The Spartans in 400 B.C. used cryptographic system called scytale. It is cylinder shaped with leather wrapped around it with a written message In the 5th century, Greeks used enciphered warnings about planned surprise attacks The Greek historian Polybius introduced the Polybius’ checkerboard. Uses a form of substitution that pairs of numbers substitute letters

Caesar is well-known in two instances of enciphering: first documented cipher for military purposes in the Gallic Wars. Caesar Shift Cipher which replaced each letter with the letter three places further down the alphabet Battista Alberti invented a cipher wheel. It was the first polyalphabetic substitution. pher/

The first cryptanalysts were born among the Arabs around the 8 th century Islam extremists concealed their writings from the orthodox through encipherment The Subh al-a ‘sha is an Arab encyclopedia detailing all Arabic knowledge of cryptology

In Europe during the Renaissance, cryptography was becoming a routine diplomatic tool Cryptanalysis was moving into the West during the 15 th century time By the 18 th century the telegraph was invented. During the Civil War U.S. Military Telegraph Corps used route ciphers. Many cryptanalysists invented different ciphers between the 15 th and 18 th century periods: Giovanni Battista Porta ( ) invented the earliest digraphic cipher. Blaise de Vigenere ( ) invented the first acceptable autokey cipher system. Also the Vigenere Square. Francis Bacon ( ) invented the Bilateral cipher. Thomas Jefferson ( ) invented the wheel cipher. Charles Wheatstone invented the digraphic cipher (playfair cipher).

Notes/lectures/classical.html Notes/lectures/classical.html The code book: the Science of Secrecy from Ancient Egypt to Quantum Cryptography, by Simon Singh, 1999, Anchor Books phy phy Invitation to Cryptology, By Thomas Barr