Merge pull request #1680 from Harshit28j/cypher_buster_by_hj

Adding cypher buster script

Author: avinashkranjan

cipher_buster/cipher_buster.py

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+import math
+import sys
+# Caesar Cipher decryption function
+def caesar_decrypt(ciphertext, shift):
+    plaintext = ""
+    for char in ciphertext:
+        if char.isalpha():
+            ascii_offset = 65 if char.isupper() else 97
+            decrypted_char = chr((ord(char) - shift - ascii_offset) % 26 + ascii_offset)
+            plaintext += decrypted_char
+        else:
+            plaintext += char
+    return plaintext
+
+# Transposition Cipher decryption function
+def trans_decrypt(en_msg, k):
+    message = en_msg
+    key = k
+    numOfColumns = int(math.ceil(len(message) / float(key)))
+    numOfRows = k
+    numOfShadedBoxes = (numOfColumns * numOfRows) - len(message)
+    plaintext = [''] * numOfColumns
+    column = 0
+    row = 0
+    for symbol in message:
+        plaintext[column] += symbol
+        column += 1  # Point to the next column.
+        if (column == numOfColumns) or (column == numOfColumns - 1 and row >= numOfRows - numOfShadedBoxes):
+            column = 0
+            row += 1
+    return ''.join(plaintext)
+
+# Main program
+def main():
+    don_know = "[If you don't know the shift/key just press enter; the script will try all possible combinations then]"
+    print("Welcome to the Encryption Decryption Program!")
+
+    # Prompt user for encryption method
+    try:
+        method = int(input("Which encryption method would you like to decrypt?\nChoose number\n1) Caesar\n2) Transposition\n>"))
+    except ValueError:
+        print("Invalid selection")
+        sys.exit()
+        
+    # Prompt user for ciphertext
+    ciphertext = input("Enter the ciphertext to decrypt: ")
+
+    # Decrypt based on chosen method
+    if method == 1 and len(ciphertext)!=0:
+        shift = input(f"Enter the shift value used in the Caesar cipher:\n{don_know}\n>")
+
+        if shift == '':
+            for i in range(1, 26):
+                plaintext = caesar_decrypt(ciphertext, i)
+                print(plaintext)
+
+        elif shift.isnumeric():
+            shift = int(shift)
+            plaintext = caesar_decrypt(ciphertext, shift)
+            print(plaintext)
+
+        else:
+            print('Invalid Command')
+
+    elif method == 2 and len(ciphertext)!=0:
+        key = input(f"Enter the key used in the transposition cipher:\n{don_know}\n>")
+        if key == '':
+            for i in range(1, 26):
+                plaintext = trans_decrypt(ciphertext, i)
+                print(plaintext)
+
+        elif key.isnumeric():
+            key = int(key)
+            plaintext = trans_decrypt(ciphertext, key)
+            print(plaintext)
+
+        else:
+            print('Invalid Command')
+
+    else:
+        print("Invalid encryption method specified or No cipher text is given")
+
+# Run the program
+if __name__ == "__main__":
+    main()

cipher_buster/readme.md

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+# Cipher Buster: Brute Force Decryption for Caesar and Transposition Ciphers
+
+Cipher Buster is a Python script that performs a brute force attack on Caesar Cipher and Transposition Cipher encryption. It allows you to analyze the security of these encryption methods by attempting to crack them through an exhaustive search of all possible keys.
+
+## Features
+
+- Decrypt ciphertext encrypted using the Caesar Cipher.
+- Decrypt ciphertext encrypted using the Transposition Cipher.
+- Perform automatic brute force decryption by trying all possible shift values for Caesar Cipher or key values for Transposition Cipher.
+- User-friendly command-line interface for input and interaction.
+
+## Usage
+
+1. Make sure you have Python 3.x installed on your system.
+2. Clone this repository or download the `cipher_buster.py` file.
+3. Open a terminal or command prompt and navigate to the directory where the script is located.
+4. Run the script using the following command: python cipher_buster.py
+5. Follow the prompts to select the encryption method (Caesar or Transposition) and provide the ciphertext.
+6. If you know the shift value or key, enter it when prompted. Otherwise, leave it blank to try all possible combinations.
+7. The script will display the decrypted plaintext for each potential key or shift value.
+
+## Examples
+
+### Decrypting Caesar Cipher
+
+Which encryption method would you like to decrypt?
+Choose number:
+1) Caesar
+2) Transposition
+> 1
+
+Enter the ciphertext to decrypt: VQREQFGT
+
+Enter the shift value used in the Caesar cipher:
+[If you don't know the shift/key, just press enter; the script will try all possible combinations then]
+> 2
+
+TOPSECRET
+
+## Decrypting Transposition Cipher
+
+Which encryption method would you like to decrypt?
+Choose number:
+1) Caesar
+2) Transposition
+> 2
+
+Enter the ciphertext to decrypt: AEIMNORTUAYOBCEFHLPET
+
+Enter the key used in the transposition cipher:
+[If you don't know the shift/key, just press enter; the script will try all possible combinations then]
+> 
+
+IMAHIDDENMESSAGEFORYOU