Skip to main content

Home Transposition cipher

Transposition cipher

Transposition cipher definition

A transposition cipher is a method of encryption that rearranges the characters or bits in the plaintext according to a certain system (a pattern or a key), while maintaining their original identity. The rearrangement process is called permutation.

See also: Block cipher, AES encryption, 128-Bit encryption

History of transposition ciphers

Transposition ciphers have been used for thousands of years. They were one of the earliest forms of encryption ever recorded — even ancient Greeks and Romans used transposition ciphers. A famous historical example is the Spartan “scytale” cipher: a strip of parchment was wrapped around a staff, and the message was written down the length of the staff, then unwound and sent. Without a staff of the exact diameter, the message could not be read.

Advantages of using transposition ciphers

  • Transposition ciphers are relatively easy to understand and implement, requiring no complex algorithms.
  • Transposition ciphers can be used in combination with other types of ciphers to create more secure encryption.

Disadvantages of using transposition ciphers

  • On their own, transposition ciphers are quite weak and can be broken with pattern analysis or by guessing the permutations.
  • A single error in encryption or transmission can make a large portion of the message unreadable.