Python Encryption & Decryption Program

A Python program that implements a simple encryption and decryption algorithm for 4-digit integers.

Program Description

This program provides both encryption and decryption functionality:

• Encryption: Transforms 4-digit numbers using digit manipulation and swapping
• Decryption: Reverses the encryption process to recover original numbers

Encryption Algorithm

1. Take a 4-digit integer (abcd)
2. Add 7 to each digit and apply modulus 10
3. Swap positions: 1st↔3rd digit, 2nd↔4th digit
4. Output encrypted result

Decryption Algorithm

1. Take encrypted 4-digit integer
2. Add 3 to each digit and apply modulus 10
3. Swap positions: 1st↔3rd digit, 2nd↔4th digit
4. Output original number

Features

• Interactive command-line interface
• Input validation for 4-digit integers
• Mathematical encryption/decryption
• Clear step-by-step digit manipulation

Files

• encryption_program.py - Complete encryption/decryption implementation

Technologies Used

• Python 3
• Mathematical operations
• String manipulation
• Algorithm design

Author

Toh Qi Hao

How to Run

python encryption_program.py

Enter a 4 digits integer for encryption: 1234
==> Encrypted integer is 0189

Enter a 4 digits integer for decryption: 0189  
==> Decrypted integer is 1234