update file encryption tutorial to add encryption with password

x4nth055 · x4nth055 · commit c8928c2c6de0 · 2022-06-21T11:29:03.000+01:00
diff --git a/ethical-hacking/file-encryption/crypt_password.py b/ethical-hacking/file-encryption/crypt_password.py
@@ -0,0 +1,124 @@
+import cryptography
+from cryptography.fernet import Fernet
+from cryptography.hazmat.primitives.kdf.scrypt import Scrypt
+
+import secrets
+import base64
+import getpass
+
+
+def generate_salt(size=16):
+    """Generate the salt used for key derivation, 
+    `size` is the length of the salt to generate"""
+    return secrets.token_bytes(size)
+
+
+def derive_key(salt, password):
+    """Derive the key from the `password` using the passed `salt`"""
+    kdf = Scrypt(salt=salt, length=32, n=2**14, r=8, p=1)
+    return kdf.derive(password.encode())
+
+
+def load_salt():
+    # load salt from salt.salt file
+    return open("salt.salt", "rb").read()
+
+
+def generate_key(password, salt_size=16, load_existing_salt=False, save_salt=True):
+    """
+    Generates a key from a `password` and the salt.
+    If `load_existing_salt` is True, it'll load the salt from a file
+    in the current directory called "salt.salt".
+    If `save_salt` is True, then it will generate a new salt
+    and save it to "salt.salt"
+    """
+    if load_existing_salt:
+        # load existing salt
+        salt = load_salt()
+    elif save_salt:
+        # generate new salt and save it
+        salt = generate_salt(salt_size)
+        with open("salt.salt", "wb") as salt_file:
+            salt_file.write(salt)
+    # generate the key from the salt and the password
+    derived_key = derive_key(salt, password)
+    # encode it using Base 64 and return it
+    return base64.urlsafe_b64encode(derived_key)
+
+
+def encrypt(filename, key):
+    """
+    Given a filename (str) and key (bytes), it encrypts the file and write it
+    """
+    f = Fernet(key)
+    with open(filename, "rb") as file:
+        # read all file data
+        file_data = file.read()
+    # encrypt data
+    encrypted_data = f.encrypt(file_data)
+    # write the encrypted file
+    with open(filename, "wb") as file:
+        file.write(encrypted_data)
+
+
+def decrypt(filename, key):
+    """
+    Given a filename (str) and key (bytes), it decrypts the file and write it
+    """
+    f = Fernet(key)
+    with open(filename, "rb") as file:
+        # read the encrypted data
+        encrypted_data = file.read()
+    # decrypt data
+    try:
+        decrypted_data = f.decrypt(encrypted_data)
+    except cryptography.fernet.InvalidToken:
+        print("Invalid token, most likely the password is incorrect")
+        return
+    # write the original file
+    with open(filename, "wb") as file:
+        file.write(decrypted_data)
+    print("File decrypted successfully")
+
+
+if __name__ == "__main__":
+    import argparse
+    parser = argparse.ArgumentParser(description="File Encryptor Script with a Password")
+    parser.add_argument("file", help="File to encrypt/decrypt")
+    parser.add_argument("-s", "--salt-size", help="If this is set, a new salt with the passed size is generated",
+                        type=int)
+    parser.add_argument("-e", "--encrypt", action="store_true",
+                        help="Whether to encrypt the file, only -e or -d can be specified.")
+    parser.add_argument("-d", "--decrypt", action="store_true",
+                        help="Whether to decrypt the file, only -e or -d can be specified.")
+
+    args = parser.parse_args()
+    file = args.file
+
+    if args.encrypt:
+        password = getpass.getpass("Enter the password for encryption: ")
+    elif args.decrypt:
+        password = getpass.getpass("Enter the password you used for encryption: ")
+
+    if args.salt_size:
+        key = generate_key(password, salt_size=args.salt_size, save_salt=True)
+    else:
+        key = generate_key(password, load_existing_salt=True)
+
+    encrypt_ = args.encrypt
+    decrypt_ = args.decrypt
+
+    if encrypt_ and decrypt_:
+        raise TypeError("Please specify whether you want to encrypt the file or decrypt it.")
+    elif encrypt_:
+        encrypt(file, key)
+    elif decrypt_:
+        decrypt(file, key)
+    else:
+        raise TypeError("Please specify whether you want to encrypt the file or decrypt it.")
+
+    
+
+    
+
+
