Monthly Archives: June 2015

How to overcome “A required drive partition is missing” in Windows 8.1 reset

Here is the scenario: an HP all-in-one PC gets a virus and as a precaution the owner wishes to reinstall Windows.

The recovery drive on the PC is intact, but attempting to use the Windows 8.1 troubleshooting tools to “Reset your PC” (in effect reinstalling Windows) raises the error “A required drive partition is missing”.

This seems to be a common scenario in cases where the PC was supplied with Windows 8 and upgraded to Windows 8.1. The problem seems to be that Windows 8.1 makes some changes to the drive partitions that make it incompatible with the Windows 8.0 recovery partition.

Here is the workaround I used:

1. In Windows 8.1, make a recovery drive. To do this, first connect a USB drive that you are happy to have wiped. It will need a capacity of around 16GB or more. Then run Control Panel, search for “recovery”, and choose Create a recovery drive.


2. When creating the recovery drive, make sure the option to include the recovery partition is checked. This will copy the recovery partition from the PC to the USB drive.

3. When you are done, you will be able to boot from the USB drive. You could choose the Reset option from there, however you will still get the error. First, go to Troubleshooting and Advanced and select the command prompt. When the command prompt opens, type:


Now type:

list disk

You will see two disks (or more) listed, one for the USB boot device, and the others the disk(s) in the PC. Select the internal boot drive. It is normally obvious from the sizes which is which. Select it by typing:

select disk n

where n is the number of the drive as shown by list disk.

WARNING: the next step will delete all data on the selected drive. If in doubt, back out and make a backup of the drive before proceeding. If something goes wrong, your PC will no longer be bootable and you will need recovery media from the manufacturer, or to buy a new copy of Windows.

Once you are happy that it is safe to delete everything from the drive, type:



clean all

The first command does a quick removal of the partition table from the drive but does not zero the data; it will be invisible but possibly recoverable using data recovery tools. The second command zeroes all the data and takes much longer (several hours), but it is more secure, if for example you want to sell or transfer the PC.

Once this is done,reboot the PC using the USB recovery drive. Select troubleshooting, then Reset your PC. This time it will work and you will be back in Windows 8.0.

Note: This scenario is common enough that it seems to be a flaw in the Windows 8.x recovery tools. I do not understand why Microsoft has so little regard for its users attempting to recover Windows (and usually highly stressed) that it has not fixed this problem.

Note 2: What if you cannot boot into Windows 8.1 to make the recovery drive? I have not tried it, but in theory it should be possible to create a recovery drive on another PC and copy the recovery drive to it.

DatAshur encrypted drives: protect your data but be sure to back it up too

The iStorage DataAshur USB flash drive is a neat way to encrypt your data. Lost USB storage devices are a common cause of data theft anxiety: in most cases the finder won’t care about your data but you can never be certain.


The DatAshur is simple to operate but highly secure, presuming it meets the advertised specification. All data written to the drive is automatically encrypted with 256-bit AES CBC (Advanced Encryption Standard with Cipher Block Chaining) and meets the US FIPS 140-2 standard. The encryption is transparent to the operating system, since decryption is built into the device and enabled by entering a PIN of 7 to 15 digits.

Note that a snag with this arrangement is that if your PC is compromised a hacker might be able to read the data while the drive is connected. If you are really anxious you could get round this by working offline, or perhaps using Microsoft’s clever Windows to Go (WTG) technology where you boot from a USB device and work in isolation from the host operating system. Unfortunately DatAshur does not support WTG (as far as I know) but there are alternatives which do, or you could boot into WTG and then insert your DatAshur device.

Normally you enter the PIN to unlock the drive before connecting it to a PC or Mac. This does mean that the DatAshur requires a battery, and a rechargeable battery is built in. However if the battery is exhausted you can still get your data back by recharging the device (it charges whenever it is plugged into a USB port).

OK, so what happens if a bad guy gets your device and enters PINs repeatedly until the right one is found? This will not work (unless you chose 1234567 or something like that) since after 10 failed tries the device resets, deleting all your data.

You should avoid, then, the following scenario. You give your DatAshur drive to your friend to show it off. “I’ve just updated all my expenses on this and there is no way you’ll be able to get at the data”. Friend fiddles for a bit. “Indeed,and neither can you”.

Here then is the security dilemma: the better the security, the more you risk losing access to your own data.

The DatAshur does have an additional feature which mitigates the risk of forgetting the PIN. You can actually set two PINs, a user PIN and an admin PIN. The admin PIN could be retained by a security department at work, or kept in some other safe place. This still will not rescue you though if more than 10 attempts are made.

What this means is that data you cannot afford to lose must be backed up as well as encrypted, with all the complexity that backup involves (must be off-site and secure).

