// smaller)
	lastPartSize, _ := sio.EncryptedSize(uint64(sizes[partEnd]))
	if endEncOffset > encCumulativeSum+int64(lastPartSize) {
		endEncOffset = encCumulativeSum + int64(lastPartSize)
	}
	encLength = endEncOffset - encOff
	// Set the sequence number as the starting package number of
	// the requested block
	seqNumber = uint32(startPkgNum)
	return encOff, encLength, skipLen, seqNumber, partStart, nil
}