adding file to repo

Author: Aakash02A

caesar_cipher/README.md

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+# 🛡️ Caesar Cipher Tool
+
+A command-line utility to **encrypt** and **decrypt** messages using the Caesar Cipher algorithm. Great for learning basic cryptography, creating puzzles, or encoding secret messages within a local or collaborative environment.
+
+---
+
+## 🔐 What is Caesar Cipher?
+
+Caesar Cipher is a substitution cipher where each letter in the plaintext is shifted by a fixed number (shift key) of positions down the alphabet.
+
+### Example (Shift = 3):
+- A → D
+- B → E
+- X → A
+- Z → C
+
+> **Encryption**: Shift letters forward  
+> **Decryption**: Shift letters backward
+
+---
+
+## 📦 Features
+
+- Encrypt or decrypt any string using a simple shift
+- Supports both uppercase and lowercase
+- Leaves spaces, numbers, and punctuation unchanged
+- Command-line interface for real-time usage
+
+---
+
+## ⚙️ Usage
+
+### 🔧 Requirements
+- Python 3.x installed
+
+### 🏃 Run via Command Line
+
+```bash
+python caesar_cipher_tool.py <mode> <shift> "<text>"
+````
+
+* `<mode>`: `e` for encrypt, `d` for decrypt
+* `<shift>`: Number of positions to shift
+* `<text>`: The message to process (wrap in quotes)
+
+---
+
+## 🧪 Examples
+
+### Encrypt:
+
+```bash
+python caesar_cipher_tool.py e 4 "meet at library at 5pm"
+```
+
+Output:
+
+```
+Result: qiix ex plevvex ex 5ts
+```
+
+### Decrypt:
+
+```bash
+python caesar_cipher_tool.py d 4 "qiix ex plevvex ex 5ts"
+```
+
+Output:
+
+```
+Result: meet at library at 5pm
+```
+
+---
+
+## 💡 Real-world Scenario
+
+You and a friend agree on a shift value (e.g., 4). You encrypt a secret note and send it. Your friend uses the same script and shift value to decrypt it.
+
+---
+
+## 🛠️ How It Works
+
+The script:
+
+1. Loops through each character in the message.
+2. Applies a shift based on encryption or decryption mode.
+3. Converts characters using ASCII math and wraps alphabetically using `% 26`.
+4. Non-alphabet characters are preserved.
+
+```python
+chr((ord(char) - base + shift) % 26 + base)
+```
+
+* `ord(char)` – ASCII of char
+* `base` – `ord('a')` or `ord('A')`
+* `shift` – Provided shift value
+
+---
+
+## 🧑‍🎓 Author
+
+Built by Aakash — focused on cybersecurity, scripting, and real-world learning through hands-on tools.
+
+---
+
+

caesar_cipher/encryp decryp.py

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+# Caesar Cipher Encryption/Decryption
+
+def encrypt(text, shift):
+    result = ''
+    for char in text:
+        if char.isalpha():
+            base = ord('A') if char.isupper() else ord('a')
+            result += chr((ord(char) - base + shift) % 26 + base)
+        else:
+            result += char  # Keep spaces/symbols as is
+    return result
+
+def decrypt(text, shift):
+    return encrypt(text, -shift)
+
+def main():
+    choice = input("Type 'encrypt' or 'decrypt': ").strip().lower()
+    
+    if choice not in ['encrypt', 'decrypt']:
+        print("Invalid choice. Please type 'encrypt' or 'decrypt'.")
+        return
+
+    message = input("Enter your message: ")
+    
+    try:
+        shift = int(input("Enter shift value (0-25): ")) % 26
+    except ValueError:
+        print("Shift must be a number.")
+        return
+
+    if choice == 'encrypt':
+        print("Encrypted message:", encrypt(message, shift))
+    else:
+        print("Decrypted message:", decrypt(message, shift))
+
+if __name__ == '__main__':
+    main()