Signet High-capacity

An all-in-one encrypted USB flash drive, two-factor authentication token, and password manager

Oct 11, 2019

Personal Information Database

We’ve studied the results of the encryption engine survey we posted earlier this week and determined our initial approach to implementing the encryption features. The survey showed that users had the greatest interest in:

Our first step will be to integrate these features into our GUI and command line tool. This may not be the way most users will interact with the features but it’s good for testing and implementation flexibility. Then we will move on to porting Gnuk into the Signet HC firmware for GnuPG (GPG) integration. We will release first for GNU/Linux and then add support for other platforms shortly after.

For the long term we would like to directly integrate with GPG so that a password can unlock Signet HC instead of the PIN codes used by the smart card specification. Until we can integrate such a change into a major GPG release users will need to unlock their Signet HC with our GUI or command line tool before using it with GPG.

In-Depth Look: Personal Information Database

Signet HC’s personal information database helps users manage their data through two layers of software:

Database Structure

Signet HC’s personal information database was designed to store any kind of sensitive user data for access within the client GUI or the client’s browser plugin. All data except files is stored in the personal information database, including two-factor authentication data and public/private key pairs. The database is stored in a region of the microcontroller’s internal flash memory to make it difficult to access if the microcontroller’s security protections are enabled. The database is a collection of entries each of which consist of the following:

When the client starts up it requests all of the unmasked data from all of the entries in the database. This is the data that is not particularly sensitive. The client uses this data to allow the user to search and sort database entries. The user can later request to view the full contents of specific entries, which can be done after pressing the device button.

Password Management

The use case we most commonly discuss for the database is password management. At the hardware level, account entries are no different from other entries. What differentiates them in the client is that the client has specialized features for them whereas user created data types have a generic GUI. Here are some of the password management specific features:

User Defined Fields

The Signet client has three predefined data types:

The accounts and bookmarks types contain the kinds of fields you would expect. It is possible to add user-defined fields to account data however. One common use is to include answers to account security questions.

The miscellany data type has no pre-defined fields. Instead a miscellaneous entry only has a name and a variable number of user added fields:

In addition to allowing the addition of individual fields it is possible to create a new data type that has a set of user specified required fields but also supports the addition of a variable number of extra fields to specific entries.


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