A put in OpenDHT takes the following five arguments:
* application: string
* client_library: string
* key: byte array, maximum 20 bytes
* value: byte array, maximum 1024 bytes
* ttl_sec: four-byte integer, maximum value 604,800 seconds (one week)
* secret_hash: SHA-1 hash of a secret that can be used to remove the put later (optional)