A cryptographic key (RSA). The CryptoKey class represents a cryptographic key. Keys can be loaded and saved like any other [Resource]. They can be used to generate a self-signed [X509Certificate] via [method Crypto.generate_self_signed] and as private key in [method StreamPeerSSL.accept_stream] along with the appropriate certificate. Loads a key from [code]path[/code] ("*.key" file). Saves a key to the given [code]path[/code] (should be a "*.key" file).