# Split Encoding

Split Encoding distributes your secret across multiple images. **All images are required** to reconstruct the message.

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## How It Works

Your secret is divided into chunks, each encrypted and hidden in a separate image:

```
┌─────────────────────────────────────────────────────────────┐
│                    Your Secret Message                      │
├─────────────────────────────────────────────────────────────┤
│                           │                                 │
│              ┌────────────┼────────────┐                    │
│              ▼            ▼            ▼                    │
│         ┌────────┐   ┌────────┐   ┌────────┐                │
│         │ Part 1 │   │ Part 2 │   │ Part 3 │                │
│         │ Image  │   │ Image  │   │ Image  │                │
│         └────────┘   └────────┘   └────────┘                │
│                                                             │
│         All 3 required to reconstruct the message           │
└─────────────────────────────────────────────────────────────┘
```

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## Use Cases

### Distributed Trust
Split a master password across images stored in different locations:
- Image 1: Your phone
- Image 2: Cloud storage
- Image 3: USB drive at home

### Team Access
Share access that requires multiple people:
- Each team member holds one image
- All must collaborate to decode

### Dead Man's Switch
Information that should only be accessible if multiple conditions are met.

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## How to Use Split Encoding

### Encoding

1. Select the **Split** tab in Encode mode
2. Select **multiple cover images** (2 or more)
3. Enter your secret message or file
4. Enter a password
5. Click **Encode**
6. Save each encoded image

### Decoding

1. Switch to **Decode** mode
2. Select the **Split Decode** tab
3. Load **all** the split images (in any order)
4. Enter the password
5. Click **Decode**

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## Important Notes

### ⚠️ All Parts Required

If you lose **any** image, the data is **gone forever**. There's no recovery option.

| Images Provided | Result |
|-----------------|--------|
| All images + correct password | ✅ Message recovered |
| Missing 1 image | ❌ Cannot decode |
| Wrong password | ❌ Cannot decode |

### 💡 Best Practices

1. **Keep backups** of all split images in separate locations
2. **Number your images** or use clear naming (part1.png, part2.png, etc.)
3. **Test decoding** immediately after encoding to verify
4. **Document the split** — record how many parts exist
5. **Use the same password** for all parts (required)

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## Technical Details

### Chunk Distribution

Data is split using a deterministic algorithm:
- Each chunk gets a sequence number (1, 2, 3...)
- Chunks are independently encrypted
- Each image stores one chunk + metadata

### Metadata Stored

Each split image contains:
```
┌─────────────────────────────────┐
│  Split Metadata                 │
├─────────────────────────────────┤
│  Part Number:  2                │
│  Total Parts:  3                │
│  Chunk Hash:   SHA-256          │
│  Session ID:   Random UUID      │
└─────────────────────────────────┘
```

The Session ID ensures parts from different encoding sessions can't be mixed.

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## Comparison: Standard vs Split

| Feature | Standard | Split |
|---------|----------|-------|
| Images needed | 1 | 2+ |
| Single point of failure | Yes | No |
| Storage requirement | Lower | Higher |
| Complexity | Simple | Moderate |
| Use case | Personal secrets | Distributed trust |