AES CBC 256 using Node.js [crypto]

cbc256

/*
  p is plaintext (non-encrypted value) OR CIPHER (already encrypted text)
  t is either false [cbc256("value", false, "key")] for encryption or true for decryption
  k is key.
*/

/*
  Example:
    val = "value";
    v = cbc256(val, false, "key"); 
    v_ = cbc256(v, true, "key")
      // val == v_
*/

cbc256 = function (p, t, k) {
        t = t || 0;
        crypto = this["crypto"] || require("crypto");

        z = "";

        if (!t) {
                _c = crypto.createCipher("aes-256-cbc", k);
                return _c.update(p, "utf8", "hex"), _c["final"]("hex");
        } else {
                _c = crypto.createDecipher("aes-256-cbc", k);
                return _c.update(p, "hex", "utf8"), _c["final"]("utf8");
        }
}