Offline-only toolkit

NIP-49 Offline Decryptor

Bring your ncryptsec, pull the plug, and recover the private key entirely inside this single, auditable HTML file.

🔌 Works without a network connection 🧮 Built-in libsodium + scrypt helpers 📄 Export a self-contained copy

Runtime status

Everything required for password stretching, AEAD decryption, and bech32 conversion ships directly with this page.

initialising…

Loading library versions…

Decrypt your ncryptsec

No telemetry, no calls home, no external dependencies. Take your device offline, paste your encrypted key and password to extract the 32-byte secret HEX and its bech32 nsec.

YOUR DEVICE IS CONNECTED TO THE INTERNET. This window will activate once no internet connection is detected.

Quick start guide

Follow these steps each time you unlock your nsec from a NIP-49 secret.

1
Download, then go offline
Save this HTML file and open the page in your browswer, then disable Wi‑Fi and/or unplug Ethernet, the "Decrypt your ncryptsec" window will activate.
2
Paste your protected key
Enter the full ncryptsec string and your password. The app derives the scrypt key and attempts XChaCha20-Poly1305 decryption locally.
3
Record the results securely
Copy the 32-byte hex key or the regenerated nsec. Re-enable your connection only after you have safely stored the output.

What’s inside this page?

A curated bundle of battle-tested libraries, baked directly into the source so you can inspect every byte.

libsodiumProvides crypto_aead_xchacha20poly1305_ietf_decrypt for authenticated decryption.
Scrypt derivation helpersStretch passwords into 256-bit keys using the NIP-49 parameters.
bech32 / bech32m toolsDecode ncryptsec payloads and emit friendly nsec outputs.

Safety checklist

Keep your keys safe with these quick reminders.

Always verify you trust the source of this HTML file. Review it or host it yourself.
Stay offline while working with secrets. Reconnect only after clearing the inputs.
Use a unique, high-entropy password for each encrypted key.

Don't Trust - Verify

You don't need to trust anyone to run this code.

You can save the contents of this HTML file (File - Save As/Save Page As)
Read every line of code and look for yourse.f
Export buttonGenerates a downloadable, self-contained HTML copy for air-gapped machines.