Encdec.enc_uint32le(0x00000101, blob, 0); // Header
        Encdec.enc_uint32le(0x00000000, blob, 4); // Reserved
        Encdec.enc_uint64le(nanos1601, blob, 8);
        System.arraycopy(clientChallenge, 0, blob, 16, 8);
        Encdec.enc_uint32le(0x00000000, blob, 24); // Unknown
        System.arraycopy(avPairs, 0, blob, 28, avPairsLength);
        Encdec.enc_uint32le(0x00000000, blob, 28 + avPairsLength);

        final byte[] temp = new byte[28 + avPairsLength + 4];

        Encdec.enc_uint32le(0x00000101, temp, 0); // Header
        Encdec.enc_uint32le(0x00000000, temp, 4); // Reserved
        Encdec.enc_uint64le(nanos1601, temp, 8);
        System.arraycopy(clientChallenge, 0, temp, 16, 8);
        Encdec.enc_uint32le(0x00000000, temp, 24); // Unknown
        if (avPairs != null) {

        if (setmid) {
            makeKey(req);
        } else {
            req.setMid(0);
            this.mid.set(1);
        }
        final int n = req.encode(this.sbuf, 4);
        Encdec.enc_uint32be(n & 0xFFFF, this.sbuf, 0); /* 4 byte ssn msg header */

        if (log.isTraceEnabled()) {
            log.trace(req.toString());
            log.trace(Hexdump.toHexString(this.sbuf, 4, n));
        }