node.js - crypto decipher returning unknown characters when deciphering from base64 to utf-8

Question

I'm building a encryption/decryption module for environment variables that has two functions

1. encrypt the contents of .env & writes it to encrypted.env
2. decrypt the contents of encrypted.env & write it to .env

I've run into an issue where the first line of .env is unknown characters after decryption.

original contents of .env

STAGE="DEVELOPMENT"
USERNAME="Greggo"
PASSWORD="myPassw0rd?1234"

encrypted.env:

PEGeGD40pJoLBN2cQvFgPm/KrWxMakRkKkhbUlzQdsNF8zrmr0w5dUsEVINRfXPPM23W8No8HF5uCzqRCMG98g5MHDZkHpXE1s4/cevGTv0=

decrypted .env:

?~#?A??YHQ??//NT"
USERNAME="Greggo"
PASSWORD="myPassw0rd?1234"

encrypt.js

fs.readFile('./.env', 'utf-8', (err, data) => {
  if (err) {
    throw err;
  }
  console.log(data);
  crypto.scrypt('glfgmkjldpg90d9gd88k3kfs;fsdl;f99sfFKkdl;dlda', 'salt', 24, (err, key) => {
    if (err) {
      throw err;
    }
    crypto.randomFill(new Uint8Array(16), (err, iv) => {
      if (err) {
        throw err;
      }
      const cipher = crypto.createCipheriv('aes-192-cbc', key, iv);

      let encrypted = cipher.update(data, 'utf-8', 'base64');
      encrypted += cipher.final('base64');
      console.log(encrypted);

      fs.writeFile('./encrypted.env', encrypted, (err, data) => {
        if (err) {
          throw err;
        }
        console.log(data);
      });
    });
  })
});

decrypt.js

fs.readFile('./encrypted.env', 'utf-8', (err, encryptedData) => {
  if (err) {
    throw err;
  }
  console.log(encryptedData);
  const key = crypto.scryptSync('glfgmkjldpg90d9gd88k3kfs;fsdl;f99sfFKkdl;dlda', 'salt', SALT_ROUNDS);
  const iv = Buffer.alloc(16, 0);

  const decipher = crypto.createDecipheriv('aes-192-cbc', key, iv);

  let decrypted = decipher.update(encryptedData, 'base64', 'utf-8');
  decrypted += decipher.final('utf-8');
  console.log(decrypted);

  fs.writeFile('./.env', decrypted, (err, decryptedData) => {
    if (err) {
      throw err;
    }
    console.log(decryptedData);
  });
});

question from:https://stackoverflow.com/questions/65944612/crypto-decipher-returning-unknown-characters-when-deciphering-from-base64-to-utf

Answer 1

Your encryptor has a random IV, generated by randomFill, but you then seem to throw it away. Your decryption code creates an IV filled with zeros. Your IVs need to be the same. Typically you'd do that by prepending the randomly generated IV to the ciphertext in the encryptor, and reading it off in the decryptor. But in any case they have to be the same.