Namespace iText.Kernel.Crypto.Securityhandler Classes PubKeySecurityHandler PubSecHandlerUsingAes128 PubSecHandlerUsingAes256 PubSecHandlerUsingStandard128 PubSecHandlerUsingStandard40 PublicKeyRecipient SecurityHandler StandardHandlerUsingAes128 StandardHandlerUsingAes256 StandardHandlerUsingStandard128 StandardHandlerUsingStandard40 StandardSecurityHandler UnsupportedSecurityHandlerException