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.

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📋 Prerequisites

• Python 3.7 or higher
• cryptography library

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🚀 Installation

Via PyPI (Recommended)

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

pip install fz-decrypt

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 .

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💻 Usage

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

Simple Example

fromfz_decryptimportFileZillaDecryptor, DecryptionError, InvalidDataError# 1. Data from FileZilla sitemanager.xml# These strings can be found in the <Pass> tags and their PubKey Attributexml_pubkey="..."# Base64 String from PubKey=xml_pass_blob="..."# Base64 String from <Pass># 2. The user's master passwordmaster_password="MySecretMasterPassword"try:
# Attempt decryptioncleartext_password=FileZillaDecryptor.decrypt(
master_password,
xml_pubkey,
xml_pass_blob
)
print(f"The decrypted password is: {cleartext_password}")
exceptDecryptionError:
print("Error: The master password is incorrect or the data is corrupt.")
exceptInvalidDataErrorase:
print(f"Error: Invalid data format (Base64 error, etc.): {e}")
exceptExceptionase:
print(f"An unexpected error occurred: {e}")

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📖 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 Attribute of the <Pass> 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.

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🔒 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.

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📄 License

This project is licensed under the MIT License.