Phantomdrive Open-Source USB Drive Conceals Encrypted Storage to Resist Coercion

Developer Ryan Walker has created Phantomdrive, an open-source USB storage device designed to protect users against forced decryption demands in jurisdictions with weak privacy laws. Unlike standard hidden-volume solutions such as VeraCrypt, Phantomdrive aims to prevent authorities from even detecting the existence of additional encrypted space.

The device presents itself to the host operating system as a conventional 8 GB drive upon first connection. Any data written to this visible area remains unencrypted until the user creates a text file containing the exact string password: PUTYOURPASSWORDHERE. The firmware then triggers a re-enumeration that exposes the hidden, AES-encrypted partition while simultaneously encrypting the previously visible area on the fly.

Hardware design centers on the CH569 microcontroller from the same family as the widely used CH340 USB-to-serial bridge. The chip provides native USB 3.0, SD/eMMC interfacing, and a hardware encryption block supporting the Chinese SM4 algorithm alongside standard AES operations. Storage is provided by an SD card rather than eMMC due to current pricing pressures; the entire assembly is sealed with epoxy resin so that physical access requires destruction of the enclosure.

Key derivation uses a per-device salt extracted from the USB serial number (for example, Phantomdrive:34FC1FA7145467F7) combined with 100,000 iterations of SHA-256. This approach eliminates rainbow-table attacks across multiple devices and raises the cost of brute-force attempts. The developer deliberately avoided memory-hard functions such as Argon2 because the limited RAM on the CH569 would make unlock times exceed acceptable limits.

Encryption defaults to AES-CTR mode, achieving approximately 9 MB/s write and 20 MB/s read throughput. AES-XTS is also implemented for users who prioritize resistance to ciphertext manipulation over speed, although it reduces performance to roughly 6 MB/s writes and 10 MB/s reads. Both modes were validated through functional tests and cross-checked against the OpenSSL reference implementation.

The firmware continuously inspects raw USB WRITE10 commands for the trigger string without interpreting any file system. When detected, the password is copied into RAM, the buffer is zeroed to prevent the secret from reaching the media, and the device switches partitions. Users are warned that high volumes of random data on the visible partition could theoretically produce a false-positive match.

All schematics, firmware sources, and mechanical files are released publicly, along with the supporting libraries originally developed for the hydrausb3 project. Pre-order pages are already live for those wishing to obtain early hardware units.