Added a new and innovative Project AES File Encryption Tool

AswinPKumar01 · AswinPKumar01 · commit a458115f9696 · 2024-10-05T14:46:01.000+05:30
diff --git a/A/AES-File-Encryption-Tool/README.md b/A/AES-File-Encryption-Tool/README.md
@@ -0,0 +1,87 @@
+# AES Encryption Tool
+
+This tool provides a simple interface to encrypt and decrypt files using the AES (Advanced Encryption Standard) encryption algorithm. It uses the AES-CBC mode for encryption, ensuring that your data remains secure and private. A password-based key derivation function (PBKDF2 with HMAC-SHA256) is used to derive the encryption key from the provided password, adding another layer of security.
+
+## Features
+
+- **Encrypt Files**: Securely encrypt any file with a password.
+- **Decrypt Files**: Decrypt previously encrypted files using the same password.
+- **Automatic Padding**: Automatically handles file padding to ensure proper encryption even for files that are not a multiple of the AES block size.
+- **Salt and IV Generation**: Generates a random salt and initialization vector (IV) for each encryption to enhance security.
+
+## Installation
+
+### Prerequisites:
+
+1. Python 3.x
+2. `cryptography` package
+
+### To install the required package:
+
+```bash
+pip install cryptography
+```
+
+## Usage
+
+### Command-line Arguments
+
+- `mode`: Choose between `encrypt` or `decrypt` mode.
+- `input_file`: The path to the file you want to encrypt or decrypt.
+- `output_file` (optional): The desired path for the encrypted or decrypted output file. If not provided, the tool will generate a default name:
+  - For encryption: `input_file.enc`
+  - For decryption: If the input file ends with `.enc`, it will remove this extension, otherwise it appends `.dec`.
+
+### Encrypting a File
+
+```bash
+python aes_tool.py encrypt <input_file> <output_file>
+```
+
+**Example:**
+
+```bash
+python aes_tool.py encrypt example.txt
+```
+
+This will prompt you for a password and create an encrypted file called `example.txt.enc`.
+
+### Decrypting a File
+
+```bash
+python aes_tool.py decrypt <input_file> <output_file>
+```
+
+**Example:**
+
+```bash
+python aes_tool.py decrypt example.txt.enc
+```
+
+This will prompt you for the password and decrypt the file to `example.txt`.
+
+### Important Notes:
+
+- You must remember the password used for encryption. The same password is required for decryption.
+- If you provide an incorrect password during decryption, the tool will notify you of the failure and delete any incomplete output files to prevent corruption.
+
+## How It Works
+
+1. **Encryption:**
+
+   - The tool generates a random 16-byte salt and initialization vector (IV).
+   - The salt is used with PBKDF2HMAC (HMAC-SHA256) to derive a cryptographic key from the password.
+   - AES encryption (in CBC mode) is applied to the input file data.
+   - The encrypted file contains the salt, IV, and the encrypted data.
+
+2. **Decryption:**
+   - The tool reads the salt and IV from the encrypted file.
+   - It derives the cryptographic key using the same password-based key derivation function (PBKDF2HMAC).
+   - AES decryption is applied, and the original file content is recovered.
