Classic Cryptography   Transpositions   Double Transpositions   Pig-Latin   Grille   Vigenere   Caesar Substitution   Atbash   Playfair   Bifid   Monoalphabetic     Substitution   Pig Pen   Map Cipher   Diagraphic Substitution   Jefferson Cipher   Polybius Chequerboard Key-Based    Encryption Glossary Basic Concepts in Data Encryption: Classic Cryptography Double Transpositions Double transposition ciphers are very similar to normal transposition ciphers but are more complex in their design and are harder to decipher. Observe the diagram below and note how they differ only slightly. There are also multiple methods for creating a double transposition cipher. One example is shown below: Start with a keyword such as "encrypt." A matrix grid is created below the keyword and the secret message is written in from left to right. An order of sequencing to the columns or rows in then assigned into the matrix grid. In the example below the cipher is made more difficult by ordering the columns out of order, that is, unlike transposition method illustrated above, it does not follow the alphabetic order. The letter "Z" is used to fill in blank spaces found inside of the matrix. Each column or row, in numbered order, is then written down in blocks of 3 to 5 letters, in all uppercase, to encipher the message. Plain Message: 'Welcome to the exciting world of encryption'. Enciphered Message: OENOPZ EOIRCN LTTLRZ WTCONO CHIDYZ MEGFTX EXWEIZ Why is the enciphered message in all uppercase? If one is observant enough, it is apparent that a case sensitive text would at least give away the number of words that are contained in the message, not mentioning much more steps which become unnecessary as one tries to decipher it. Copyright ©1999 ThinkQuest Team 27158 — Developed for ThinkQuest 1999