QNSQY for Claude

QNSQY is a post-quantum cryptography (PQC) toolkit from Quantum Sequrity. This plugin lets Claude Code use the QNSQY program installed on your own computer. With it, Claude can:

• find quantum-vulnerable cryptography and write a CBOM (cryptography bill of materials);
• encrypt files for a recipient's public key with ML-KEM;
• export your public key;
• check ML-DSA signatures, QNSQY release signatures, hashes and encrypted files.

The plugin's tools have no field for a password, passphrase, private key, API key or payment token, refuse any call that adds one, and never return one.

Requirements

• Linux (x86_64 or ARM64) with QNSQY's current release installed from our signed packages at https://quantumsequrity.com/download, so that qnsqy is on your PATH. The plugin starts whatever qnsqy your PATH finds first, so install QNSQY only from there. Windows and macOS are not supported by the plugin yet.
• Claude Code on the same computer. In claude.ai chat the plugin has no QNSQY tools, because chat cannot start programs on your computer. Cowork has not been tested.
• A QNSQY account. Sign in with the QNSQY app, or with qnsqy login in your own terminal outside Claude.

Install

In your shell:

claude plugin marketplace add quantumsequrity/qnsqy-claude-plugin
claude plugin install qnsqy@quantumsequrity

Then start a new Claude Code session, or run /reload-plugins.

Using Codex? Install our Codex plugin instead: https://github.com/quantumsequrity/qnsqy-codex

If you added QNSQY to Claude Code yourself before, remove that entry with claude mcp remove <its name>, so that Claude sees only this plugin's tools. It is an MCP server that runs qnsqy --mcp, and claude mcp list shows its name.

What the plugin runs, sends and fetches

• Runs: Claude Code starts your installed QNSQY as a local tool server with qnsqy --mcp-profile=strict. Each tool call runs the matching QNSQY command on your computer, inside QNSQY's sandbox.

• Tools: Claude sees 13 tools (10 on the Free plan):

  • scan;
  • encrypt and batch encrypt;
  • export a public key;
  • verify, batch verify and verify a release;
  • hash, check a hash, and check an encrypted file;
  • status, usage and version.

  Batch encrypt, batch verify and key export need the Pro plan or above.

• Sends: the plugin itself sends nothing. QNSQY talks to our billing server, billing.quantumsequrity.com, to check your plan and record usage, as section 2 of our privacy policy describes:

  • At sign-in and at each check-in: a device ID derived on your device, your computer's name and the operating system type.
  • Before a metered operation: the operation type, the data size, the program version and the chosen algorithms.
  • After a metered operation: whether it succeeded, the bytes processed and how long it took.
  • For every operation: a usage receipt with the operation type, data size, time, result, credits used and a hash of the file's path. The path itself is not sent, but a path that is easy to guess can be checked against its hash.
  • Audit forwarding: if you have set up audit log forwarding in QNSQY's settings, audit events also go to the syslog server you configured.

  QNSQY never sends your files, their contents, your passwords or your keys.

• Environment: QNSQY's commands receive only these QNSQY variables:

  • QNSQY_API_KEY, QNSQY_CONFIG_DIR, QNSQY_LOG_LEVEL, QNSQY_REQUIRE_INTEGRITY and QNSQY_LICENSE_DATA, if you have set them;
  • QNSQY_MACHINE_KEY, which QNSQY sets itself for its own commands.

  In this plugin they never receive a payment token or remote-storage keys.

• Claude sees what you ask and what the tools return: file names, paths and results. All of this is part of your conversation with Claude, which is why the tools never take secrets.

• Fetches: nothing. The plugin downloads no code.

Passwords, passphrases and keys

• No secret fields. The tools have no field for a password, passphrase, private key, API key or payment token. QNSQY refuses any call that adds one before doing anything.
• Encryption. Encryption in the plugin is to a public key file.
• Steps that need a password. To decrypt, sign, create keys or sign in, use the QNSQY app (from your desktop menu, or type ! qnsqy --gui in Claude Code), or run qnsqy in your own terminal. QNSQY asks for the password in its own window or prompt. Create your account at https://quantumsequrity.com or in the app, and manage API keys in your dashboard.

Limits

• Tool calls can be steered. Text that Claude reads, for example inside a scanned file or a web page, can try to steer it. The strict tools refuse unlisted fields, including every secret field, and cannot overwrite or delete files. A valid call is still possible, such as encrypting a file to the wrong public key. Check each QNSQY call before you approve it. Whether Claude Code asks you first depends on your permission settings.
• Claude's own shell is outside the plugin. Claude Code can also run qnsqy in its shell. A password on such a command line, for example one piped into --password-stdin, reaches the chat. Never approve a qnsqy command that carries a password.
• Typed secrets. If you type a password into the chat itself, it is part of the conversation, so don't.

Example prompts

1. "Scan ~/projects/billing for quantum-vulnerable cryptography and write a CycloneDX CBOM to cbom.json."
2. "Encrypt report.pdf for the public key in alice-enc.pub."
3. "Export my public key named work to work.pub so that I can send it to a colleague."
4. "Check the signature on contract.qs with bob-sign.pub, then hash invoice.pdf with BLAKE3."
5. "Which QNSQY plan am I on, and how much have I used?"

Troubleshooting

• No QNSQY tools appear, or the server failed to start. One of these is the cause:

  • QNSQY is not installed;
  • qnsqy is not on your PATH;
  • your QNSQY is older than the current release. Older releases do not know the plugin's option, so they stop.

  Install the current release from https://quantumsequrity.com/download, then run /reload-plugins. On Windows and macOS the plugin is not available yet.

• "Not logged in" or "Login required": sign in with the QNSQY app, or with qnsqy login in your own terminal. Scanning needs a signed-in account, on every plan.

• A plan limit message: some algorithms, and the batch and key-export tools, need the Pro or Business plan (https://quantumsequrity.com/pricing).

• "Not accepted in the strict profile": the plugin never accepts passwords or keys. Finish that step in the QNSQY app or in your own terminal.

• The QNSQY app does not open on a desktop that has only X11: the app needs Wayland. It opens on X11 only with --allow-x11, which we do not recommend, because X11 lets other programs read keystrokes. Use the matching qnsqy command in your own terminal instead, for example qnsqy decrypt.

Security and support

• Certifications: QNSQY implements the FIPS 203 (ML-KEM) and FIPS 204 (ML-DSA) algorithms. It is not FIPS 140-validated, SOC 2 certified, FedRAMP authorized or HIPAA-audited.
• Support: support@quantumsequrity.com
• Security reports: security@quantumsequrity.com (https://quantumsequrity.com/security)
• Privacy policy: https://quantumsequrity.com/privacy
• Terms: https://quantumsequrity.com/terms

Licence

See LICENSE.