Implement NIP-04: Encrypted Direct Messages

lib/nostr/event_kind.rb

@@ -31,5 +31,13 @@ module Nostr
     # @return [Integer]
     #
     CONTACT_LIST = 3
+
+    # A special event with kind 4, meaning "encrypted direct message". An event of this kind has its +content+
+    # equal to the base64-encoded, aes-256-cbc encrypted string of anything a user wants to write, encrypted using a
+    # shared cipher generated by combining the recipient's public-key with the sender's private-key.
+    #
+    # @return [Integer]
+    #
+    ENCRYPTED_DIRECT_MESSAGE = 4
   end
 end