Although we have talked at length about the Lattice1, we have not yet given an in-depth view of its companion — the SafeCard. This article will attempt to outline our vision for the SafeCard as both a cold storage option and as a mechanism to scale public blockchain networks.Background
The SafeCard is meant to be a PIN protected, unpowered physical key store. This allows storage of digital secrets offline, but also gives a familiar experience of spending money with a chip card.
GridPlus is using the Status Keycard Applet as a template for the SafeCard Applet. We are also using the accompanying Keycard SDK. As such, we are designing the SafeCard to be at least partially interoperable with the Status Keycard.The SafeCard applet was developed using Status’ Keycard Applet and SDK Unique Features
Although the SafeCard applet is a fork of the Status Keycard applet, there are a few differences that we have implemented:1. Master seeds are stored on the card and may (optionally) be exported
This option is declared when the seed is generated or loaded and may not be changed once set. If the user wishes to export a card’s seed, an interface must establish a secure connection with the card and pass the correct PIN to export the seed. If the user chose “no” to exportability when the seed was loaded/generated, the seed cannot ever be exported from the SafeCard.
Status does not currently store or allow export of master seeds (instead it stores the parent private key, a derivative of the master seed). This is likely because their card’s main interface is near field communication (NFC) — NFC is known to be an insecure means of communication, though it may be acceptable for a user who is spending small amounts of money on the go or utilizing a card for 2FA. By contrast, the GridPlus SafeCard is designed to interface with the Lattice1, which is contact-only and draws exclusively secure screens (i.e. powered...