The spacing is not related to spaces in the plaintext and so does not carry any information about the plaintext.) This is a common technique used to make the cipher more easily readable. (The cipher has broken this ciphertext up into blocks of five to help avoid errors. For example, using three "rails" and a message of 'WE ARE DISCOVERED FLEE AT ONCE', the cipherer writes out: In the rail fence cipher, the plaintext is written downwards and diagonally on successive "rails" of an imaginary fence, then moving up when we get to the bottom. The Rail Fence cipher is a form of transposition cipher that gets its name from the way in which it is encoded.
RAIL FENCE CIPHER MANUAL
In their book on codebreaking historical ciphers, Elonka Dunin and Klaus Schmeh describe double columnar transposition (see below) as "one of the best manual ciphers known". However, given the right conditions - long messages (e.g., over 100–200 letters), unpredictable contents, unique keys per message, strong transposition methods, and so on - guessing the right words could be computationally impossible without further information. Transposition ciphers have several vulnerabilities (see the section on "Detection and cryptanalysis" below), and small mistakes in the encipherment process can render the entire ciphertext meaningless. In practice, a message this short and with a predictable keyword would be broken almost immediately with cryptanalysis techniques. #1 TWD, #2 IP, #3 SI, #4 HII, #5 IKA, #6 SEĬiphertext in groups of 5 for readability: By contrast, someone with the key could reconstruct the message easily:ġ 4 5 3 2 6 Sequence (key letters in alphabetical order) To decipher the encrypted message without the key, an attacker could try to guess possible words and phrases like DIATHESIS, DISSIPATE, WIDTH, etc., but it would take them some time to reconstruct the plaintext because there are many combinations of letters and words. The resulting message is hard to decipher without the key because there are many ways the characters can be arranged.įor example, the plaintext "THIS IS WIKIPEDIA" could be encrypted to "TWDIP SIHII IKASE". Plaintexts can be rearranged into a ciphertext using a key, scrambling the order of characters like the shuffled pieces of a jigsaw puzzle. Despite the difference between transposition and substitution operations, they are often combined, as in historical ciphers like the ADFGVX cipher or complex high-quality encryption methods like the modern Advanced Encryption Standard (AES). They differ from substitution ciphers, which do not change the position of units of plaintext but instead change the units themselves. Transposition ciphers reorder units of plaintext (typically characters or groups of characters) according to a regular system to produce a ciphertext which is a permutation of the plaintext.
In cryptography, a transposition cipher is a method of encryption which scrambles the positions of characters ( transposition) without changing the characters themselves. JSTOR ( July 2008) ( Learn how and when to remove this template message).Unsourced material may be challenged and removed.įind sources: "Transposition cipher" – news Please help improve this article by adding citations to reliable sources. This article needs additional citations for verification.
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