# GeoVLogReader  
**Console utility to decrypt and extract GeoV‑encrypted HDF5 flight logs**

GeoVLogReader is the ground‑station companion to **GeoVLogSvc** (the Windows‑service logger running in the aircraft).  
It performs three jobs:

1. **Authenticates** the log header and retrieves the wrapped AES‑256 key.  
2. **Unwraps / decrypts** that key using **your private RSA key** *(which never leaves your office PC)*.  
3. **Streams the plaintext dataset** out to one of three targets  
   * another HDF5 file (`--out-file`)  
   * a folder of CSV slices (`--csv`)  
   * **STDOUT** (for piping straight into Python/R).

> **Crypto stack**  
> * **AES‑256‑GCM** — per‑chunk encryption inside HDF5  
> * **RSA‑2048 OAEP‑SHA‑256** — wraps each file’s AES key  
> * **H5Z‑AES** plugin — on‑the‑fly decrypt for HDF5

---

## 1 · Quick start (pre‑built binaries)

```powershell
# 1. Unzip release bundle
Expand-Archive GeoVLogReader-win-x64.zip -DestinationPath C:\GeoVReader

# 2. Tell the tool where your private key lives (once per session/user)
$env:GEOVLOG_PRIVATE_KEY = "D:\Keys\GeoVLogPrivate.pem"

# 3. Decrypt a flight hour
C:\GeoVReader\GeoVLogReader.exe `
    --in        F:\Flights‚50521_0930_GeoVLog.h5 `
    --out-file  D:\Decrypted‚50521_0930_plain.h5
```

---

## 2 · Command‑line reference

| Option | Alias | Required | Description |
|--------|-------|----------|-------------|
| `--in <file>` | `-i` | ✔ | Encrypted `.h5` produced by GeoVLogSvc |
| `--out-file <file>` |  | ✖ | Write a fully decrypted HDF5 copy |
| `--csv <folder>` |  | ✖ | Split into per‑sensor CSV files instead of HDF5 |
| `--key <pem>` | `-k` | ✖ | Path to private key (overrides `GEOVLOG_PRIVATE_KEY`) |
| `--overwrite` |  | ✖ | Replace existing output files |
| `--summary` | `-s` | ✖ | Print header info only (no extraction) |
| `--help` | `-h` | – | Show full usage |

*If neither `--out-file` nor `--csv` is specified GeoVLogReader streams a row‑wise CSV to **STDOUT**.*

---

## 3 · Prerequisites

| Component | Version | Notes |
|-----------|---------|-------|
| **.NET Runtime** | ≥ 8.0 | Bundled with release; no install needed on most PCs |
| **OpenSSL** | ≥ 1.1 | Only for key‑pair generation / rotation (office side) |
| **H5Z‑AES** | ≥ 0.3 | DLL included; loader uses `HDF5_PLUGIN_PATH` |

---

## 4 · Typical workflow

1. **Flight ends** → copy encrypted logs to ground PC.  
2. Run  
   ```powershell
   GeoVLogReader -i E:\Flights‚50521_09_GeoVLog.h5 `
                 --out-file D:\Survey09_plain.h5
   ```
3. Analyse in Python  
   ```python
   import h5py, pandas as pd
   with h5py.File("Survey09_plain.h5") as f:
       df = pd.DataFrame(f["/measurements"][:])
   ```

---

## 5 · Building from source

```powershell
git clone https://yourrepo/GeoVLog.git
cd GeoVLog/src/GeoVLogReader

dotnet build -c Release

# Publish single‑file, self‑contained binary
dotnet publish -c Release -r win-x64 `
               /p:PublishSingleFile=true /p:PublishTrimmed=true
```

---

## 6 · Key management

| Item | Stored where | Purpose |
|------|--------------|---------|
| **Public key** (embedded) | Aircraft EXE | Wrap file AES keys (not secret) |
| **Private key** (`GeoVLogPrivate.pem`) | Analyst PC + offline vault | Unwrap AES keys; keep secure |
| `GEOVLOG_PRIVATE_KEY` env var | Analyst profile or CI secret store | Path override for automated runs |

**Rotation**

1. Generate new RSA pair.  
2. Embed new *public* key in GeoVLogSvc, re‑sign, redeploy.  
3. Retain old private keys to read historic files.

---

## 7 · Troubleshooting

| Symptom | Possible causes |
|---------|-----------------|
| `ERROR: key unwrap failed` | Wrong private key or file logged with newer key pair |
| `Cannot load H5Z-AES filter` | `HDF5_PLUGIN_PATH` not set or DLL missing |
| `Access denied` opening key | File ACL blocks current user or bad key path |

Use `--summary` to validate header and key fingerprint.

---

## 8 · Tests

```powershell
dotnet test ..\..	ests\GeoVLog.Tests --filter Category=Reader
```

Unit tests cover header auth, AES‑GCM tag verify, and CSV round‑trip.

---

## 9 · License & credits

GeoVLogReader © 2025 Your Company Name – MIT license.  
Uses:

* **System.CommandLine** (MIT)  
* **HDF5 & H5Z‑AES** (BSD)  
* **BouncyCastle** (MIT) for PEM parsing

---

*Need help?* Open an issue in the **geoVlog-reader** tracker or email  
**support@your-company.com**.