Friday, 29 April 2016

Lines of defence #IPBill

Encryption is all about keeping your information (e.g. stored data or communications) secure from attack, i.e. so that nobody else apart from those you intend can get access to it.

Technical attack

The first, and most obvious, line of defence against an attack is against the technical aspect of the encryption itself - an attack on the maths. You need systems where it is not possible for a computer to try every password in a few seconds, or where there are not mathematical tricks to extract the data.

It is fair to say that modern encryption systems are pretty good at this and getting better all of the time. This is the main thing people think of when considering the defence against attack.

However, as xkcd make very clear, tackling the mathematics is not how you attack good encryption. The "$5 wrench" is much more effective, sadly. So we need a defence against that.


One of the first things to consider is whether someone can detect you have something encrypted in the first place! If they cannot tell you have something encrypted, then they will not try and force the keys out of you with a $5 wrench!

There are several techniques for this. They generally rely on the fact that modern storage devices and things we store have spare space. So on a hard drive, you may have terabytes of space and actual content that is only a hundred megabytes. What is in the rest of the space? Well, it can be random data and nobody will think it is anything else. Except, if you know the right key you can turn random data in to an alternate file system with stuff on it. Drives have random data padding, or can, so you have some degree of plausible deniability.

Another, perhaps safer, system is using the random elements in some types of data. Audio, video, images, all have low levels of random noise. By replacing this with encrypted data, which looks like random noise, the images all look pretty much the same, but can be decoded. The nice thing is, as long as they are original recordings (so no reference to which they can be compared) there is typically no way to prove the "noise" is encrypted data and not "random" without the key. Again, plausible deniability.


Another simple approach, which may mean the $5 wrench gets re-applied, is that you can have a system were there is a duress code which, when used, wipes the data. You may think that it is hard to quickly wipe a hard disk, or that the hard disk can be copied first so you can always try again, but there are simple ways around that. The idea is you have a security device that holds the (long, and random) key used on the hard disk. It needs the code to extract the key to decode the disk. But, if given the wrong code, it wipes the key (which is quick and easy). It cannot be copied and has tamper detection as well, so trying to open it causes the key to be lost anyway. Apparently iPhones have this sort of technology now, but I don't think they have a duress code (yet) just the "wipe after a number of wrong attempts".


Another cunning plan in that the encrypted data is arranged such that with one key you get the actual stored data, but with another, you get some benign data - though ideally the benign data wants to be something embarrassing that you might have wanted to encrypt. This is harder to do, as the data has to be somewhere, but with things like alternative file systems in hidden partitions, as above, it means that application of the $5 wrench can get access to encrypted data that "they" were sure was there, but not get the data you want to keep secret.

When it is not a $5 wrench

All of this is trying to address the adversary that is wanting to get to your data, on the assumption that they are "the bad guy". But what if the data is something you want to hide because you are a criminal?

Well, the problem is that every one of these techniques, designed to protect us against "the bad guy with the $5 wrench" work just as well to protect us from the FBI or the police. They will use threats of law enforcement, imprisonment, and so on, rather than a $5 wrench, but the answers are the same. If you can make it so they have no way to know there is something hidden at all, you win. If you can make it so after threats, you give a key that provides non-criminal data, you win. Even the duress code to wipe the data may work, if it does not flash up saying "wiping key" and just says "invalid code" and you can claim you really have forgotten the key.

The protections are the same, and so, if we are to continue to mostly win against the "bad guys" we will have systems that win against the police as well. That is just a fact of life, without which we open doors to criminals (and $5 wrenches). Sadly, maths does not understand law, and law should realise this and jus get over it and stop being an arse.

Wednesday, 27 April 2016

So, I'll try contacting Lord West #IPBill

Dear Sir,

I have heard some of your comments in the Lords, on parliament TV, and I would like to try and impart some technical knowledge to assist you in your work, if I may.

One of the key points you make, quite strongly, is that there should be no way that terrorists, pedophiles, criminals, should be able to communicate such that proper authority cannot by some means monitor what they say. No "safe places" for them.

I fully understand that the monitoring of communications is carefully controlled with safeguards and oversight to ensure such an intrusive power is used where necessary against such serious crimes.

However, I feel you may lack some understanding of basic mathematics of encryption.

It is a simple matter of fact that it is possible for two people to communicate in a way that is totally secret. Whilst computers make this easier, it can be done with no more then pen and paper and dice. It would allow secret messages that can only be read by the intended recipient, and not by GCHQ or NSA no matter how much resource they throw at it.

This is a fact - it is a fact of life and mathematics. It is not changed by speeches in the Lords or legislation.

Indeed, with the help of computers, it is possible for such communications to be embedded in random data in images and videos in such a way that it is mathematically impossible to prove there is a message being conveyed. So even outlawing such communications cannot be detected or enforced.

