A responder device receives, from an initiator device, a request to initiate a cryptographic tunnel between the initiator device and the responder device. The responder device does not include a static private key to be used in an asymmetric cryptography algorithm when establishing the tunnel. The responder device transmits a request to a key server that has access to the static private key and receives a response that is based on at least a result of at least one cryptographic operation using the static private key. The responder device receives from the key server, or generates, a transport key(s) for the responder device to use for sending and receiving data on the cryptographic tunnel. The responder device transmits a response to the initiator device that includes information for the initiator device to generate a transport key(s) that it is to use for sending and receiving data on the cryptographic tunnel.