Anigma SCI Design Overview

The Anigma SCI uses a segregated systems architecture to improve security. It is divided into an "Internal" and "External" core, with a user-controlled physical switch mediating data flow from the External to the Internal sides. All external interfaces to the untrusted world are managed by the External subsystem. User input/output, cryptography, data storage and control of the system is managed by the Internal subsystem.

Logical Systems Architecture

Internal Subsystem

• Core MCU: ATSAMD51, Arm Cortex M4
• Key Pad, directly wired to GPIO Pins
• SPI Display module, wired for write-only.
• Real Time Clock IC w/ Battery back-up
• FRAM non-volatile data storage
• Optiga Trust M security IC
• External Rx connection mediated by physical switch

External Subsystem

• Core MCU: ATSAMD21, Arm Cortex M0
• Core MCU handles USB HID connection with host computer.
• Infrared serial port for non-RF SCI-to-SCI data exchange.
• Hot-plug I2C QWIIC connector for devices such as QR Code reader

External Interfaces

• External subsystem presents as USB composite profile with keyboard and serial devices
• External MCU buffers message packets from host or devices.
• Ingest of message packets from External to Internal system only on user initiated command from Internal subsystem.

Host Software

• Host only requires standard built-in drivers for keyboard and USB serial devices (all current operating systems).
• "Helper" app on host can be used for integration into browser or chat apps.
• A web browser extension supports integration to mitigate common phishing password attacks.