Trait Backend 

pub trait Backend: Send + Sync {
    // Required methods
    fn name(&self) -> &str;
    fn provider(&self) -> &str;
    fn fingerprint(&self) -> String;

    // Provided methods
    fn as_keystore_mut(&mut self) -> Option<&mut dyn KeyStoreBackend> { ... }
    fn as_sign_mut(&mut self) -> Option<&mut dyn SignBackend> { ... }
    fn as_verify_mut(&mut self) -> Option<&mut dyn VerifyBackend> { ... }
    fn as_attest_mut(&mut self) -> Option<&mut dyn AttestationBackend> { ... }
    fn as_piv_mut(&mut self) -> Option<&mut dyn PivBackend> { ... }
    fn as_yubikey_mut(&mut self) -> Option<&mut dyn YubikeyBackend> { ... }
    fn as_transport_mut(&mut self) -> Option<&mut dyn KeyTransportBackend> { ... }
    fn as_certstore_mut(&mut self) -> Option<&mut dyn CertStoreBackend> { ... }
    fn as_random_mut(&mut self) -> Option<&mut dyn RandomBackend> { ... }
    fn as_pkcs11_mut(&mut self) -> Option<&mut dyn Pkcs11Backend> { ... }
    fn as_pkcs11_admin_mut(&mut self) -> Option<&mut dyn Pkcs11AdminBackend> { ... }
    fn as_tpm_mut(&mut self) -> Option<&mut dyn TpmBackend> { ... }
}

Core trait that all backends must implement.

Provides identity and fingerprinting for audit trails.

Capability downcasting

Rust does not allow downcasting from dyn Backend to dyn KeyStoreBackend (or any other subtrait) without explicit support. The as_*_mut methods implement this pattern manually: a backend returns Some(self) for each capability it supports, and None for those it does not.

Use the backend_capabilities! macro to generate these methods without boilerplate.

Required Methods

fn name(&self) -> &str

Backend name (unique identifier within a ceremony).

fn provider(&self) -> &str

Backend provider name (e.g., “software”, “yubikey”, “pkcs11”).

fn fingerprint(&self) -> String

Fingerprint for audit evidence.

Format examples:

• Software: "software-backend=mybackend"
• YubiKey: "yubikey-serial=12345678+firmware=5.7.1"
• PKCS#11: "pkcs11-module=/usr/lib/softhsm2.so+slot=0"

Provided Methods

fn as_keystore_mut(&mut self) -> Option<&mut dyn KeyStoreBackend>

Not supported by this backend, always returns None.

fn as_sign_mut(&mut self) -> Option<&mut dyn SignBackend>

Not supported by this backend, always returns None.

fn as_verify_mut(&mut self) -> Option<&mut dyn VerifyBackend>

Not supported by this backend, always returns None.

fn as_attest_mut(&mut self) -> Option<&mut dyn AttestationBackend>

Not supported by this backend, always returns None.

fn as_piv_mut(&mut self) -> Option<&mut dyn PivBackend>

Not supported by this backend, always returns None.

fn as_yubikey_mut(&mut self) -> Option<&mut dyn YubikeyBackend>

Not supported by this backend, always returns None.

fn as_transport_mut(&mut self) -> Option<&mut dyn KeyTransportBackend>

Not supported by this backend, always returns None.

fn as_certstore_mut(&mut self) -> Option<&mut dyn CertStoreBackend>

Not supported by this backend, always returns None.

fn as_random_mut(&mut self) -> Option<&mut dyn RandomBackend>

Not supported by this backend, always returns None.

fn as_pkcs11_mut(&mut self) -> Option<&mut dyn Pkcs11Backend>

Not supported by this backend, always returns None.

fn as_pkcs11_admin_mut(&mut self) -> Option<&mut dyn Pkcs11AdminBackend>

Not supported by this backend, always returns None.

fn as_tpm_mut(&mut self) -> Option<&mut dyn TpmBackend>

Not supported by this backend, always returns None.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors