-encrypting the envelope and salmon packet. This is then encrypted with the
-sender's private key and base64url encoded.
+encrypting the salmon packet. This is then encrypted with the sender's private
+key and base64url encoded.
+
+zot:env_key
+***********
+
+A suitable randomly generated encyption key of length 32 octets for encrypting
+the envelope. This is then encrypted with the recipient's public key and
+base64url encoded. For bulk deliveries, it is encrypted with the site bulk
+delivery public key.
+
+
+zot:env_iv
+**********
+
+A suitable randomly generated initialisation vector of length 16 octets for
+encrypting the envelope. This is then encrypted with the recipient's public
+key and base64url encoded. For bulk deliveries, it is encrypted with the site
+bulk delivery public key.
+