Safe = Encrypted Data
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What is Encryption?
The word encryption comes from the Greek word kryptos, meaning hidden or secret. The use of encryption is nearly as old as the art of communication itself.
As early as 1900 B.C., an Egyptian scribe used nonstandard hieroglyphs to hide the meaning of an inscription. In a time when most people couldn’t read, simply writing a message was often enough, but encryption schemes soon developed to convert messages into unreadable groups of figures to protect the message’s secrecy while it was carried from one place to another.
The contents of a message were reordered (transposition) or replaced (substitution) with other characters, symbols, numbers or pictures in order to conceal its meaning.
Why Use Encryption?
History of Encryption
In 700 B.C., the Spartans wrote sensitive messages on strips of leather wrapped around sticks. When the tape was unwound, the characters became meaningless, but with a stick of exactly the same diameter, the recipient could recreate (decipher) the message.
Later, the Romans used what’s known as the Caesar Shift Cipher, in which each letter is shifted by an agreed number. So, for example, if the agreed number is three, then the message, “Be at the gates at six” would become “eh dw wkh jdwhv dw vla”. At first glance this may look difficult to decipher, but juxtaposing the start of the alphabet until the letters make sense doesn’t take long. Also, the vowels and other commonly used letters like T and S can be quickly deduced using frequency analysis, and that information, in turn, can be used to decipher the rest of the message.
The Middle Ages saw the emergence of polyalphabetic substitution, which uses multiple substitution alphabets to limit the use of frequency analysis to crack a cipher. This method of encrypting messages remained popular despite many implementations that failed to adequately conceal when the substitution changed, also known as key progression. Possibly the most famous implementation of a polyalphabetic substitution cipher is the Enigma electromechanical rotor cipher machine used by the Germans during World War II.