FeatherDuster is a cryptanalysis tool designed to identify and exploit weaknesses in cryptographic systems. The tool automates the process of analyzing ciphertext files to detect vulnerable encryption implementations and attempts to break them through various cryptanalytic techniques. The framework includes Cryptanalib, which serves as the underlying cryptographic analysis library that can be used independently of the main FeatherDuster interface. This modular approach allows users to leverage the cryptanalytic capabilities in custom implementations or integrate them into other security testing workflows. FeatherDuster accepts multiple ciphertext files as input and applies automated analysis techniques to identify potential vulnerabilities in the cryptographic implementation. The tool focuses on detecting common cryptographic weaknesses and misconfigurations that may allow for successful cryptanalytic attacks. The project is currently in beta release status, indicating ongoing development and potential for bugs or incomplete features. Users can run the tool through Python scripts or use the installed command-line interface to analyze target ciphertext files.