Cipher is experimental and has not been independently audited. It has been run only on an Android emulator, never on a physical device, and its privacy route has not been validated against the live Tor network. Do not rely on it to protect anyone who could be harmed by a failure. See the security status and SECURITY_TODO for known open issues.

Please do not report exploitable vulnerabilities in public issues, pull requests or discussions.

Use GitHub's private vulnerability reporting: open the repository's Security tab and choose Report a vulnerability. Include what you found, how to reproduce it, the affected component and version/commit, and what an attacker gains. If you can, include a failing test.

If private reporting is unavailable for any reason, open a public issue that says only that you have a security report and ask for a private channel — without any technical detail.

This is a small project. We will try to acknowledge reports and keep you informed, but we do not promise a response time, a fix time or a bounty.

In scope:

• the Rust crates (cipher-core, cipher-wire, cipher-relay, cipher-ffi) and the Android app in this repository;
• the cryptographic compositions listed in EXTERNAL_REVIEW_SCOPE (history keys, vault, request signing, delivery capabilities);
• failures of a documented security invariant (SECURITY_INVARIANTS) or of a claim in the threat models;
• the privacy transport's fail-closed behaviour (any path that sends data to the relay without the configured route in a release build);
• secrets or personal data accidentally committed to this repository.

Out of scope:

• vulnerabilities in upstream dependencies that are not reachable through Cipher (report those upstream; tell us if Cipher is affected);
• a compromised, unlocked, rooted or malware-infected device, and attacks that require physical coercion;
• anonymity or global-observer / end-to-end timing-correlation attacks (Cipher states it does not defend against them);
• the throwaway test CA, the devonly-not-a-secret test database password and the development SOCKS5 test double (public, test-only, documented);
• denial of service by volume against a self-hosted relay without a demonstrated amplification flaw;
• reports without a security impact (missing headers on non-sensitive responses, theoretical issues with no scenario).

Please give us a reasonable chance to fix a problem before disclosing it. We will credit you in the fix if you wish.