Function boxEncrypt

boxEncrypt(
    message: Uint8Array,
    recipientPublicKey: Uint8Array,
    senderSecretKey: Uint8Array,
): Uint8Array
NaCl box encrypt: authenticated encryption where both sender and recipient are known.

Uses X25519 for key agreement and XSalsa20-Poly1305 for encryption. Output format: nonce(24) || ciphertext (ciphertext includes 16-byte auth tag).
Parameters
- message: Uint8Array
  The plaintext bytes to encrypt.
- recipientPublicKey: Uint8Array
  The recipient's 32-byte Curve25519 public key.
- senderSecretKey: Uint8Array
  The sender's 32-byte Curve25519 secret key.
Returns Uint8Array
A single Uint8Array with nonce prepended to ciphertext.
Throws
If encryption fails.
Example
```
import { boxEncrypt, boxDecrypt } from "@polkadot-apps/crypto";
import nacl from "tweetnacl";

const alice = nacl.box.keyPair();
const bob = nacl.box.keyPair();

const packed = boxEncrypt(message, bob.publicKey, alice.secretKey);
const plaintext = boxDecrypt(packed, alice.publicKey, bob.secretKey);
```
- Defined in packages/crypto/src/nacl.ts:106