Secret Drawing Board Guide: Create a Password-Protected Shared Canvas

Some ideas are hard to convey with text alone. Quick diagrams, handwritten notes, maps, explanatory sketches... But sharing these drawings can raise security concerns.

LOCK.PUB's Secret Drawing Board is a password-protected drawing canvas. Draw solo and share, or collaborate with others in real-time. All drawing data is end-to-end encrypted (E2E), so even the server cannot see the content.

How Does It Work?

1. Choose a mode -- Select Solo or Collaborative drawing
2. Set a password -- Set a password to access the drawing board
3. Generate a link -- A unique board link is created
4. Draw -- Freely draw on the canvas
5. Share -- Send the link and password so others can view or join

flowchart TD
    A[Choose mode] --> B[Set password]
    B --> C[Generate board link]
    C --> D[Send link + password]
    D --> E[Participant enters password]
    E --> F{Mode?}
    F -->|Solo| G[View only]
    F -->|Collaborative| H[Draw together]

Two Modes

Solo Drawing

Only the creator can draw. Others who enter the password can view the drawing only.

Use it when you want to:

• Securely share handwritten notes
• Draw and share a map or diagram
• Show a sketched idea to specific people only

Collaborative Drawing

Anyone with the password can draw on the canvas. All participants' drawings are synchronized in real-time.

Use it when you want to:

• Visualize ideas during team brainstorming
• Doodle together with friends for fun
• Use it as a whiteboard substitute during meetings

When to Use It

Maps & Directions

"Come in the building and turn left at..." Directions that are hard to explain in text become simple with a drawing.

Recommended settings:
- Mode: Solo drawing
- Password: A simple password
- Expiration: 24 hours
-> Easy way to share meeting point directions

Idea Sketches

Quickly sketch ideas that are hard to explain in words and share them with colleagues. Hand-draw UI wireframes, architecture diagrams, flowcharts, and more.

Education & Lessons

Teachers can draw solutions and share them with students, or use Collaborative mode to let students work through problems directly.

Fun & Games

Play drawing quizzes with friends, do relay drawing, or simply doodle together. The password keeps outsiders from joining.

Handwritten Messages

Send birthday wishes, thank-you notes, or encouraging messages in your own handwriting. Handwriting conveys sincerity better than typed text.

End-to-End Encryption (E2E)

All drawing data from the secret board is encrypted in the browser before being sent to the server.

sequenceDiagram
    participant U as User (Browser)
    participant S as Server
    participant R as Recipient (Browser)
    U->>U: Draw with pen
    U->>U: AES encryption (password as key)
    U->>S: Send encrypted strokes
    Note over S: Only encrypted data stored<br/>Drawing content unreadable
    R->>S: Access after entering password
    S->>R: Deliver encrypted data
    R->>R: AES decryption -> Display drawing

Only encrypted data is stored on the server, so even the LOCK.PUB team cannot see the drawing content.

Drawing Tools

Tool	Free	Pro
Pen colors	Black only	8 colors
Pen thickness	3 levels (thin/medium/thick)	3 levels
Eraser	Yes	Yes
Solo drawing	Yes	Yes
Collaborative drawing	Yes	Yes
Ink capacity	250KB	Unlimited

What Is Ink Capacity?

On the free plan, drawing data is limited to 250KB. This is enough for simple sketches and notes, but complex drawings require the Pro plan. An ink usage gauge is displayed on screen so you can check your remaining capacity.

Comparison with Other Tools

	Messenger Drawing	Google Jamboard	LOCK.PUB Secret Board
Password protection	No	No	Yes
End-to-end encryption	No	No	Yes
Signup required	Yes	Yes	No (for participants)
Auto-expiration	No	No	Yes (Pro)
Real-time collaboration	No	Yes	Yes
Server cannot view content	No	No	Yes

Usage Tips

Expiration Time (Pro)

With the Pro plan, you can set an expiration time for the drawing board.

Use Case	Recommended Expiration
Maps & directions	24 hours
Idea sketches	3 days
Education & lessons	7 days
Fun & doodles	1 hour

Send Password Through a Separate Channel

As with other secret content, send the link and password through different channels:

• Link via messenger / Password via text message
• Link via email / Password via phone call
• Never send link + password in the same message

Get Started

The secret drawing board is free to use. Create a board and start sharing right now.

Create a Secret Drawing Board ->