Implement custom VIDs

The SecureStore, exposed as the primary API for the TSP Rust library, accepts adding private and verified VIDs.

A private VID is an identity that contains private key material to sign and decrypt messages.

A verified VID is an identity that only contains public key material to encrypt data and verify signatures. In the context of TSP Rust, a verified VID should only be constructed if it is resolved and verified. What verification means depends on the type of VID.

Traits

The SecureStore accepts any private or verified VID that implements the PrivateVid and VerifiedVid traits, respectively. Each of these traits defines methods to get the VID string itself and methods to get the key material:

#![allow(unused)]
fn main() {
pub trait VerifiedVid: Send + Sync {
    /// A identifier of the Vid as bytes (for inclusion in TSP packets)
    fn identifier(&self) -> &str;

    /// The transport layer endpoint in the transport layer associated with this Vid
    fn endpoint(&self) -> &url::Url;

    /// The verification key that can check signatures made by this Vid
    fn verifying_key(&self) -> &PublicVerificationKeyData;

    /// The encryption key associated with this Vid
    fn encryption_key(&self) -> &PublicKeyData;
}

pub trait PrivateVid: VerifiedVid + Send + Sync {
    /// The PRIVATE key used to decrypt data
    fn decryption_key(&self) -> &PrivateKeyData;

    /// The PRIVATE key used to sign data
    fn signing_key(&self) -> &PrivateSigningKeyData;
}
}

Any Rust type that implements one of these traits can be added to the store (either AsyncSecureStore or the SecureStore).