How Glyphconnect protects you

What is protected

Message content. Every message is encrypted on your phone with a key that only you and the recipient can compute. The relay and anyone on the network only see random-looking bytes.
Who is talking to whom. The relay sees an anonymous mailbox address for the recipient. The sender's identity is inside the encrypted part, so the relay cannot tell who sent a message.
Message length. Messages are padded to size buckets, so short and long messages look alike.
Your keys. Generated on your phone and kept in the Keychain / Keystore. They never leave the device.
Your history. Stored in an encrypted file. Copying the file off the phone reveals nothing without the key in the Keychain / Keystore.
Contacts are verified by QR. You add people by scanning a code that contains their public keys and a signature, so nobody can add themselves as "your friend" or swap a key. You can also compare a safety number with a contact to detect interception.
Strangers cannot reach you directly. A first message from someone you have not added arrives as a request, and can only be plain text until you accept.

Key agreement: X25519. Signatures: Ed25519. Encryption: XChaCha20-Poly1305. Key derivation: HKDF-SHA-256.
Each message uses a fresh ephemeral key. The sender's identity key is sealed inside the first encryption layer, and the second layer mixes in the sender's static key, which proves who sent it.
All primitives come from the audited @noble libraries. Randomness comes from the operating system.
Groups are delivered pairwise: each member receives its own separately encrypted copy. There is no shared group key to leak or rotate, and a removed member simply stops receiving.

No double ratchet yet. If someone steals your phone and unlocks it, they can read stored history. If a recipient's long-term key were ever stolen, messages captured earlier could be decrypted by that key holder. Forward secrecy against recipient key compromise is planned.
Metadata. The relay can see recipient mailbox, timing, rough size and your IP address. Use a VPN or Tor-capable network if that matters to you.
Screenshots and screen recording. Turn on "Privacy screen" to block them on Android and hide the app in the app switcher.
A compromised phone (malware, someone who knows your passcode) defeats any messenger.
No backup. If you lose the phone, you lose your identity and history. That is deliberate.
Glyph languages are not encryption. A letter-for-symbol substitution can be broken by anyone who studies enough messages. It is a layer of privacy and fun on top of real encryption.
Sharing a language. Someone who accepts a language can read everything in it and could pass it on. Only share with people you trust.
Notifications. If you turn them on, the relay stores your phone's push token and asks Apple to show "You have a new message". The text of a message is never sent to Apple or shown on the lock screen. Apple and the relay can see that a notification was sent and when.

Please report security issues privately to piletskaya.i@empatixtech.com, or using "Contact support" in the app, rather than publicly.