Turning Fantasy into Reality: Why I Built Dead Man's Switch and How Its Security Works

It Started with Admiration for "That Scene from Comics"

"If I die, the information I've stored will be released to the world..."

This line, spoken by characters whose lives are threatened in spy movies and suspense manga to deter their enemies. Haven't many of us felt it was "cool" at least once?

My motivation for developing this service, Dead Man's Switch, came from pure curiosity to make this "mechanism that releases truth in emergency situations" work in the real world.

What is Dead Man's Switch?

"Dead Man's Switch" originally refers to a safety device on trains that automatically applies the brakes when the conductor loses consciousness.

This system applies that concept to realize:

• Regular survival confirmation (login)
• Automatic message sending when confirmation stops
• Safely storing important information and delivering it in emergencies

How "Play" Became "Digital End-of-Life Planning" Through One Realization

Initially, I was building this as an extension of "play" - sending messages if there's no login within a specified period. However, while designing the core "survival confirmation (trigger)" of the system, I came up with a rational mechanism.

"When a credit card payment fails, isn't that a sign that something has happened to the registered user?"

The Idea of Payment-Linked Triggers

When payments stop, there's a very high probability that the person can no longer continue that intention. By using "payment failure" as a trigger, what was a mere gimmick evolved into a practical "digital end-of-life planning service" for delivering important information to surviving family members.

Flexible Response with Two Plans

Currently, this service offers:

Free Plan

• Realizes the original "playful" experience
• Survival confirmation through regular login
• Basic notification email function

Premium Plan

• More reliable "payment-linked digital end-of-life planning"
• Automatic payment failure detection
• Multiple notification recipient settings
• File attachment function

This allows usage according to different needs.

Development Impossible Alone: AI Became the Perfect Partner

Even with ideas, it would have taken enormous time to shape the entire system alone in the past. The latest AI tools provided that assistance.

Realizing Development with AI Support

While building on past system development experience, through dialogue with AI and repeated trial and error, I was able to independently complete:

• Server construction
• Database design
• Security implementation
• User interface design
• Multi-language support (Japanese, English, Chinese)

AI as a "Skilled Partner"

AI is not just an automation tool, but as a "skilled partner" for shaping the developer's vision, it reflected my design philosophy into every corner of the system.

Development Flow:

1. Consult with AI about ideas
2. Receive implementation method proposals
3. Generate and improve code
4. Test and debug
5. Security check

By repeating this cycle, I was able to realize an enterprise-level service as an individual.

Proof of Trust: A "Box That Cannot Be Opened" Even by Administrators

Due to the nature of digital end-of-life planning, the data handled includes extremely sensitive information such as messages to loved ones and passwords. Therefore, I pay the utmost attention to information handling.

Robust Encryption System

Even I, as the administrator, cannot restore the stored content.

Data is protected in a strictly encrypted state and is designed to be delivered only to your designated recipients at the predetermined "moment of emergency."

Security Features:

1. AES-256-CBC Encryption

   • Military-grade encryption method adopted
   • Different encryption keys for each user

2. Column-Level Encryption

   • Message content
   • Email subject
   • Attached files All encrypted individually

3. Cannot Be Decrypted Even with Administrator Privileges

   • Encryption keys safely managed server-side
   • Decryption automatically executed only during sending
   • Direct human access impossible

4. Two-Factor Authentication Support

   • Email authentication code
   • TOTP (Google Authenticator, etc.)
   • Secure login function

Additional Recommendations for Safety

While the system provides maximum protection, for even greater security:

We strongly recommend additional measures such as password-protecting attached files themselves.

Recommended Double Protection:

• Password protection for ZIP files
• Password settings for PDF files
• Transmit important information in separate messages

Technology Supporting System Reliability

1. Regular Monitoring System

Automatic access status check at 5-minute intervals:

• Check last login time
• Determine set monitoring interval
• Send automatic notification emails

2. Stripe Payment Integration (Premium Plan)

Integration with payment system:

• Automatic payment failure detection
• Multiple retry confirmation
• Highly reliable anomaly detection

3. Ensuring Redundancy

• Database
• Regular automatic backups
• Automatic retry mechanism on errors

4. 24/7 Operation

Stable operation with Docker containers:

• Automatic restart function
• Health checks
• Logging

Why I Made This Service Public

1. To Help Others with the Same Concerns

"I can't tell my family passwords in emergencies" "I don't know how to pass on important information"

Many people have these concerns.

2. Solving Social Issues with Technology

Precisely because we're in an increasingly digital age:

• Digital legacy issues
• Difficulty in password management
• Emergency information sharing

I wanted to provide technological answers to these challenges.

3. Proving What Individuals Can Do

With the evolution of AI technology:

• Individual developers can create full-fledged services
• Anything is possible with just an idea
• Democratization of technology

I also wanted to prove this.

Continuing Evolution Based on User Feedback

The service has just been launched, but it will continue to evolve based on user feedback.

Future Improvement Plans:

• Further security enhancements
• Feature additions (based on user requests)
• UI improvements
• Mobile app consideration

Summary: The Joy of Making Fantasy Real

"Mechanisms for emergencies" that appear in manga and spy movies.

A project that started from simple curiosity to make them real has grown into a practical service preparing many people for their "emergencies."

What I Learned Through Development:

• Technology is a tool for shaping thoughts
• AI is the best development partner
• Security cannot be compromised
• User feedback is most important

Why Not Start with the Free Plan?

Dead Man's Switch allows unlimited use of basic functions even with the free plan:

• Survival confirmation system
• Notification email sending (up to 3)
• Secure login
• Two-factor authentication

Even if you feel resistance to the term "digital end-of-life planning," please try it casually as an "interesting gimmick" first.

And when you really need it, it will surely help your loved ones.