title: decrypt AES input on Flutter, when on web use cryptoJS AES
body: <p>On web, I'm using CryptoJS for decrypto JS:</p>
  
  <blockquote>
    <p>CryptoJS.AES.decrypt(inputBase64, key).toString(CryptoJS.enc.Utf8);</p>
  </blockquote>
  
  <p>Example:</p>
  
  <blockquote>
    <p>input: "tzfwnxVwE/qNoaWRRfqLp11ZyhB4UtKO+0/Lvv5B7eE="
    key: "20190225165436_15230006321670000_15510884759030000"</p>
  </blockquote>
  
  <p>On flutter I can't find any library to decrypt with a key of any length.</p>
  
  <p>I know "For AES, NIST selected three members of the Rijndael family, each with a block size of 128 bits, but three different key lengths: 128, 192 and 256 bits.
  "</p>
  
  <p>But I don't know how to convert any length key to 128 bit format?</p>