Enter the recipients by their code name. For example 1147. You can add multiple recipients. All users on Cyper.io are anonymous.
When creating a conversation, you can assign a secret code to unlock the conversation. The recipients will receive the code only once. If they forget the code, they can no longer access the conversation.
When the first 2 steps are done, you can send the message. The recipients can now answer your message and have a secret conversation.