When you open messaging apps like WhatsApp, you probably see alerts like:
Your messages are end-to-end encrypted.
But what does encryption actually mean?
What really happens technically when you send a message?
Imagine This Scenario
Suppose I want to send a secret message to my friend.
Before sending anything, I secretly tell my friend:
To understand my messages, move every letter one step backward in the alphabet.
So if my friend sees:
B
They know it actually means:
A
Because:
A → B
B → C
C → D
Every letter is shifted by one.
Now suppose my real message is:
HELLO
Before sending it, I transform every letter using the same rule:
H → I
E → F
L → M
L → M
O → P
So the encrypted message becomes:
IFMMP
Now I give YOU the paper containing:
IFMMP
and ask you:
Take this to my friend.
If someone steals the paper while you are carrying it, they will only see:
IFMMP
which looks meaningless unless they know the secret rule.
My friend, however, already knows the rule:
Move every letter one step backward.
So they can decode the message:
I → H
F → E
M → L
M → L
P → O
and recover:
HELLO
That secret rule is basically the key.
This Is Basically Encryption
Encryption means:
Transforming readable information into another form using a secret rule or key.
The original readable message is called:
Plain Text
And the transformed unreadable version is called:
Cipher Text
So in our example:
HELLO → Plain Text
IFMMP → Cipher Text
But Computers Do Not Understand Letters
Computers do not actually understand:
H
E
L
O
Computers only understand:
bits
0s
1s
As we explained in the previous article, every character inside a computer becomes a number.
For example:
H = 72
E = 69
L = 76
O = 79
And those numbers themselves become binary:
72 = 01001000
69 = 01000101
So inside a computer, your messages are really just numbers and bits.
Encryption Inside Computers
So inside a computer, your messages are really just numbers and bits.
Encryption at the computer level is basically taking those numbers and transforming them into other numbers using a reversible mathematical rule.
In simple words:
The computer changes the original numbers into different numbers in a way that can later be reversed using the correct key or formula.
For example, imagine we have a number like:
1
In binary, that becomes:
00000001
Now, suppose the computer applies a secret rule like:
add 5
So:
1 + 5 = 6
And now the stored value becomes:
00000110
Someone looking at the encrypted value only sees:
6
not the original:
1
To recover the original value, the receiver uses the reverse operation:
6 - 5 = 1
and the original data comes back again.
Modern encryption systems are much more advanced than simple addition and subtraction, but the core idea is still similar:
- - take original data
- - transform it using mathematics
- - Use a secret key
- - and make it unreadable without the correct way to reverse it
That transformed unreadable data is what we call:
Encrypted Data
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