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_certificate] and as private key in [method StreamPeerSSL.accept_stream] along with the appropriate certificate. Return [code]true[/code] if this CryptoKey only has the public part, and not the private one. Loads a key from [code]path[/code]. If [code]public_only[/code] is [code]true[/code], only the public key will be loaded. [b]Note:[/b] [code]path[/code] should be a "*.pub" file if [code]public_only[/code] is [code]true[/code], a "*.key" file otherwise. Loads a key from the given [code]string[/code]. If [code]public_only[/code] is [code]true[/code], only the public key will be loaded. Saves a key to the given [code]path[/code]. If [code]public_only[/code] is [code]true[/code], only the public key will be saved. [b]Note:[/b] [code]path[/code] should be a "*.pub" file if [code]public_only[/code] is [code]true[/code], a "*.key" file otherwise. Returns a string containing the key in PEM format. If [code]public_only[/code] is [code]true[/code], only the public key will be included.