60 Years of Cryptography, 1949-2009 104
Dan Jones writes "2009 marks 60 years since the advent of modern cryptography. It was back in October 1949 when mathematician Claude Shannon published a paper on Communication Theory of Secrecy Systems. According to his employer at the time, Bell Labs, the work transformed cryptography from an art to a science and is generally considered the foundation of modern cryptography. Since then significant developments in secure communications have continued, particularly with the advent of the Internet and Web. CIO has a pictorial representation of the past six decades of research and development in encryption technology. Highlights include the design of the first quantum cryptography protocol by Charles Bennett and Gilles Brassard in 1984, and the EFF's 'Deep Crack' DES code breaker of 1998."
Re:Caesar (Score:5, Informative)
Though that might had happened earlier than the summary suggests...from http://en.wikipedia.org/wiki/Biuro_Szyfrow#Enigma_solved [wikipedia.org] :
Rejewski made in December 1932, according to historian David Kahn, one of the greatest advances in cryptologic history by applying pure mathematics group theory to breaking the German armed forces' Enigma machine ciphers.
BTW, since most of you are unlikely to read the whole wiki article, there's one very amusing part... ;p
On September 17, as the Soviet Army invaded Poland, Cipher Bureau personnel crossed the southeastern border with other Polish military and government personnel, into Romania. They eventually made their way to France where, at "PC Bruno", outside Paris, they continued breaking German Enigma traffic in collaboration with Bletchley Park, fifty miles northwest of London, England. In the interest of security, the allied cryptological services, before sending their messages over a teletype line, encrypted them using Enigma doubles. Henri Braquenié often closed messages with a "Heil Hitler!"
What? (Score:3, Informative)
> Unfortunately this machine ended up on the losing side of the war, so a lot of the
> knowledge will have been lost thanks to that.
Er, the German guy who invented the Enigma was killed in a horse carriage accident in 1929. So, no, the war had no direct effect on cryptographic knowledge in the way you imply. Considering the enormous number of casualties on both sides, however, I'm sure it affected it in a general way.
Re:How come? (Score:5, Informative)
The British came up with public key encryption [nytimes.com] well before Diffie & Hellman but since the work was for the secret service it was all highly classified. The work belonged to the government and couldn't be patented for profit as RSA has been. Bit hard to be part of history if it's all totally hush hush.
Can't remember where I heard this, some Discovery channel programme probably, but the guy that did a lot of the work wasn't allowed to take anything out of the secure building he worked in and nor was he allowed to write anything down so alledgedly did all his mathematical work in his head. Bit hard to believe really but not that implausible.
Bell labs (Score:4, Informative)
In fact, as is well known, A M Turing worked at Bell for a short time during WW2. He also learnt at Princeton the electronics that made the Bombes possible.
Modern cryptanalysis was a US/UK cooperation with information and development coming from both sides The Poles obtained an Enigma and started the mathematical theory of decrypting Enigma messages: the analysts at Bletchley, of whom Turing was only one (remember I J Good, anybody?) too it forward, and then post-Pearl Harbor it became (at least in part) a joint venture. It isn't necessary for the US to pretend that they did it all by themselves; we associate that kind of insecurity with the Soviet Union.
The (US) guy who recently wrote a history of D-Day (sorry, forget his name) writes somewhere that while the perception that in WW2 the British had the ideas and the US provided the productive capacity is not really correct as it stands, there is some truth in it. That should really be good enough for everybody.
Re:How do you know when you've decrypted something (Score:1, Informative)
Statistical analysis.
Properly encrypted material with a good pseudo-random number generator should appear essentially statistically identical to random white noise. Decrypt the material and the statistical analysis should show something dramatically different from random white noise.
Re:How do you know when you've decrypted something (Score:5, Informative)
Decryption is a mathematical operation. You are given a blob of yunk. You can be fairly certain it is encrypted with a given cipher because it meets certain characteristics - either length, or hash-depth, or there is a header or footer of a given length, or some revealing information about the cipher may have been sent prior to or alongside the encrypted blob.
