Improve key exchange by having the server maintain a pool of RSA keys

[nuvious]

Current implementation has the server generate an RSA key after initial receipt of a connection from a new client. This offsets the client and server key exchange by 8 bytes requiring the server to initially set its host id to a random 8 byte value and the client having to send an extra random 8 byte value. There is also a latency cost in the server generating an RSA key during the initial connection which could be detected.

Instead, have the server maintain a pool of RSA keys. When a new client connects it should pull from the pool of keys and use the N modulus to set the initial host-id for the connection. After enough 8 byte segments of the N modulus are transmitted both the client and server send a keep-alive command to confirm receipt and establishment of the covert channel connection. For non-covert channel connections the server will not receive the expected keep alive message and can mark the client as a non-covert channel client and issue random connection ids for subsequent connections.

Using a pool of keys would allow an 8 byte reduction in the total key exchange transactions and the pool of RSA keys can be maintained via a separate key generation thread that keeps a queue filled to a specified number of keys desired. This would also eliminate any latency incurred by generating the key upon connection.