Good challenge! Here's a start: Say you and I want to chat with each other. We both pick a random key to store our messages in. Let's call those key[markchrist

Good challenge! Here's a start: Say you and I want to chat with each other. We both pick a random key to store our messages in. Let's call those key[markchristian] and key[heretoo]. Each of those has a read-only version -- readonly[markchristian] and readonly[heretoo]. I'll post the key readonly[markchristian] to "markchristian-to-heretoo". You post the key readonly[heretoo] to "heretoo-to-markchristian". Our chat clients can just poll those keys, looking for new messages -- whatever hand-wavy format we want to have. Problems: 1. Requires us to agree to chat ahead of time and know each other's usernames. 2. Nothing to stop a malicious third-party from putting a different readonly key at the "heretoo-to-markchristian" pointer keys.