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Commit f59af82

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Add text encryption script
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‎text_encryption/encryption_method.py

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import string
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import sys
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# Caesar cipher encryption
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def caesar_cipher_encrypt(text, shift):
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encrypted_text = ""
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for char in text:
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if char.isalpha():
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alphabet = string.ascii_uppercase if char.isupper() else string.ascii_lowercase
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encrypted_char = alphabet[(alphabet.index(char) + shift) % len(alphabet)]
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encrypted_text += encrypted_char
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else:
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encrypted_text += char
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return encrypted_text
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# Affine cipher encryption
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def affine_cipher_encrypt(text, a, b):
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encrypted_text = ""
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for char in text:
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if char.isalpha():
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alphabet = string.ascii_uppercase if char.isupper() else string.ascii_lowercase
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encrypted_char = alphabet[(a * alphabet.index(char) + b) % len(alphabet)]
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encrypted_text += encrypted_char
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else:
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encrypted_text += char
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return encrypted_text
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# Substitution cipher encryption
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def substitution_cipher_encrypt(text, key):
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encrypted_text = ""
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for char in text:
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if char.isalpha():
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alphabet = string.ascii_uppercase if char.isupper() else string.ascii_lowercase
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substitution_alphabet = str.maketrans(alphabet, key.upper()) if char.isupper() else str.maketrans(alphabet, key.lower())
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encrypted_char = char.translate(substitution_alphabet)
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encrypted_text += encrypted_char
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else:
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encrypted_text += char
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return encrypted_text
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# Transposition cipher encryption
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def transposition_cipher_encrypt(text, key):
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ciphertext = [''] * int(key)
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for column in range(int(key)):
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currentIndex = column
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while currentIndex < len(text):
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ciphertext[column] += text[currentIndex]
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currentIndex += int(key)
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return ''.join(ciphertext)
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def main():
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text = input("Enter the text to encrypt: ")
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# Ask user for the encryption method
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print("Choose an encryption method:")
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print("1. Caesar cipher")
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print("2. Affine cipher")
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print("3. Substitution cipher")
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print("4. Transposition cipher")
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try:
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choice = int(input("Enter your choice (1-4): "))
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except ValueError: #to handle wrong values
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print("Invlaid selection")
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sys.exit(0)
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if choice == 1:
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try:
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shift = int(input("Enter the shift value for Caesar cipher: "))
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encrypted_text = caesar_cipher_encrypt(text, shift)
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print("Caesar cipher (encryption):", encrypted_text)
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except ValueError:
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print("Invalid Input")
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elif choice == 2:
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try:
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a = int(input("Enter the value for 'a' in Affine cipher: "))
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b = int(input("Enter the value for 'b' in Affine cipher: "))
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encrypted_text = affine_cipher_encrypt(text, a, b)
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print("Affine cipher (encryption):", encrypted_text)
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except ValueError:
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print("Invalid Input")
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elif choice == 3:
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key = input("Enter the substitution key: ")
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if len(key)==26:
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encrypted_text = substitution_cipher_encrypt(text, key)
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print("Substitution cipher (encryption):", encrypted_text)
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else:
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print("Key must have the same length as the number of characters in the alphabet (26).")
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elif choice == 4:
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try:
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transpose_key = input("Enter the transposition key (make sure its less than length of stirng): ")
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if int(transpose_key)>len(text):
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print("Key must be less than length of string")
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else:
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encrypted_text = transposition_cipher_encrypt(text, transpose_key)
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print("Transposition cipher (encryption):", encrypted_text)
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except ValueError:
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print("Invalid Input")
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else:
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print("Invalid choice. Please choose a number between 1 and 4.")
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if __name__ == "__main__":
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main()

‎text_encryption/readme.md

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# Encryption Script
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This script allows you to encrypt text using various encryption methods.
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## Installation
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1. Make sure you have Python installed on your system.
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2. Clone this repository or download the script file.
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## Usage
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1. Open a terminal or command prompt.
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2. Navigate to the directory where the script is located.
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3. Run the following command: python script.py
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Follow the prompts to enter the text and choose an encryption method.
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Encryption Methods
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Caesar Cipher
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The Caesar cipher is a substitution cipher where each letter in the plaintext is shifted a certain number of positions down the alphabet.
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To choose the Caesar cipher, enter 1 when prompted.
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Affine Cipher
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The Affine cipher is a substitution cipher that combines the Caesar cipher with multiplication and addition.
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To choose the Affine cipher, enter 2 when prompted.
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Substitution Cipher
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The Substitution cipher is a method of encryption where each letter in the plaintext is replaced by another letter according to a fixed key.
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To choose the Substitution cipher, enter 3 when prompted. Note that the key must have the same length as the number of characters in the alphabet (26).
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Transposition Cipher
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The Transposition cipher is a method of encryption that rearranges the letters of the plaintext to form the ciphertext.
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To choose the Transposition cipher, enter 4 when prompted. You will also be asked to enter a transposition key, which should be less than the length of the text.
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Note: If you enter an invalid choice or provide incorrect input, appropriate error messages will be displayed.
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Example
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Here is an example of running the script:
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Enter the text to encrypt: Hello, World!
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Choose an encryption method:
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1. Caesar cipher
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2. Affine cipher
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3. Substitution cipher
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4. Transposition cipher
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Enter your choice (1-4): 3
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Enter the substitution key: QWERTYUIOPASDFGHJKLZXCVBNM
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Substitution cipher (encryption): ITSSG, KTSSG!

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