Encryption and Decryption

In today’s digital world, protecting information is very important. Whether it’s personal data, banking details, or online communication, encryption and decryption ensure that sensitive information stays secure.

What is Encryption?

Encryption is the process of converting a normal, readable message (plaintext) into an unreadable format called ciphertext.

This ciphertext looks meaningless and cannot be understood without a proper decryption key.

Example:

Plaintext:
HELLO

Ciphertext:
KHOOR

Here, each letter is shifted by 3 positions (Caesar Cipher).

Caesar Cipher
The Caesar cipher is a very simple and old method of hiding messages. It works by changing each letter in a message to another letter by moving a fixed number of steps in the alphabet.

For example, if we use a shift of 3:

A becomes D
B becomes E

So, every letter is just moved 3 positions forward (or backward) to create a secret message.

Types of Encryption
1. Symmetric Encryption

• Uses the same key for encryption and decryption
• Faster and efficient

2. Asymmetric Encryption
Uses two keys:

• Public Key (for encryption)
• Private Key (for decryption) More secure but slower

What is Decryption?

Decryption is the reverse process of encryption. It converts the unreadable ciphertext back into its original readable form (plaintext).

It is the reverse of encryption.

Example:

Cipher text:
KHOOR

Decrypted:
HELLO

How Encryption and Decryption Work

1. A sender writes a message (plaintext)
2. Encryption algorithm + key converts it into ciphertext
3. The encrypted data is transmitted
4. The receiver uses a key to decrypt it
5. The original message is restored

Why Encryption and Decryption are Important

• Maintain privacy
• Protect sensitive data
• Secure communication over the internet
• Prevent cyber attacks and data theft

They ensure confidentiality, integrity, and security of information.