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

Quick start guide

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

1
Load, then go offline
Open this file in your browser, wait for the runtime status above to read “ready”, then disable Wi‑Fi or unplug Ethernet.
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.

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

initialising…

Loading library versions…

Tip: once the status flips to ready, disconnect from the network before entering any secrets.

No telemetry, no calls home. Paste your encrypted key and password below to extract the 32-byte secret and its bech32 nsec.

Take your device offline to decrypt your ncryptsec.

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.

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.
When finished, hit Clear to wipe inputs from memory.

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.