Cryptography: The Art of incomprehension by others.

Cryptography: The Art of incomprehension by others.

Ever since the dawn of history, man needed to protect documents and communications from the eyes and ears of opponents or enemies. Since 1900 B.C, the pharaohs used different hieroglyphs to communicate with their generals. 4000 years later Americans during World War II recruited hundreds of Navajo Indians as operators in radio communications. Thanks to their language incomprehensible made military communications secure in the case of tapping by the Japanese.

History and the Future.

Today cryptography, or the ability to make a message incomprehensible to everyone except the legitimate recipient, is a true science. Below we are presenting a short journey into the history of mystery, maths, and espionage to find out how a cryptosystem is created and how it is used. Which are the safest systems? And how the contribution of an unknown Polish mathematician determines in the fates of World War II. But do not forget that to discover something very private, it is not always necessary to have access to a computer or to an advanced encryption system. Sometimes it’s enough to put to work the intelligence and the trust.

Cryptography: The Art of incomprehension by others.

Millions of messages permeate each day telecommunications networks. Every day over 150 billion e-mails and 400 million Twitter messages are sent (see for curiosity the statistics of worldometers). E-mails and messages, but also banking transactions, telephone calls and even faxes (still). Whose content often needs to be protected from unauthorized interception: from the number of credit cards to conversations among politicians.

Protection and communication.

The protection of these communications is entrusted to a special technique called cryptography. The term comes from Greek, from the union of words cryptos (hidden) and grams (write), secret writing. Cryptography is the art of sending messages (and not just in writing) accessible only to the right recipients.

About 400 BC the “sensitive” communications were coded with the skit method. A simple and effective system that for the first time introduced the concept of the decryption key. The message was written from left to right on a leather strap wrapped around a rod so that every row of the stem contained only one letter. If the scroll was opened, the letters were reorganized and the message was no longer readable.

Only using a stick identical to that of the sender (key) would enable the recipient to rebuild the message text. In Sparta, this system was used since 400 BC. It is probably the oldest known method of cryptography through transposition. With small changes, this method survived for many centuries alongside the most naive systems. For example, replacing or mixing fonts based on not too complex rules so that the recipient itself could decrypt the message.

When the enigma becomes art.

Cryptosystems based on replacement of letters were very unreliable. In the early 1930s, German intelligence created the electro-mechanical encryption machine called Enigma. It was a separate typewriter equipped with three different wheels, each of which listed the alphabet characters in a predefined way, and different from that of the standard.

Cryptography: The Art of incomprehension by others.

The first wheel was connected to the stylus keys and reproduced the text by coding it simply by replacing the default key. The encoded text was re-coded by the second wheel with a different key, and then again by the third. Additional mechanisms could then interfere with other codifications. To decrypt a text encoded by Enigma, it was necessary to have another Enigma machine configured exactly as the first. The latter were pre-selected before the machine distribution.

This was a terribly complex mechanical system that functioned in such a complex game of espionage and counter-espionage. The system was first broken in 1932 by Polish mathematician Marian Rejevski, thanks to the help of the French and Polish secret service. The Germans responded by making the mechanism of the system more complex. But, this evolution of the Enigma was finally broken by Alan Turing.

Old methods and new methods.

Although these encryption systems are overseen by complex algorithms, they are meant to be broken. A modern computer can decode without difficulty a message encoded by Enigma. This, simply by trying to break down one of the all possible keys. In a few weeks, it would use all the options to unlock the code.

For this reason, in the mid-1970s, Whitfield Diffie and Martin Helman, two American scholars, built a cryptography system based on the use of two different keys, designed to depend on each other. The two codes are familiar with their public and private key names. The first used to encrypt, the second to decrypt.

Who needs to communicate in secret, suffices to encrypt the message with the public key of the recipient. The latter can then decrypt the message using its own private key. Everyone should, therefore, distribute their public key to all people from whom they should receive encrypted communications, without worrying about their privacy, while reading is only possible through encryption of messages.

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