Encrypting and decrypting a message using secret key aead xchacha20poly1305_ietf (libsodium js)

libsodium xchacha20poly1305_ietf.js

'use strict'

const sodium = require('libsodium-wrappers');
sodium.ready.then(function()
{
    console.log('sodium ready');

    //xchacha20ploy1305 ietf
    //A key and a nonce are generated by the encrypting party. The decrypting
    //party should use them for decryption
    
    //encryption
    let key3 = sodium.crypto_aead_xchacha20poly1305_ietf_keygen();
    let nonce3 = sodium.randombytes_buf(sodium.crypto_secretbox_NONCEBYTES);
    let ciphertext3 = sodium.crypto_aead_xchacha20poly1305_ietf_encrypt(
        'secret message.',
        null,
        null,
        nonce3,
        key3
    )
    console.log('ciphertext')
    console.log(ciphertext3)

    //decryption.
    let decryptedText3 = sodium.crypto_aead_xchacha20poly1305_ietf_decrypt(
        null,
        ciphertext3,
        null,
        nonce3,
        key3
    )
    console.log('decrypted ciphertext')
    console.log(sodium.to_string(decryptedText3))
  
})