We are glad that our solution is discussed in depth by community experts.
This is the intention from the beginning - to open technical details of our design on our site and in the near future all SW source code, to the community review (especially harsh ones). We want to create the best solution for bitcoin storage and to answer any shortcomings before the product is ready for delivery.
As for the issues raised by Greg Maxwell:
- Until recently we were very focused on the system hardware and software design with the emphasis on modular easy to use architecture. We are using Trezor crypto libraries for now in the internal system tests, as it is embedded-friendly. Before releasing the product we were planning to review the crypto quality with the help of the community and achieve the best implementation. Greg's insight sharpens the issues with this library and great need for improvement. We intend to use EliptiBox by ourselves and do not want to "leak" money.
- We spent a lot of time to plan highly energy-efficient power network. FPGA, BT modem and other components can be turned completely off to conserve battery. The FPGA is turned on only when needed to communicate transaction data for signing, so that the average power over time is negligible. Our power design allows the product to spend 2 years on standby or to sign 1000 transaction without charging.
- PCB ground:
Board design complies to the strict EM field leakage prevention, so that our board has 6 layers with complete ground layer to close the loop together with the metal RF cages.
- Firewall:
We've analysed many different approaches to secure decoupling between crypto HW and external world (including audio) and chose the FPGA as the most versatile and safe solution to prevent remote attacks on the HW. To ensure this, only RED crypto controller can load bitstream to FPGA. Remote attacker can not access the RED controller code through the firewall and can not change the bitstream.
Moreover, we'll offer the HW as a development platform with complete description, so that anyone can play with it and audit it's features.
Crypto algorithm has a crucial part in overall security. This is the reason we are going open source for feedback and swift adoption of all changes.
We are always glad to read any comments and advice and implement the resulting improvements to be shared with the community.
EliptiBox Team
www.eliptibox.com