FileZilla Decryptor Lib (fz-decrypt)

A lightweight, robust Python library for decrypting FileZilla Server passwords protected by a master password (sitemanager.xml).

This library implements FileZilla's cryptography logic (PBKDF2, X25519 Key Exchange, AES-GCM) in pure Python.

📋 Prerequisites

• Python 3.7 or higher
• cryptography library

🚀 Installation

Via PyPI (Recommended)

You can easily install the library from the Python Package Index (PyPI):

pip install fz-decrypt

(Note: Replace fz-decrypt with your actual package name if different)

From Source (Development)

If you want to modify the code or install a local version:

1. Clone the repository or download the source.

2. Navigate to the directory containing pyproject.toml.

3. Run:

   pip install .
   

For development (changes are reflected immediately):

pip install -e .

💻 Usage

The library provides a main class FileZillaDecryptor. It requires no instantiation; the decrypt method is a static/class method.

Simple Example

from fz_decrypt import FileZillaDecryptor, DecryptionError, InvalidDataError

# 1. Data from FileZilla sitemanager.xml
# These strings can be found in the <PubKey> and <Pass> tags
xml_pubkey = "..."       # Base64 String from <PubKey>
xml_pass_blob = "..."    # Base64 String from <Pass>

# 2. The user's master password
master_password = "MySecretMasterPassword"

try:
    # Attempt decryption
    cleartext_password = FileZillaDecryptor.decrypt(
        master_password,
        xml_pubkey,
        xml_pass_blob
    )
    print(f"The decrypted password is: {cleartext_password}")

except DecryptionError:
    print("Error: The master password is incorrect or the data is corrupt.")

except InvalidDataError as e:
    print(f"Error: Invalid data format (Base64 error, etc.): {e}")

except Exception as e:
    print(f"An unexpected error occurred: {e}")

📖 API Reference

FileZillaDecryptor.decrypt(master_password, xml_pubkey, xml_pass)

Decrypts a password using the FileZilla algorithm.

Parameters:

• master_password (str): The master password entered when starting FileZilla.
• xml_pubkey (str): The content of the <PubKey> tag from the XML file (Base64 encoded).
• xml_pass (str): The content of the <Pass> tag from the XML file (Base64 encoded).

Returns:

• str: The decrypted password in cleartext.

Exceptions:

• DecryptionError: Raised if the master password is incorrect (AES-GCM Tag Mismatch).
• InvalidDataError: Raised if the Base64 strings are invalid or the blobs have an incorrect length.

🔒 Security Note

This tool is intended for recovering your own passwords. Please handle decrypted credentials responsibly. Never store passwords unencrypted in text files if it can be avoided.

📄 License

This project is licensed under the MIT License.