Then, if you're smart enough, or you have enough money, or time, or computing power, or a lot of luck, the decryption operation might occur. You can check as to whether or not you've successfully decrypted the data mathematically - e.g. does the result set fit with the function I've just run and give me the source data I started with? If so, yes, you've decrypted the data.
It's your responsibility as a researcher to decide what to do with whatever came out the other side. You may have to decrypt it again before proceeding. You may find out that what you just decrypted was nothing more sinister than ICMP_FRAGMENTATION_REQUIRED (Frak!).
The holy grail of cryptography may infact be steganographical encryption - or binary / machine language that reads as Grandmother's Cookie Recipe, but when run as an executable it actually glasses the machine. Who knows?
Cool Enigma Facts (Score:3, Informative)
Couple of cool things to know about the Enigma:
I believe it was the first machine to have symmetrical encoding and decoding. Because it had a this property (as a letter was coded through the rotors, there was a rotor that reflected the encoding back through the rotor stages again), an operator could code and decode messages without reconfiguring the device.
Due to the fact above, the Enigma could never encode a letter onto itself. This greatly decreased the permutations allowed and made the device less effective.
The way the Germans used the machine also made the device easy to crack. Operators would encode the rotor setup in the message. This allowed verifying that the right settings were being used. Also, the Germans would include many standard phrases like praise for the Fuhrer.
Though the Enigma machine is the most well known device, there were many rotor based encoders during the WWII and post era.
There are many simulators of the Enigma machine (see the Wikipedia article). Very cool to play with to really understand the operation of the device.
Re:Cool Enigma Facts (Score:2, Informative)
I believe it was the first machine to have symmetrical encoding and decoding. Because it had a this property (as a letter was coded through the rotors, there was a rotor that reflected the encoding back through the rotor stages again), an operator could code and decode messages without reconfiguring the device. Due to the fact above, the Enigma could never encode a letter onto itself. This greatly decreased the permutations allowed and made the device less effective.
I may be misunderstanding your cause and effect combination slightly here, but the symmertical encoding/decoding did not cause Engima to never encode a letter onto itself; that was specifically because of the reflector cog at the end of the wheels and the design of the electrical circuit within the machine.
Operators would encode the rotor setup in the message.
Twice (in case there were problems in receiving the messages); this led to the British and Polish (who never get enough public credit, IMO) knowing, for example, that if the message started 'ABCDEF', then A and D were the same original letter, and likewise with B/E and C/F. Herivel should also be credited with his work in predicting the rotor setups based on relatively simply psychology
Also, the Germans would include many standard phrases like praise for the Fuhrer.
Of more use was a certain weather station that broadcast messages at a set time every day and started each with 'WETTER'.
There are many simulators of the Enigma machine (see the Wikipedia article). Very cool to play with to really understand the operation of the device.
Writing one helps you appreciate it even more [suitcase.org]. Even the rotation of each cog isn't as simple as it seems.
Re:How do you know when you've decrypted something (Score:2, Informative)
"Encrypted twice" doesn't mean anything. A composed encryption scheme is a single function, same as y = (2x + 1)^2 - 4.
Technically true, but depending on the cipher(s) you use, you may have no idea at all what the resulting function is, and it is therefore often easier to decrypt in the same steps you used for the encryption.
Some cryptographic functions, RSA for instance, are mathematical groups. In other words, RSA(RSA(plaintext, key1), key2) === RSA(plaintext, key3) for some key3 that you probably don't know. In such cases, if you were trying to break the cipher and had no means to recover keys 1 and 2, it would be easier to discover key3 and decrypt in one step.
That's not true for all ciphers, however. DES is one example of a cipher that is not a mathematical group, which is why "TripleDES" is regarded as being more secure than a single pass of DES -- I believe the assumption is that 3 passes of 56-bit DES are about equivalent to a 112 bit key.
All of that theory, of course, breaks down if you can get at the original keys. Rubber-hose cryptanalysis has the obvious advantages of being fast and computationally cheap.
Re:How do you know when you've decrypted something (Score:3, Informative)
While f3(x) may well be stronger than f1(x) or f2(x), this is not necessarily the case.