S S O H S T P F O R I E E A E T Q N E T F A I X E G L F D R A U L R N O S R X L H A T R O To solve this cipher, read down the columns in this order 8, 1, 15, 2, 14, 3, 13, 4, 12, etc. A variation is to arrange the cipher so the columns are read upwards. Another is to arrange the ciphers so the columns are read alternately upward and downward. The factors of the number of letters in this case give the shape of the rectangle as usual. It will be seen that there are a great number of possible transposition ciphers that come under Case 1 but practically all of them are useless from a military standpoint because they do not depend on a key which can be readily and frequently changed. However such ciphers constantly crop up in cipher examination, being used for special communication between parties who consider the regular military ciphers too complicated. Thus some of these expedients have been used. Reversed Writing.--(Special case of Case 1-a). LEAVING TONIGHT is enciphered THGINOT GNIVAEL or it may be reversed by words, thus GNIVAEL THGINOT or by groups of five letters, thus IVAEL NOTGN XTHGI. Vertical Writing.--(Special case of Case 1-b). Same message is enciphered, LT EO AN VI and is sent, LTEOA NVIIG NHGTX. IG NH GT Case 2.--This case includes all transposition ciphers in which lines and columns of the text are rearranged according to some key word or key number. There are many varieties of this case but their solution usually is arrived at through the methods suggested for Case 1, that is, arrangement into appropriate rectangles and examination of lines and columns for words or syllables. Rearrangement of columns or lines follows until the solution is completed. Case 2-a. Message HIIGF TNGHI NTCVN IEIOT CYIFY LHAEA ESNBA EEEEN RWGBN YDELR OAESG RNEBO VNLDA ICAOA LCNDT IRGVA CDOIE SEREC DVPEI AFIFL RINEH ETT There are 108 letters in this message and examination shows it to be a transposition cipher, English text. The number of letters, 108, immediately suggests a rectangle of 12 × 9 or 9 × 12 letters. Put into this form we have: Vowels Vowels