//! For storing transferable public keys.//!//! The key store stores transferable public keys (TPKs) using an//! arbitrary label. Stored keys are automatically updated from//! remote sources. This ensures that updates like new subkeys and//! revocations are discovered in a timely manner.//!//! # Security considerations//!//! Storing public keys potentially leaks communication partners.//! Protecting against adversaries inspecting the local storage is out//! of sc