+
+## Author
+
+- **Name**: Aswin P Kumar
+- **GitHub**: [AswinPKumar01](https://github.com/AswinPKumar01)
+
+---
diff --git a/A/AES-File-Encryption-Tool/aes_tool.py b/A/AES-File-Encryption-Tool/aes_tool.py
@@ -0,0 +1,128 @@
+import os
+import sys
+import argparse
+import getpass
+from cryptography.hazmat.backends import default_backend
+from cryptography.hazmat.primitives import hashes, padding as sym_padding
+from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
+from cryptography.hazmat.primitives.kdf.pbkdf2 import PBKDF2HMAC
+
+def derive_key(password, salt, key_size):
+    # Derive a cryptographic key from the password
+    kdf = PBKDF2HMAC(
+        algorithm=hashes.SHA256(),
+        length=key_size // 8,
+        salt=salt,
+        iterations=100000,
+        backend=default_backend()
+    )
+    key = kdf.derive(password.encode())
+    return key
+
+def encrypt_file(input_file, output_file, password):
+    # Generate salt and IV
+    salt = os.urandom(16)
+    iv = os.urandom(16)
+
+    # Derive key
+    key = derive_key(password, salt, 256)
+
+    # Initialize cipher
+    cipher = Cipher(algorithms.AES(key), modes.CBC(iv), backend=default_backend())
+    encryptor = cipher.encryptor()
+
+    # Read input file and encrypt
+    with open(input_file, 'rb') as f_in, open(output_file, 'wb') as f_out:
+        # Write salt and IV to the output file
+        f_out.write(salt)
+        f_out.write(iv)
+
+        # Read the file in chunks
+        while True:
+            chunk = f_in.read(1024)
+            if len(chunk) == 0:
+                break
+            elif len(chunk) % 16 != 0:
+                padder = sym_padding.PKCS7(128).padder()
+                chunk = padder.update(chunk) + padder.finalize()
+            encrypted_chunk = encryptor.update(chunk)
+            f_out.write(encrypted_chunk)
+        # Finalize encryption
+        f_out.write(encryptor.finalize())
+
+    print(f"File encrypted successfully: {output_file}")
+
+def decrypt_file(input_file, output_file, password):
+    with open(input_file, 'rb') as f_in:
+        # Read salt and IV from the input file
+        salt = f_in.read(16)
+        iv = f_in.read(16)
+
+        # Derive key
+        key = derive_key(password, salt, 256)
+
+        # Initialize cipher
+        cipher = Cipher(algorithms.AES(key), modes.CBC(iv), backend=default_backend())
+        decryptor = cipher.decryptor()
+
+        # Prepare to write decrypted data
+        try:
+            with open(output_file, 'w+b') as f_out:
+                # Read the encrypted file in chunks
+                while True:
+                    chunk = f_in.read(1024)
+                    if len(chunk) == 0:
+                        break
+                    decrypted_chunk = decryptor.update(chunk)
+                    f_out.write(decrypted_chunk)
+                # Finalize decryption
+                decrypted_chunk = decryptor.finalize()
+                f_out.write(decrypted_chunk)
+                # Remove padding
+                f_out.seek(0)
+                data = f_out.read()
+                unpadder = sym_padding.PKCS7(128).unpadder()
+                data = unpadder.update(data) + unpadder.finalize()
+                f_out.seek(0)
+                f_out.write(data)
+                f_out.truncate()
+            print(f"File decrypted successfully: {output_file}")
+        except Exception as e:
+            print("Decryption failed. Incorrect password or corrupted file.")
+            # Ensure the file is closed before deletion
+            if not f_out.closed:
+                f_out.close()
+            if os.path.exists(output_file):
+                os.remove(output_file)
+
+
+def main():
+    parser = argparse.ArgumentParser(description='AES File Encryption Tool')
+    parser.add_argument('mode', choices=['encrypt', 'decrypt'], help='Mode of operation')
+    parser.add_argument('input_file', help='Input file path')
+    parser.add_argument('output_file', nargs='?', help='Output file path')
+    args = parser.parse_args()
+
+    if not os.path.exists(args.input_file):
+        print("Input file does not exist.")
+        sys.exit(1)
+
+    if not args.output_file:
+        # Generate default output file name
+        if args.mode == 'encrypt':
+            args.output_file = args.input_file + '.enc'
+        else:
+            if args.input_file.endswith('.enc'):
+                args.output_file = args.input_file[:-4]
+            else:
+                args.output_file = args.input_file + '.dec'
+
+    password = getpass.getpass(prompt='Enter password: ')
+
+    if args.mode == 'encrypt':
+        encrypt_file(args.input_file, args.output_file, password)
+    else:
+        decrypt_file(args.input_file, args.output_file, password)
+
+if __name__ == '__main__':
+    main()
