San (letter) San (letter) San (Ϻ) was an archaic letter of the Greek alphabet. Its shape was similar to modern M, or ϡ, or to a modern Greek Sigma (Σ) turned sideways, and it was used as an alternative to Sigma to denote the sound . Unlike Sigma, whose position in the alphabet is between Rho and Tau, San appeared between Pi and Qoppa in alphabetic order. In addition to denoting this separate archaic character, the name "San" was also used as an alternative name to denote the standard letter Sigma. The existence of the two competing letters Sigma and San is
The Alphabet Cipher The Alphabet Cipher Lewis Carroll published "The Alphabet-Cipher" in 1868, possibly in a children's magazine. It describes what is known as a Vigenère cipher, a well-known scheme in cryptography. While Carroll calls this cipher "unbreakable", Kasiski had published a volume describing how to break such ciphers from five years earlier, and Charles Babbage had secretly found ways to break polyalphabetic ciphers during the Crimean War. The piece begins with a tabula recta. ABCDEFGHIJKLMNOPQRSTUVWXYZ Each column of this table forms a dictionary of symbols representing the alphabet: thus, in the A column, the symbol is the same as the letter represented;