Don't read this. The Internet is not secure.

"Snowden", "surveillance", "Islam" , "bomb", "terrorist". That's all it takes. Those key words, written in any order on an email - or indeed this column - could be enough for my name to be identified as a 'person of interest' by the security services of the United States of America or Great Britain. Probably both.

Indeed, if you are reading this on the internet, you might well be alerting the attention of some internet 'bot' somewhere in cyberspace, which will by now have logged your IP address, traced your browser history and even had a peek at your email inbox.

The consequences could be quite profound. You might be held at an airport, denied a visa to travel. You might find yourself held for questioning by the police for nine hours with no explanation. Threatened with prison if you don't divulge all your internet passwords.

Paranoid? Absolutely. But that is the world we are now living in, where it must be assumed that everything you do or say on the internet or on the phone is being monitored. Perhaps not by some PC plod on headphones as of old - those of us brought up on television series like The Wire have a very antiquated notion of what surveillance means in the digital age. Now it is all done automatically, anonymously, by computer programmes that search millions, even billions of digital messages in seconds.

The Home Secretary Teresa May made clear yesterday that, under her interpretation of Schedule 7 of the Terrorism Act, any individual may be detained by the police merely on suspicion that they  possess information that might be of use to terrorists.   I could hardly believe my ears. That is very close to the definition of a police state.

 It may not seem a great hardship, to be detained at an airport and questioned. But anyone who has had experience of interrogation will tell you that a lot can happen in nine hours, and the psychological stress is intense. This is supposed to be a free country. It is shocking that a citizen can be held and interrogated when there is no evidence that he or she is engaged in acts of terrorism - and in the case of David Miranda, the Brazilian partner of Guardian journalist Glenn Greenwald, there was none.

We are now being told that Mr Miranda, was not an innocent citizen but a "mule" carrying security sensitive material on behalf of the Guardian newspaper. What a ridiculous concept:  to equate journalism with drug trafficking! It is also said that he was "uncooperative" and "asked for his own lawyer". Good for him.

No free citizen should be forced to co-operate with police going on a blatant fishing expedition, as even the Labour Peer Lord Falconer - who was Lord Chancellor in the government that passed the Terrorism Act 2000 -  made clear yesterday. What we are seeing now looks very like a campaign of intimidation of the press.

What point was there in sending Britain's top civil servant, Sir Jeremy Heywood, to witness the Guardian editor, Alan Rusbridger, destroying computer hard disks containing material which had already been duplicated and lodged in the 'cloud'? There was none - except to make the point that newspaper editors are now targets of the state apparatus. It was sinister theatre. A warning that editors are in the judicial firing line.

The disks contained material leaked by the ex-CIA whistleblower, Edward Snowden, who has revealed in exquisite detail the methods and the manner of internet surveillance by the NSA and our own GCHQ. The state has acquired the power, which is technically illegal under the US constitution, to monitor telephone records from mobile phone companies like Verison. Internet giants like Google and Facebook have been collecting data under a secret surveillance programme called Prism and allowing access to spooks.

The UK government's monitoring station, GCHQ in Cheltenham has been tapping into the fibre optic cables that carry global communications in and out of the country and sharing the data with the NSA in the US. This allows the National Security Agency to get round America's privacy laws because it can say it has not been directly involved in accessing the emails of US citizens. A programme called XKeyscore boasts of having accessed 42 billion records during a one month period in 2012.

Now, I am an old analogue hack who finds all this baffling. I can scarcely get my own computer to work, let alone understand the countless ways in which the digital age has turned into an Orwellian dystopia. Technology changes so fast that the techniques identified by Snowden, (now holed up in Russia hoping to avoid the 35 years handed out to US army whistleblower Bradley Manning yesterday) are probably already obsolete.

Snowden may even have misunderstood the reach of the technology he was using as a relatively lowly CIA operative. He boasted that from his own desk he could monitor the emails of the President of the United States by filling in a simple online form. That has been challenged by others in the techy world.

But we know from the reaction of the state agencies that much of what he has claimed is going on, is going on. There have been no categorical denials, though the internet companies insist they have acted within the law. President Obama has said that there is a balance to be struck between security and privacy - in other words, watch your back. Governments now employ some of the best computer hackers in the world, and they know how to know everything.

The paralegal website, Groklaw, announced this week that it was closing down because it could no longer guarantee the anonymity of its contributors. Lavabit, the encryption site used by many journalist has also shut up shop after 10 years because its founder, Ladar Levison said email can no longer be trusted.

Journalism is changing as a result. Investigative journalists are now being advised not to use email, social networking sites or even the phone, but to rely on face to face meetings and hand-written notes. This is something the new generation of digital journalists finds hard to get their heads around. They are used to doing almost all of their work on line, using twitter feeds, email and countless informal networks often based on Facebook.

But it is now clear that - as gmail admitted last week - none of this is private. All of it is potentially under the scrutiny of the surveillance state. Nothing is secure, not even encrypted messages, which can be held by the NSA/GCHQ almost indefinitely and subjected to sophisticated methods of de-encryption. Indeed, encryption is tantamount to an admission of guilt to these people,

And how convenient, that the new media is shutting up shop, just as the old paper press is in financial crisis. Having extinguished privacy on the internet, the surveillance state is now screwing down the print media. The intimidation of journalists at airports is surely intended to prevent them transferring information physically without using email, Facebook, or any other compromised internet based mediums of communication.

I said in a column last month that the surveillance state had opened a digital window into our souls. Now it is reaching through it.