title: AES_128_GCM: Decrypting IV in Lua
body: <p>I have to decrypt a message encrypted by an other party in Java using AES-128-GCM.</p>
  
  <p>They gave me the code they are using for encrypt/decrypt functions, but I, having almost no background in cryptography, don't understand this line:</p>
  
  <pre><code>javax.crypto.spec.GCMParameterSpec iv = new javax.crypto.spec.GCMParameterSpec(128, ivbyte);
  </code></pre>
  
  <p>It is used both in encrypt and decrypt.</p>
  
  <p>What does it do? How can I translate this to Lua on our side?</p>