sequoia-keystore

Sequoia's private key store.

This project implements a private key store for Sequoia. A private key store mediates applications' access to private keys, and offers three major advantages relative to every application accessing the keys or HSMs directly:

• A private key store is in a separate address space. This means that private keys that are in memory are in a different address space from the application. This was underlying cause of the Heartbleed vulnerability.

• A private key store can provide a uniform interface for accessing keys stored on different backends, e.g., an in-memory key, a key on a smart card, or a key on a remote computer, which is accessed via ssh. This simplifies applications.

• This architecture simplifies sharing private key material among multiple applications. Only the private key store needs to worry about managing the private key material, which improves security. And, when a user unlocks a key in one application, it is potentially unlocked in all applications, which improves usability.

Although the key store can run as a separate server, sometimes it is useful to co-locate it. This is useful to increase robustness, e.g., the key store is not running, and can't be started for some reason. And, it allows the key store to be used in places where starting processes is not easy or not desirable, like in an initrd.

The private key store uses a device-driver style architecture. The sequoia-keystore-backend crate defines a trait that different backends implement. Currently, backends are added at compile time.

The sequoia-keystore-softkeys backend is an example of a backend. It supports soft keys, i.e., in-memory keys.