — prepare, send, channel, NACK, retry, drop — with search/filter and one-click export.
Session-wide KPIs (BER, throughput, retransmission rate, success rate) with live Matplotlib charts: retransmissions per packet, detected vs corrected errors, success trend.
Automated batch runs across all four combinations (AES/Substitution × Hamming/CRC) under identical noise conditions, producing a side-by-side results matrix.
Persist default theme, encryption mode, coding scheme, retry limit, error model and probability so every session starts from a stable baseline.
Secure Transmission Protocol Simulator/
│
├── app/
│ ├── main.py # Application entry point (PySide6 QApplication)
│ ├── config.py # App name, org, and persistent settings model
│ └── theme.py # Global Qt stylesheet builder
│
├── core/
│ ├── crypto/
│ │ ├── aes_cipher.py # AES-CBC encrypt / decrypt wrapper
│ │ ├── substitution_cipher.py
│ │ └── crypto_utils.py # Base64 helpers
│ ├── coding/
│ │ ├── hamming74.py # Hamming(7,4) encode / decode / correct
│ │ ├── crc_codec.py # CRC encode / verify
│ │ └── bit_utils.py
│ ├── channel/
│ │ ├── noisy_channel.py # Configurable error injector (single/multi/burst)
│ │ └── error_models.py # ErrorMode enum
│ ├── protocol/
│ │ ├── sender.py # Frame builder and transmit logic
│ │ ├── receiver.py # Frame validator, ACK/NACK decision
│ │ ├── ack_nack.py # ACK/NACK data model
│ │ ├── retransmission.py # Retry controller
│ │ └── transmission_controller.py
│ ├── analytics/
│ │ ├── metrics.py # BER, throughput, retransmission counters
│ │ ├── charts.py # Matplotlib figure factories
│ │ └── experiment_runner.py # Batch experiment engine
│ └── models/ # Shared data models
│
├── ui/
│ ├── main_window.py # Tab host and menu bar
│ ├── simulation_tab.py # Main send/receive control panel
│ ├── frame_analysis_tab.py # Bit-level frame inspector
│ ├── statistics_tab.py # Live analytics charts
│ ├── comparison_tab.py # A/B experiment view
│ ├── logs_tab.py # Scrollable transmission log
│ ├── settings_tab.py # Persistent configuration form
│ ├── widgets/ # Reusable custom Qt widgets
│ └── dialogs/ # Modal dialogs
│
├── tests/
│ ├── conftest.py
│ ├── test_aes.py
│ ├── test_channel.py
│ ├── test_crc.py
│ ├── test_hamming.py
│ ├── test_protocol.py
│ └── test_integration.py
│
├── requirements.txt
└── README.md
| Layer | Technology |
|---|---|
| Desktop UI | PySide6 (Qt 6 Python bindings) |
| Cryptography | pycryptodome — AES-CBC |
| Charts | Matplotlib embedded in Qt |
| Testing | pytest |
| Language | Python 3.11+ |
git clone https://github.com/Fadi-AICH/Secure-Transmission-Protocol-Simulator.git
cd Secure-Transmission-Protocol-Simulator# Windows
py -3.11 -m venv .venv
.venv\Scripts\activate
# macOS / Linux
python3.11 -m venv .venv
source .venv/bin/activatepip install -r requirements.txtpython -m app.mainpytestOr with verbose output:
pytest -v --tb=shortThe test suite covers:
- AES encrypt/decrypt round-trip
- Hamming(7,4) encode/decode/single-bit correction
- CRC encode/verify and error detection
- Noisy channel error injection (all modes)
- Protocol sender/receiver ACK/NACK flow
- End-to-end integration transmission
- User types a message and picks encryption + coding settings in the Simulation tab.
- Sender encrypts the plaintext (AES-CBC or substitution cipher) then encodes each frame with Hamming(7,4) or appends a CRC checksum.
- Noisy channel flips bits according to the selected error model (single, multi, or burst) at the configured probability. A seed makes runs reproducible.
- Receiver checks each frame: Hamming corrects a single-bit flip silently; CRC detects any corruption and triggers a NACK. On ACK the frame is accepted and decrypted.
- Retransmission controller resends NACK'd frames up to the configured retry limit.
- Analytics accumulate BER, throughput, and retransmission rate across the session and render live charts.
| Mode | Behaviour |
|---|---|
NONE |
Perfect channel — no errors injected |
SINGLE |
At most one random bit flip per frame |
MULTI |
Each bit independently flipped with probability p |
BURST |
A contiguous run of flips starting at a random offset |
All persistent settings (default encryption mode, coding scheme, channel probability, retry limit, theme) are saved between sessions via Qt's QSettings and managed through the Settings tab in the UI.
This project is released for educational and research purposes.