I will be more than happy to visit you and explain these basic principles, and even demonstrate pen and paper encryption to you. I also have some videos on the matter if you are interested.

Given that this is a fact of life, a reality, can you perhaps concentrate your efforts on the negative side effects of Draconian laws to stop people communicating. Criminals can communicate, end of story. All such laws do is impact those of us that choose to abide by laws, and in doing so we open ourselves to criminals attacking us.

Please do take this email seriously. I am a technology expert. I have given oral and written evidence to the committee on the IP Bill. I run training courses on this. I write code for a living and I run an ISP. I can help you understand the issues, and perhaps the serious negative side effects, of your views.


Adrian Kennard
Director, Andrews & Arnold Ltd.

Good question from @LordStras on #IPBill today - shame about the answer!

Lord Strasburger asked at 15:20 today:

My Lords, paragraph 217 of the Investigatory Powers Bill gives the government almost unlimited powers to force, in secret, companies to, I quote: "remove electronic protection" from their products. Could the minister tell the house how the government intends to use this power in the increasingly frequent case where a company has designed the security of its products so that even the company itself is incapable of unlocking the equipment or decrypting the data. Will Apple, and others, be require to redesign their products so that they can break in to them, or will they be required to stop selling them in the UK?

Lord Keen seems to totally miss the point, and ends up, after several questions, stating: There is no question of encryption keys being weakened. There is no question of encryption keys being made available in response to a warrant. The encryption key would remain wholly in the possession of the provider of the service. The warrant will ask that they apply the encryption key in order to provide the decrypt. So there is no weakening of any encryption in these circumstances.

I am sorry, but (a) why can they not answer a straight question, and (b) do they really not understand?

A company can make their communications system, like Apple with iMessage, so that Apple do not have the keys to decrypt the communications. So that the key does not "remain wholly in the possession of the provider of the service" and so that it is not reasonably practicable for them to decrypt the messages.

The question is whether paragraph 217 could be used to force a company to redesign such a system so that they do have access to keys. The problem is that if they do this they are weakening the encryption system. They are not following best practice. They are making the communications more vulnerable to attack.

Think about it for a second - any step that changes from "government cannot see message" to "government can see message" (even under strict rules) has to be a step to weaken the encryption in some way. One more person being able to see the message means it has weaker encryption.

Lord West goes on to repeat the stupidity of saying that there can be no place for terrorists and pedophiles to communicate - as if he wants to outlaw multiplications. As I have pointed out so many times, anyone, with no more than pen and paper and dice, can send secret communications without a "service provider" providing the encryption, and without a way for GCHQ or NSA to crack the encryption. That is a fact of life and mathematics and no amount of legislation or speeches in the Lords can change that. Get a clue Lord West, please.

Tuesday, 26 April 2016

More on SciFi: Stargate communications stones

I am watching Stargate universe (SGU) again, why not, and they make extensive use of the "communication stones".

These allow two people to swap bodies over any distance. There is a device that handles the stones, and they can be disconnected. Interestingly the link is disrupted when one end going in to, our out of, FTL (Faster Than Light) travel. The connection breaks totally if one side goes through an intergalactic gate...

One of the odd things on this plot device is the issue of what happens if someone dies?

The plot is that normally there is no physical effect on one side yay effects the other, so lack of sleep, caffeine, food, etc, does not impact the other person, but death and near death does! If one end dies, both die.

I was thinking, why would this be? The mind swap seems pretty absolute, so one end dying should leave the other end stuck in a transferred state, surely?

Well, I forgot the Terry Pratchett narrative imperative...

If the communications stones allowed any way for the swap to be permanent, even with one party dying to make it so, it would create a massive plot device. Any person can extend their life by simply swapping with a younger person and then getting killed. It would break the normal flow of most fiction - you cannot easily have immortals in a story line (Dr Who excepted).

So that is why both ends have to die, no matter how illogical that may seem.


Number porting update

Just a quick update - thanks to all those that have emailed in - we'll be in touch as soon as we can start trials.

So far it seems BT may possibly have a bug in their order processing that means these orders just don't work. We are trying to get that fixed now. It does kind of suggest this will be a pretty unique offering though. So I'll update when we know more.

Update: BT a/c manager has confirmed: "I do have access to a Openreach specialists who can help us with the questions that are raised. He has informed me that the renumber for exporting is a current process then in theory should work." so we are not going mad, this should indeed work. Working with BT to get it fixed now.

Monday, 25 April 2016

European Convention on Human Rights

I was shocked when Cameron was saying we need a new Bill of Rights to replace this, and then this week was more shocked when I hear Theresa May wants us out of the ECHR.

If Government, or MPs, want to reduce or remove human rights to get around what they want to do, it says a heck of a lot about what they want to do!

But I have to say that when someone like Patrick Stewart steps in and does something like this, it really shows the problem so well. This is gold. Life of Brian classic, but a serious point. Very serious.