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
During World War II, information was a weapon.
A leaked message could change the course of a battle.
An instruction read by the opposing side could mean defeat.
One system used at that time was the Enigma machine—a machine that turned messages into sequences of characters that could not be understood without a specific key.
However, this system had one fundamental weakness.
The sender and receiver must have the same key.
A Problem That Was Never Solved
This system is known as symmetric encryption.
Meaning:
- messages are locked with one key
- messages are unlocked 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 via courier
- stored in a codebook
- or physically distributed
If that key falls into the wrong hands, all communication becomes insecure.
This problem is known as the key distribution problem, and for centuries no truly effective solution existed.
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 was born the concept of public key cryptography.
Key and Lock Analogy
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 only in one copy and is never shared.
If someone wants to send you something:
- they don’t need to ask for your 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 a secret upfront.
From Locks to Mathematics
In real implementations, there are no physical locks.
All of this is represented mathematically.
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.
But 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
Why This Matters for Blockchain
This concept becomes the main foundation in 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 managing ownership.
No reset mechanisms.
Ownership is entirely determined by one thing:
who holds the private key.
Conclusion
For centuries, humans have tried to protect information by sharing secrets in a limited way.
However, this approach always carries risks.
Public key cryptography changes this way of thinking.
It does not rely on trust,
but on mathematics.
And the same principle now forms the basis of blockchain.
In the next part, we will discuss something often used but rarely understood:
How someone can receive digital assets without having to reveal their identity.
That is where the role of public key and address begins to appear.
About the Author
Nitza Alfinas Rahman is a technology practitioner with over 18 years of experience in software engineering and 10 years in blockchain.
Keep following this series to understand how blockchain, Web3, and AI will change the way we build and manage businesses in the future.