Now that we have all the security flow, let's make the application actually secure, using <abbr title="JSON Web Tokens">JWT</abbr> tokens and secure password hashing.

This code is something you can actually use in your application, save the password hashes in your database, etc.

We are going to start from where we left in the previous chapter and increment it.

## About JWT { #about-jwt }

JWT means "JSON Web Tokens".

    var finished: Boolean = false,
  ) : Sink {
    /**
     * Buffer of outgoing data. This batches writes of small writes into this sink as larges frames
     * written to the outgoing connection. Batching saves the (small) framing overhead.
     */
    private val sendBuffer = Buffer()

    /** Trailers to send at the end of the stream. */
    var trailers: Headers? = null

    var closed: Boolean = false

		err = p.parseJSON(data)
		if err != nil {
			return err
		}

		if p.Version == 0 {
			// This means that policy was in the old version (without any
			// timestamp info). We fetch the mod time of the file and save
			// that as create and update date.
			p.CreateDate = objInfo.ModTime
			p.UpdateDate = objInfo.ModTime
		}

		m[policy] = p
		return nil
	}
}

   * Hashing} class is loaded. <b>Do not use this method</b> if hash codes may escape the current
   * process in any way, for example being sent over RPC, or saved to disk. For a general-purpose,
   * non-cryptographic hash function that will never change behavior, we suggest {@link
   * #murmur3_128}.
   *

  }

  /**
   * Marks the given node as 'deleted' (null waiter) and then scans the list to unlink all deleted
   * nodes. This is an O(n) operation in the common case (and O(n^2) in the worst), but we are saved
   * by two things.
   *
   * <ul>
   *   <li>This is only called when a waiting thread times out or is interrupted. Both of which
   *       should be rare.
   *   <li>The waiters list should be very short.

    init(expectedSize);
  }

  /** Pseudoconstructor for serialization support. */
  void init(int expectedSize) {
    Preconditions.checkArgument(expectedSize >= 0, "Expected size must be >= 0");

    // Save expectedSize for use in allocArrays()
    this.metadata = Ints.constrainToRange(expectedSize, 1, CompactHashing.MAX_SIZE);
  }

  /** Returns whether arrays need to be allocated. */
  boolean needsAllocArrays() {

  // it doesn't escape this class
  @SuppressWarnings("Immutable")
  private final long[] array;

  /*
   * TODO(kevinb): evaluate the trade-offs of going bimorphic to save these two fields from most
   * instances. Note that the instances that would get smaller are the right set to care about
   * optimizing, because the rest have the option of calling `trimmed`.
   */

   * collection-based APIs. Further, this method allows precise control over the runtime type of the
   * output array, and may, under certain circumstances, be used to save allocation costs.
   *
   * <p>Suppose {@code x} is a queue known to contain only strings. The following code can be used
   * to dump the queue into a newly allocated array of {@code String}:
   *
   * <pre>

  // it doesn't escape this class
  @SuppressWarnings("Immutable")
  private final int[] array;

  /*
   * TODO(kevinb): evaluate the trade-offs of going bimorphic to save these two fields from most
   * instances. Note that the instances that would get smaller are the right set to care about
   * optimizing, because the rest have the option of calling `trimmed`.
   */

            if (LogStream.level > 1) {
                log.println("SecurityException: jcifs.smb1 will ignore System properties");
            }
        }
    }

    /**
     * Save the configuration properties to an output stream.
     *
     * @param out the output stream to write properties to
     * @param header a descriptive header for the properties
     * @throws IOException if an I/O error occurs