Still, if you understand the implications this is a neat solution, provided you do not need to use those pesky mobile devices that lack USB ports.

The product tested has a capacity from 4GB to 32GB and has a smart, strong metal case. The plastic personal edition runs from 8GB to 32GB and is less robust. An SSD model offers from 30GB to 240GB, and larger desktop units support SSD or hard drive storage from 64GB to 6TB, with USB 3.0 for fast data transfer.

Prices range from around £30 inc VAT for an 8GB Personal USB stick, to £39.50 for the 4GB professional device reviewed here, up to £470 for the monster 6TB drive or £691 for a USB 3.0 external SSD (prices taken from a popular online retailer). The cost strikes me as reasonable for well-made secure storage.

More information on DatAshur is here.

On Bitcoin and the future of digital currency

Last week I attended the Pioneers Festival in Vienna. One of the topics was Bitcoin, a peer-to-peer digital currency based on cryptography and distributed transaction records. The number of Bitcoin is limited to about 21 million, of which over 14 million have already been “mined”. The word mining is somewhat deceptive; miners do not discover bitcoin exactly, rather they are rewarded for solving hard mathematical problems that confirm the validity of a block of Bitcoin transactions. The system provides for a decreasing number of Bitcoin to be generated until 2140, following which miners will be rewarded by transaction fees; at least, that is the idea as I understand it.

Bitcoin is interesting on multiple levels: mathematical, political, financial and practical. The currency has real value, but this tends to be volatile; it is widely enough accepted to be useful, but not enough that you can be sure of its future. There are intense debates even within the Bitcoin community about what should happen to it technically (forks are under discussion) and the extent to which it is safe from manipulation. There is a strong incentive to get in early on any Bitcoin alternative since it would be so profitable.

At Pioneers Bitcoin evangelist Roger Ver spoke and gave away $125 worth of the currency during his talk; he also gave me $5.00 when I spoke to him later. He describes himself as a Bitcoin investor, meaning one who invests in Bitcoin initiatives as well as hoarding the currency itself. That Ver predicts a bright future for Bitcoin is as surprising as the sun rising; his world depends on it.

Ver is also a libertarian who did jail time for selling explosives on eBay and renounced his US citizenship; you can read his own account of the incident here, where he adds:

Currently, I am working full time to make the world a better, less violent place by promoting the use of Bitcoin. Bitcoin totally strips away the State’s control over money. It takes away the vast majority of its power to tax, regulate, or control the economy in any way. If you care about liberty, the nonaggression principle, or economic freedom in general you should do everything you can to use Bitcoin as often as possible in your daily life.

The implication is that if you believe that taxation and regulation are not entirely evil you may be wary of Bitcoin, either because of worries over its use by criminals (it is commonly requested for the payment of ransoms by the purveyors of ransomware like Cryptolocker, for example), or through concerns that regulators, banks and governments may try to make it an illegal currency if its usage grows, or try to find ways of regulating it that remove its advantages.

Another possibility is that Bitcoin will be replaced by some other digital currency and lose most of its value.

Nevertheless, the ability to send digital cash to another person anywhere on the internet without involving a bank or a currency exchange is a powerful and disruptive concept.

Bitcoin in practice

What about the practical aspect of Bitcoin? If you want to try it out you can take a look here. There are several problems confronting the ordinary person who wants to get started, including which Bitcoin wallet (a means of holding Bitcoin) to choose and how to acquire some currency. Lack of regulation means that you either have to trust a web entity to hold your Bitcoin for you – perhaps losing it if the site gets hacked – or hold it yourself, which requires good backups and strong security since your own computer might get hacked and your Bitcoin stolen. Alternatively you can maintain low balances so that not much is lost if the worst happens.

Once you get set up though, Bitcoin is useful. Using Bitcoin, you can make payments with either zero or very low fees either for sender or recipient. Payments are non-reversible by design. Bitcoin is ideal for micropayments, and some companies prefer it for that reason. At Pioneers I met Parkt, which runs a scheme enabling one or more retailers to pay for your parking if you shop at their stores. They like Bitcoin because it is cheaper for them.


Bitcoin is also good for international payments since it is internet-based. There are some win-win scenarios, like the ability to purchase Amazon gift vouchers at a discount, said to be around 20%. The way this works, I was told, is that some workers for Amazon’s Mechanical Turk service (perform tasks for payment into your Amazon account) have difficulty converting their Amazon balance into cash. They can buy Amazon gift vouchers though, and sell them at a discount for Bitcoin.

How is Bitcoin doing? Its value has been stable since the beginning of the year, but it has fallen in value substantially since its peak in November 2013. Here is the chart for the past year:


At this point, all you can say for sure is that the future of Bitcoin will be interesting to observe.