Cellular Network Infrastructure » IMSI Pseudonymization

	/*

	This was used to find out that the first byte of a text field seems to be 4.

	private byte[] getResponseDBG()

	{

		ProactiveResponseHandler rspHdlr;

		byte resp[];

		byte strlen = -1;

		rspHdlr = ProactiveResponseHandler.getTheHandler();

		for (byte occurence = 1; occurence <= 3; occurence++) {

			short len;

			try {

				if (rspHdlr.findTLV(TAG_TEXT_STRING, (byte)occurence) != TLV_NOT_FOUND) {

					if ((len = rspHdlr.getValueLength()) > 1) {

						len = 3;

						resp = new byte[len];

						rspHdlr.copyValue((short)0, resp, (short)0, (short)(len));

						showMsg(resp);

						showMsgAndWaitKey(Bytes.hexdump(resp));

						return resp;

					}

				}

			} catch (Exception e) {

				showError((short)(30 + occurence));

				return null;

			}

		}

		showError((short)(39));

		return null;

	}

	*/

	private byte[] prompt(byte[] msg, byte[] prefillVal, short minLen, short maxLen) {

		if (prefillVal != null && prefillVal.length > 0) {

			/* appendTLV() expects the first byte to be some header before the actual text.

			 * At first I thought it was the value's length, but turned out to only work for lengths under 8...

			 * In the end I reversed the value 4 from the first byte read by rspHdlr.copyValue() for

			 * TAG_TEXT_STRING fields. As long as we write 4 into the first byte, things just work out,

			 * apparently.

			 * Fucking well could have said so in the API docs, too; oh the brain damage, oh the hours wasted.

			 * This is the appendTLV() variant that writes one byte ahead of writing an array: */

			proHdlr.appendTLV((byte)(TAG_DEFAULT_TEXT), (byte)4, prefillVal, (short)0,

					  (short)(prefillVal.length));

		}