I had a brief online discussion the other day with someone who doubted that it was worth encrypting anything as there was bound to be someone who would be able to access your data if they liked. The discussion was based around the case of Room 641A and the Government's internet surveillance. Of course it's true that the amount of computing power has greatly increased the chances of breaking ciphers via brute force methods. But to think it's impossible to have an unbreakable cipher is perhaps missing the point. Cryptography isn't a single puzzle to be unlocked, it's the aim of securing or concealing a message to anyone but the intended recipient - there are almost unlimited methods of doing this based on a variety of methods and techniques.
The techniques and methods of cryptography are also being continually adapted - the cipher that the German Kriegsmarine adapted in World War 2 is a long way from the simple substitution ciphers used by Julius Caesar.
The inventor of the Enigima cipher actually estimated that it would take 1000 skilled cryptanalysts armed with captured Enigma machines testing four keys a minute - approximately 1.8 billion years to test all possible combinations!
Now obviously modern day computing power would seriously reduce that - but it is also possible to add millions of more variations to Enigma fairly easily (adding extra rotors to the machine for instance).
But I think there is a better example in The Voynich Manuscript.
Now this is one book with a strange story, there are claims it was written by Leonardo De Vinci, Roger Bacon and that it contains a variety of hidden secrets. It contains 104 parchment folios separated into sections which appear to be on a variety of subjects - herbal, astronomy, biology, pharmaceutical and some sort of recipe sections.
But the real reason that this book is so mysterious is that nobody can read it. The entire book appears to be encrypted with some sort of unknown cipher, we only have a rough idea of the content from the hundreds of illustrations and symbols that appear on the majority of the pages.
Over hundreds of years right up to the present day many people have tried to crack the code and read the book. A couple of people have claimed to have succeeded although these have all been discredited. The book has been recently carbon dated by the University of Arizona who have asserted that it was written on pages created between 1404 and 1438.
But what secrets are contained in the text? It is generally agreed by cryptoanalysts that there is some form of readable text protected by some sort of cipher but until some one cracks the code then we can never be 100% sure. There are of course lots of rumors about the mysteries it holds.
However the crux of my point is that in the age of high powered computers and modern technology - this cipher has remained unbroken for over 600 years despite the best efforts of many. We now have the likes of Advanced Encryption Standard (AES) which is supposedly uncrackable if implemented correctly. Who knows if the NSA or similar have developed systems and procedures for deciphering information encrypted by their enemies. One thing is for sure though that breaking encryption which has been implemented correctly using a system such as AES is no trivial undertaking even if it is possible.
For anyone interested in reading more about the Voynich Manuscript - here's a great place to start -