1# 🧪 fluorine.js - NIP-44 encryption23fluorine.js is a miniature nostr-tools nip44: NIP-44 v2 encryption in about 3.5kb of ChaCha20, HMAC-SHA256 and padding over `crypto.subtle`. It derives conversation keys through helium.js's ECDH, then encrypts and decrypts payloads that any NIP-44 client can read. Loaded after helium.js, it gives helium's local signer a `nip44` face like a NIP-07 extension's, and chlorine.js and iodine.js use it for private messages and encrypted content.45```html6<script src="helium.js"></script>7<script src="fluorine.js"></script>8<script type="module">9 let box = await helium.signer.nip44.encrypt(theirPubkey, "meet at noon")10 let text = await helium.signer.nip44.decrypt(theirPubkey, box)11</script>12```1314The local key encrypts a message only it and the owner of `theirPubkey` can read, and decrypts it again.1516## API1718| function | returns |19|---|---|20| `fluorine.key(sk, pk)` | conversation key (`Uint8Array(32)`) for a hex secret key and hex public key |21| `fluorine.encrypt(text, key, nonce?)` | base64 payload. `nonce` is a `Uint8Array(32)`, random by default |22| `fluorine.decrypt(payload, key)` | plaintext, or throws on a bad version, length, MAC or padding |23| `fluorine.nip44(sk)` | NIP-07 shaped `{encrypt(pk, text), decrypt(pk, payload)}` for that key, caching conversation keys |24| `fluorine.pad(n)` | padded length for an `n` byte message |25| `helium.signer.nip44` | `{encrypt, decrypt}` using `helium.key()`, added when helium.js is loaded first |2627All functions return promises except `nip44` and `pad`. Plaintext must be 1 to 65535 bytes of UTF-8.2829## Caveats3031ECDH runs on helium's BigInt arithmetic, which is not constant time, and the local key lives in `localStorage`. Prefer an extension's `nostr.nip44` for keys that matter. Tests check every official NIP-44 vector and round trips against nostr-tools.