We now know that GCHQ has a perverse interest in our lives. But what we don't know -- and what is arguably more important, as dedicated taxpayers -- is whether or not the government's getting value for money.
Let's start with the easiest thing to work out: storage. According to the Guardian, GCHQ has taps on 200 fibre-optic pipes, each transmitting an average of about 10 gigabits per second. That works out as being 21.6 petabytes per day of stuff.
Now, we also know from the Guardian that the fine folk at GCHQ store content for three days, and metadata for 30. That's where this gets expensive. The three days of content is obviously the biggest storage headache, taking up an estimated 64.8 petabytes; but the metadata also sucks up a surprising amount of space.
Going from the results of this study from Microsoft, metadata makes up about 4 per cent of the entire file size for most desktop files, images and the like. In the absence of any better number, we'll run with that; given that GCHQ stores the metadata for 30 days, that's another 25.9 petabytes of storage.
All in, we're looking at 90.72 petabytes of storage, which is a lot. From hunting around the web, it looks like you can get storage from anything between 5 - 25 pence per gigabyte. Now, GCHQ is a government department, so it's going to want value for money; however, you also need all of your data about other people to be secure and well backed up, so no skimping here. Taking a value of 12p per gigabyte -- which is what Gizmodo UK hosters Rackspace appear to charge -- that means GCHQ's monthly storage bill is a fairly hefty £11,415,217 and 77 shiny copper pennies.
But storage is just the tip of the iceberg. Network bandwidth is also a massive cost. Assuming that GCHQ doesn't have direct fibre lines from its taps into its data centres (not impossible by any means), network bandwidth runs around £0.08 per gig. At that same turnover rate of 90.7 petabytes a month, we're looking at a painful £7,610,145.18 per month just to move all the data into the NSA's storage centres.
Running total: £19,025,362.95
But we also know from the Guardian that GCHQ analyses all that data in real time. That's 2,000 gigabits of data to be searched for keywords, which takes more than just a straight-six under the hood. Although data on how much power it takes to spy on a nation isn't freely available, there are a few projects like SETI and the Large Hadron Collider that spew out lots of data that needs computer analysis.
Take the numbers from the LHC: 15 petabytes of data are analysed per year, using a network-connected 'supercomputer' running at 7 teraFLOPS (FLOPS stands for Floating Point Operation Per Second). The numbers from SETI are in the same ballpark. Granted, the type of analysis done there is rather different -- and GCHQ may well have a more efficient way of trawling thorugh -- but it's the best data we've got.
Scale that up to the 21 petabytes per day that GCHQ run through, and you're looking at around 2.5 petaFLOPS of computing power needed to search, index and analyse all the data.
In order to do that, GCHQ would need a bona-fide supercomputer. A similar machine, recently built for the energy company TOTAL, cost £50 million and took four years to build, with 110,000 cores and 54,000 GB of memory. Given that GCHQ is meant to protect us from cyber-crime, it's definitely not a stretch to imagine it has such a machine.
Running total: £69,025,362
And let's not forget about running costs. The electricity, depending on which part of the UK GCHQ has secreted its machine in, will cost about £1,141,100 (based on energy costs of 9p per kWh).
Running total: £70,166,462
Then there's the human element. The Guardian revealed that GCHQ has 300 analysts working full-time on trawling through the data produced by the wiretaps. Although the GCHQ careers site is 'conveniently' down at the moment, we know thanks to this Telegraph article from a little while ago that a starting salary for an analyst at GCHQ is about £25,000. Accepting that the newbies probably won't be working on the top-secret stuff, and that Glassdoor reckons an intelligence analyst makes £30k a year, and that's the sum we'll go with. At 300x£30,000, that's a payroll cost of £9,000,000 per annum.
Running total: £79,166,462
BUT WAIT: Of course, there are also the costs of the back-office staff -- the arse-covering lawyers, HR bods and IT dudes, not to mention cleaners and security staff. This utterly enthralling document (entitled Back Office Benchmarking Analysis 2008-2009) seems to suggest an average 28 per cent extra spent of back-office functions for every 'frontline' service; so in this case, that's another £2,520,000.
The bottom line: £81,686,462
GCHQ's individual budget isn't public knowledge, but its funding comes from the Single Intelligence Account (SIA), which for 2012-13 is set at £2.1 billion. There's also a £650 million government slush fund set up to counter cyber security. Given that, it's easily believable that GCHQ was able to sling £80-odd million into its flagship snooping programme.