How to create a KEY and IV for Crypto

Question

Hi, I’m trying to make an AES-256-cbc encryption, and I’m having trouble creating a Key and an IV... I tried to use

crypto.randomBytes(32)
crypto.randomBytes(16)

32 to key, and 16 to IV. That way encrypt_token works smoothly, but decrypt_token error:

internal/crypto/cipher.js:174
  const ret = this[kHandle].final();
                            ^

Error: error:06065064:digital envelope routines:EVP_DecryptFinal_ex:bad decrypt
    at Decipheriv.final (internal/crypto/cipher.js:174:29)
    at decrypt_token (/home/joao/test.js:95:16)
    at Object.<anonymous> (/home/joao/test.js:101:29)
    at Module._compile (internal/modules/cjs/loader.js:1118:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1138:10)
    at Module.load (internal/modules/cjs/loader.js:982:32)
    at Function.Module._load (internal/modules/cjs/loader.js:875:14)
    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:71:12)
    at internal/main/run_main_module.js:17:47 {
  library: 'digital envelope routines',
  function: 'EVP_DecryptFinal_ex',
  reason: 'bad decrypt',
  code: 'ERR_OSSL_EVP_BAD_DECRYPT'
}

Follows the code:

var crypto = require('crypto'),
  key = 'AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA',
  iv = 'AAAAAAAAAAAAAAAA';

function encrypt_token(data) {
  var encipher = crypto.createCipheriv('aes-256-cbc', key, iv),
    buffer = Buffer.concat([
      encipher.update(data),
      encipher.final()
    ]);
  return buffer.toString('base64');
}

function decrypt_token(data) {
  var decipher = crypto.createDecipheriv('aes-256-cbc', key, iv),
    buffer = Buffer.concat([
      decipher.update(Buffer.from(data, 'base64')),
      decipher.final()
    ]);
  return buffer.toString();
}

console.log('encriptado: ', encrypt_token('dmyz.org'));
console.log('decriptado: ', decrypt_token('FSfhJ/gk3iEJOPVLyFVc2Q=='));

Att.