Decrypting data with MetaMas

Decryption function.ts

const ascii85 = require('ascii85');

async function decryptData(account: string, data: Buffer): Promise<Buffer> {
  // Reconstructing the original object outputed by encryption
  const structuredData = {
    version: 'x25519-xsalsa20-poly1305',
    ephemPublicKey: data.slice(0, 32).toString('base64'),
    nonce: data.slice(32, 56).toString('base64'),
    ciphertext: data.slice(56).toString('base64'),
  };
  // Convert data to hex string required by MetaMask
  const ct = `0x${Buffer.from(JSON.stringify(structuredData), 'utf8').toString('hex')}`;
  // Send request to MetaMask to decrypt the ciphertext
  // Once again application must have acces to the account
  const decrypt = await window.ethereum.request({
    method: 'eth_decrypt',
    params: [ct, account],
  });
  // Decode the base85 to final bytes
  return ascii85.decode(decrypt);
}