Scytale - Wikipedia, the free encyclopedia


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Scytale

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This article is about the encryption device; for the Dune character,
see Scytale (Dune).




A scytale
In cryptography, a
scytale (rhymes with Italy, and also transliterated as skytale,
Greek σκÏÏ"ÎŹÎη, a baton) is a tool used to perform a transposition
cipher, consisting of a cylinder with a
strip of leather wound around it on which is written a message. The ancient Greeks, and the
Spartans in
particular, are said to have used this cipher to communicate during military
campaigns.
The recipient uses a rod of the same diameter on which he wraps the
paper to read the message. It has the advantage of being fast and not prone to
mistakes â€" a necessary property when on the battlefield. It can, however, be
easily broken. Since the strip of
paper hints strongly at the method, the ciphertext would have to be
transferred to something less suggestive, somewhat reducing the advantage
noted.





Contents

1 Encrypting
2 Decrypting
3 History
4 References


//

[edit]
Encrypting
Suppose the rod allows one to write 4 letters around it in one circle and 5
letters down the side. Clear text: "Help me I am under attack" To encrypt one
simply writes across the leather..._____________________________________________________________
| | | | | | |
| | H | E | L | P | M |
|__| E | I | A | M | U |__
| N | D | E | R | A | |
| T | T | A | C | K | |
| | | | | | |
_____________________________________________________________

so the cipher text becomes, "HENTEIDTLAEAPMRCMUAK" after unwinding.

[edit]
Decrypting
To decrypt all one must do is wrap the leather strip around the rod and read
across. ciphertext: "HENTEIDTLAEAPMRCMUAK" Every fourth will appear on the same
line so the cipher text becomesHELPM...return to the beginning once the end is reached
...EIAMUNDERATTACK.

Insert spaces and the plain text returns, "Help me I am under attack"

[edit]
History
From indirect evidence, the scytale was first mentioned by the Greek poet Archilochus who lived in the
7th century BC. Other Greek and Roman writers during the following centuries
also mentioned it, but it was not until Apollonius of
Rhodes (middle of the 3rd century BC) that a clear indication of its use as
a cryptographic device appeared. A description of how it operated is not known
from before Plutarch (50-120 AD):

The dispatch-scroll is of the following character. When the ephors send
out an admiral or a general, they make two round pieces of wood exactly alike
in length and thickness, so that each corresponds to the other in its
dimensions, and keep one themselves, while they give the other to their envoy.
These pieces of wood they call scytalae. Whenever, then, they wish to send
some secret and important message, they make a scroll of parchment long and
narrow, like a leathern strap, and wind it round their scytale, leaving no
vacant space thereon, but covering its surface all round with the parchment.
After doing this, they write what they wish on the parchment, just as it lies
wrapped about the scytale; and when they have written their message, they take
the parchment off and send it, without the piece of wood, to the commander.
He, when he has received it, cannot otherwise get any meaning out of
it,--since the letters have no connection, but are disarranged,--unless he
takes his own scytale and winds the strip of parchment about it, so that, when
its spiral course is restored perfectly, and that which follows is joined to
that which precedes, he reads around the staff, and so discovers the
continuity of the message. And the parchment, like the staff, is called
scytale, as the thing measured bears the name of the
measure.â€"Plutarch, Lives (Lysander 19), ed. Bernadotte
Perrin.
Due to difficulties in reconciling the description of Plutarch with the earlier
accounts, and circumstantial evidence such as the cryptographic weakness of the
device, several authors have suggested that the scytale was used for conveying
messages in plaintext, and that Plutarch's
description is mythological.

[edit]
References

Thomas Kelly, The myth of the skytale, Cryptologia, July 1998, pp.
244–260.
Secret
Language in Graeco-Roman antiquity. Thesis by Brigitte Collard that
includes quotations of many ancient references to the scytale. (In French)





Classical cryptography

v â€Ã³ d
â€Ã³ e

Ciphers: ADFGVX | Affine | Alberti | Atbash | Autokey | Bifid | Book | Caesar | Four-square |
Hill | Keyword | Nihilist | Permutation |
Pigpen | Playfair | Polyalphabetic
| Polybius | Rail Fence | Reihenschieber | Reservehandverfahren
| ROT13 | Running key |
Scytale | Smithy code | Solitaire | Straddling
checkerboard | Substitution |
Tap
Code | Transposition
| Trifid | Two-square | VIC
cipher | Vigenère

Cryptanalysis: Frequency
analysis | Index of
coincidence

Misc: Cryptogram | Bacon | Polybius square |
Scytale | Straddling
checkerboard | Tabula recta


Cipher machines
v â€Ã³ d
â€Ã³ e

Rotor machines:
CCM | Enigma | Fialka | Hebern | HX-63 | KL-7 | Lacida | M-325 | Mercury |
NEMA | OMI | Portex | SIGABA | SIGCUM | Singlet | Typex

Mechanical: Bazeries
cylinder | C-36 | C-52 | CD-57 | Cipher
disk | HC-9
| Kryha | Jefferson disk | M-94 | M-209 | Reihenschieber |
Scytale

Teleprinter: 5-UCO | BID 770 | KW-26 | KW-37 | Lorenz SZ 40/42 |
Siemens and
Halske T52

Secure voice: KY-3 | KY-57 | KY-58 | KY-68 | OMNI | SIGSALY | STE | STU-II | STU-III | VINSON | SCIP | Sectéra Secure
Module

Miscellaneous: Cryptex | JADE | KG-84 | KL-43 | Noreen | PURPLE | Pinwheel |
Rockex


Cryptography
v â€Ã³ d â€Ã³ e

History of
cryptography | Cryptanalysis | Cryptography
portal | Topics in
cryptography

Symmetric-key
algorithm | Block cipher | Stream cipher | Public-key
cryptography | Cryptographic
hash function | Message
authentication code | Random
numbers
Retrieved from "http://en.wikipedia.org/wiki/Scytale"

Categories: Classical
ciphers | Encryption
devices



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