count += len; // update number of bytes
        final int partLen = BLOCK_LENGTH - bufferNdx;
        int i = 0;
        if (len >= partLen) {
            System.arraycopy(input, offset, buffer, bufferNdx, partLen);

            transform(buffer, 0);

            for (i = partLen; i + BLOCK_LENGTH - 1 < len; i += BLOCK_LENGTH) {
                transform(input, offset + i);
            }

        <match value="Message-ID:" type="string" offset="0:8192"/>
      </match>
      <!-- match X- DKIM- ARC- at start of file and then require at least one
           of the usual: from, received, date...but look farther into the file
           because of the X|DKIM|ARC headers-->
      <match value="(X|DKIM|ARC)-" type="regex" offset="0">
        <match value="\nDate:" type="stringignorecase" offset="0:8192"/>