A cipher where the letters of the plaintext are jumbled up. This is usually done in some systematic way so that the message can be decrypted by its intended recipient.

An example where the first, second, and third letters are each written on a separate line then repeat this pattern for the rest of the message.

The plaintext:

    Two tires fly. Two wail.
    A bamboo grove, all chopped down
    From it, warring songs.
The enciphering step:
T  T  E  L  W  A  A  M  O  O  A  C  P  D  W  R  I  A  I  S  G
 W  I  S  Y  O  I  B  B  G  V  L  H  P  D  N  O  T  R  N  O  S
  O  R  F  T  W  L  A  O  R  E  L  O  E  O  F  M  W  R  G  N
The ciphertext:
    TTELW AAMOO ACPDW RIAIS GWISY
    OIBBG VLHPD NOTRN OSORF TWLAO
    RELOE OFMWR GN
    

the haiku used above is from Cryptonomicon

Another type of transposition cipher uses a keyword. First choose a keyword where each letter is unique; in this example we'll use PRIVATE, which we'll use to encode the riddle: Feed me and I live, give me a drink and I die.

Arrange the letters of your message as a block underneath the keyword, filling in the block with dummy letters as needed:


    P R I V A T E

    F E E D M E A
    N D I L I V E
    G I V E M E A
    D R I N K A N
    D I D I E D U

Next, number the letters of the keyword in the order that they appear in the alphabet. A is 1, E is 2... and so on:

    4 5 3 7 1 6 2 
    P R I V A T E

Then re-arrange each column of letters so that they fall in numerical order:

    1 2 3 4 5 6 7
    A E I P R T V

    M A E F E E D
    I E I N D V L
    M A V G I E E
    K N I D R A N
    E U D D I D I

The ciphertext in this case can be arranged however you want, and whoever knows the keyword can reverse the process and decipher it fairly easily:

MAEFE EDIE INDVL MAV GIE EKNI DRANE UD DIDI

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