Alice and Bob use the Signal protocol to derive a key chain, sequentially using keys to encrypt/decrypt messages, and delete each key after use. Alice Bob k1 k1 k2 k2 k3 k3 k4 k4 k5 k5 k6 k6 k7 k7 k8 k8 k9 k9 k10 k10 k11 k11 ……. …… View quoted note →

The "ecash sat postage stamp" is underrated; it should receive as much attention as Zap, if not more. View quoted note →

The "ecash sat postage stamp" will become a unique and powerful weapon for Nostr app developers. View quoted note →

Nostr app developers, please do not fear the "ecash sat postage stamp"—be brave. View quoted note →

Ecash sat is a universal access token for relay servers. “Initially, we thought of having relays issue one-time anonymous access tokens that users could purchase and use for anonymous pay-per-use. Later, we realized that using Bitcoin ecash as postage for messages would be a better solution.” View quoted note →

Later, we will write a note explaining the two ways to add friends in Keychat: through QR codes and through Npub, which involves the Signal protocol. View quoted note →

Keychat's new version for Android APK download :

GitHub

Releases · keychat-io/keychat-app

Keychat is the super app for Bitcoiners. Autonomous IDs, Bitcoin ecash wallet, secure chat, and rich mini apps — all in Keychat. Autonomy. Securi...

The new version introduces a medium group feature, replacing the previous shared key group. It also includes nsec login, allowing for the simultaneous use of existing nsec and seed phrases. (Keychat is currently not stable enough, so early testers can only download it through the Android APK. We are working on making it stable, and then we will add it to the iOS and Android app stores.) View quoted note →

Why does Keychat need stamps (ecash sats as message stamps)? View quoted note →

Let's explore the concept of a medium group from an interesting perspective. Suppose a medium group consists of three regular members, A, B, and C, along with one special member, D. Why is D special? Because the identity of D is shared among A, B, and C. When A sends a group message, it is effectively sending a message to D, allowing us to reuse Keychat's one-on-one chat functionality. Members B and C use D's identity to receive and decrypt the message sent by A. However, D does not respond to messages, meaning that the messaging in the Medium group utilizes only one of the ratchets in the double ratchet algorithm (the symmetric ratchet), and not the DH ratchet. Therefore, messages in the Medium group have forward secrecy similar to one-on-one messages but lack backward secrecy. How can we achieve some degree of backward secrecy? By changing D, for instance to E, which effectively resets the DH ratchet. When the Medium group adds or removes members, the special member is updated, thereby gaining some degree of backward secrecy. If there's a need for more efficient and frequent changes of the special member, then we turn to the MLS protocol. View quoted note →

Using continually updated sender addresses instead of sender IDs better protects metadata privacy. This privacy mechanism requires a stamp to function effectively, as stamps address the issue of spam. View quoted note →

Apps that assume users are foolish can move quickly. Apps that assume users are smart can go far.

We are very grateful to those who repost our notes; it is the most crucial way for our ideas to reach more people. We write explanatory notes to help more people understand what makes a good chat app and can verify Keychat's design for themselves. View quoted note →