This article is the first part of a series discussing blockchain designed for a non-technical audience—business owners, decision-makers, and anyone who wants to understand this technology practically.

We will not start with technical terms.
We will start with a real problem that existed long before blockchain.

When Information Determines Victory

In World War II, information was a weapon.

A leaked message could change the course of a battle.
An instruction read by the enemy could mean defeat.

One system used at the time was the Enigma machine—a machine that transformed messages into a series of characters that could not be understood without a specific key.

However, this system had one fundamental weakness.

The sender and receiver had to have the same key.

A Problem That Never Ends

This system is known as symmetric encryption.

It means:

  • the message is locked with a key
  • the message is opened with the same key

The problem is simple but very difficult to solve:

How to share the key… without leaking it?

In practice:

  • the key must be sent by courier
  • stored in codebooks
  • or physically distributed

If the key falls into the wrong hands, all communication becomes insecure.

This problem is known as the key distribution problem, and for centuries there was no truly effective solution.

A Fundamental Change

In 1976, two scientists, Whitfield Diffie and Martin Hellman, introduced a concept that completely changed this approach.

They proposed something previously considered impossible:

Two parties can communicate securely without ever sharing a secret key.

From this arose the concept of public key cryptography.

Analogy of Keys and Locks

To understand this, imagine everyone can create their own system:

  • A lock
  • A key

Everyone is free to make their own locks.
They can even make many duplicate locks and share them with anyone.

However, the key to open those locks exists in only one copy and is never shared.

If someone wants to send you something:

  • they don't need to ask for a key
  • they just need to use your lock

Once something is locked with that lock, no one can open it—except you.

The fundamental difference from the previous system is:

There is no longer a need to share secrets upfront.

From Locks to Mathematics

In real implementations, there are no physical locks.

All of this is represented in mathematical form.

y = 3x + 2

In this simple analogy:

  • x is the private key (secret)
  • y is the public key (can be shared)

You can share the value of y with anyone.
However, the value of x remains a secret known only to you.

In real systems, the function used is much more complex and designed so that:

  • it is easy to compute forward
  • very difficult to reverse back

Why This Is Important for Blockchain

This concept becomes the main foundation of blockchain.

Each user has a private key that serves as proof of ownership of their digital assets.

  • The public key or address can be shared
  • The private key is never shared

There is no central authority regulating ownership.
There is no reset mechanism.

Ownership is entirely determined by one thing:

who holds the private key.

Closing

For centuries, humans tried to protect information by sharing secrets in a limited manner.

But this approach always carried risks.

Public key cryptography changed this way of thinking.

It does not rely on trust,
but rather on mathematics.

And the same principle now forms the basis of blockchain.

In the next part, we will discuss something that is often used but rarely understood:

How someone can receive digital assets without having to reveal their identity.

This is where the role of public key and address begins to appear.

About the Author

Nitza Alfinas Rahman is a technology practitioner with more than 18 years of experience in software engineering and 10 years in blockchain.

Keep following this series to understand how blockchain, Web3, and AI will transform how we build and manage businesses in the future.

If you want to understand how this technology is used in real life in Indonesia—for business, government, and startups— please read our complete guide on blockchain in Indonesia.