Apple’s AirDrop is a seamless way to share files between iPhones, iPads, and Macs — but it remains a closed, proprietary protocol. OpenDrop offers a rare, experimental window into how AirDrop really works by reverse-engineering its communication over Apple Wireless Direct Link (AWDL). This Python CLI tool lets you send files and URLs to iOS and macOS devices from Linux or macOS, bypassing Apple’s usual ecosystem lock-in.
what OpenDrop does and how it works
OpenDrop is a command-line interface written in Python that implements the AirDrop protocol by reverse-engineering Apple’s AWDL layer, which is a Wi-Fi peer-to-peer technology exclusive to Apple devices.
AirDrop itself uses AWDL to establish direct Wi-Fi connections between devices for file and URL sharing, coupled with Bluetooth LE for discovery and triggering transfers. OpenDrop focuses on the Wi-Fi side, requiring AWDL support either natively on macOS or via the OWL kernel module on Linux.
The tool supports sending files and URLs to Apple devices, as well as receiving files from them. It also supports “contacts-only” mode by leveraging extracted keychain credentials, mimicking how Apple validates identities for restricted sharing.
Under the hood, OpenDrop handles low-level AWDL packet crafting and parsing, TLS handshake emulation without Apple certificate validation, and payload delivery. It uses Python 3.6+ and depends on a modern libarchive for payload processing.
The project originated from academic research at TU Darmstadt and was published at USENIX Security, making it one of the few open-source implementations shedding light on Apple’s notoriously closed AirDrop internals.
technical strengths and design tradeoffs
OpenDrop’s main technical strength is its detailed reverse-engineering of the AWDL-based AirDrop protocol, including payload classification, TLS handshake emulation, and support for contacts-only mode via keychain credential extraction.
The code demonstrates a deep understanding of Apple’s proprietary protocol stack and Wi-Fi-layer interactions.
It cleverly exploits the AirDrop protocol’s support for URLs as payloads: sending a URL triggers the receiver’s browser to open immediately, revealing how payload types influence client behavior.
This is a subtle but insightful feature that goes beyond mere file transfer.
The codebase, while experimental, is surprisingly clean for a research tool, making it accessible for further experimentation or extension.
That said, there are clear limitations and tradeoffs:
The BLE-based receiver triggering mechanism is unimplemented, so discovery relies on manual or external actions.
Apple certificate validation is skipped, which limits security guarantees and real-world use.
Multi-file sending is unsupported; each send is a single file or URL.
The tool requires AWDL support, which on Linux means running the OWL kernel module, adding complexity.
The security model depends on extracted keychain credentials for contacts-only mode, which is not trivial to obtain.
These tradeoffs reflect the complexity of reverse-engineering a closed protocol and the challenges of replicating Apple’s full security posture.
quick start
Requirements
To achieve compatibility with Apple AirDrop, OpenDrop requires the target platform to support a specific Wi-Fi link layer. In addition, it requires Python >=3.6 as well as several libraries.
Apple Wireless Direct Link. As AirDrop exclusively runs over Apple Wireless Direct Link (AWDL), OpenDrop is only supported on macOS or on Linux systems running an open re-implementation of AWDL such as OWL.
Libraries. OpenDrop relies on a current version of libarchive. macOS ships with a rather old version, so you will need to install a newer version, for example, via Homebrew:
brew install libarchive
OpenDrop automatically sets DYLD_LIBRARY_PATH to look for the Homebrew version. You may need to update the variable yourself if you install the libraries differently.
Linux distributions should ship with more up-to-date versions, so this won’t be necessary.
Installation
Installation of the Python package release is straightforward using pip3:
pip3 install opendrop
You can also install the current development version by first cloning this repository, and then installing it via pip3:
git clone https://github.com/seemoo-lab/opendrop.git
pip3 install ./opendrop
verdict
OpenDrop is a valuable tool for security researchers, reverse engineers, and advanced users interested in the internals of Apple’s AirDrop protocol. Its ability to send files and URLs cross-platform using AWDL is impressive given the closed nature of the protocol.
However, this is not a plug-and-play file sharing solution for everyday users. It requires a compatible platform with AWDL support (macOS or Linux with OWL), modern dependencies, and some comfort with Python CLI tools.
The absence of BLE-based discovery and certificate validation means it remains experimental and mostly suited for research and protocol experimentation.
If your work or curiosity intersects with Apple wireless protocols or peer-to-peer file sharing, OpenDrop offers an open-source foothold worth exploring. For production or casual use, the limitations and setup complexity might be prohibitive.
Related Articles
- pymobiledevice3: a pure Python iOS device communication stack — pymobiledevice3 reimplements the entire iOS device communication stack in pure Python, replacing C-based tools. It suppo
- Feather: on-device iOS app sideloading with certificate-paired signing — Feather is an open-source iOS app manager enabling on-device IPA signing using Apple Developer certificate pairs, reimpl
- OpenPods: reverse engineering AirPods battery monitoring on Android — OpenPods is an Android app that locally monitors AirPods and Beats battery levels by decoding Apple’s proprietary Blueto
- Sliver: a cryptographically unique adversary emulation framework with multi-protocol C2 — Sliver uses compile-time asymmetric encryption keys to generate unique implant binaries and supports multiple C2 protoco
- Bluehood: passive Bluetooth scanning and presence pattern analysis on Linux — Bluehood passively scans BLE and Classic Bluetooth devices, tracks presence patterns, and reveals limits of MAC randomiz
→ GitHub Repo: seemoo-lab/opendrop ⭐ 9,630 · Python