-This payload is OPTIONAL and can be used to send private message
-key between two clients in the network. The packet is secured with
-normal session keys. By default private messages are encrypted
-with session keys, and with this payload it is possible to set
-private key for private message encryption between two clients.
-
-The receiver of this payload SHOULD verify for example from user
-whether user want to receive private message key. Note that there
-are other, more secure ways of exchanging private message keys in
-the SILC network. Instead of sending this payload it is possible to
-negotiate the private message key with SKE protocol using the Key
-Agreement payload directly peer to peer, see section 2.3.20.
+This payload is OPTIONAL and can be used to indicate that a static
+or pre-shared key should be used in the private message communication
+to protect the messages. The actual key material has to be sent
+outside the SILC network, or it has to be a static or pre-shared key.
+The sender of this packet is considered to be the initiator and the
+receiver the responder when processing the raw key material as
+described in the section 4.6 in [SILC1] and in the section 2.3 in
+[SILC3].
+
+Note that it is also possible to use static or pre-shared keys in
+client implementations without sending this packet. Clients may
+naturally agree to use a key without sending any kind of indication
+to each other. The key may be for example a long-living static key
+that the clients has agreed to use at all times. Note that it is
+also possible to agree to use private message key by performing
+a Key Agreement. See the section 2.3.20 Key Agreement Payload.