Most messengers tell you they're secure. Few show their work.
Z-TEXT ran Microsoft's STRIDE threat model against its own architecture — the same framework security teams use internally, not a marketing checklist. Six categories: Spoofing, Tampering, Repudiation, Information Disclosure, Denial of Service, Elevation of Privilege.
Every answer got published. Including the one honest weak spot: a bypassed license costs Z-TEXT revenue, not user privacy.
A few highlights:
Spoofing — No phone number, no email. There's no identity to spoof in the first place, because none exists.
Tampering — Messages are shielded zk-SNARKs transactions on the BitcoinZ blockchain. Once confirmed, altering one means rewriting cryptographic math thousands of nodes already agreed on.
Denial of Service — The default messaging server isn't even Z-TEXT's own — it's community-run infrastructure (lightd.btcz.rocks), plus a self-hosted option and a Tor onion service. Nothing centralized to seize or pressure.
Elevation of Privilege — License enforcement is entirely client-side. A determined reverse engineer could unlock premium features on their own device. They can't unlock more privacy — message security was never behind that gate.
This follows the same pattern as Z-TEXT's public bug bounty and its LINDDUN privacy audit: publish the real answer, gaps included, before anyone has to ask.
Full breakdown: https://z-text.org/stride-threat-model-z-text-honest-results/
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