The Decoding Room

In their secret headquarters deep underground, scientists work day and night to decipher The Enemy's intercepted signals. See how YOU would make out!

Codes and Ciphers


Codes and ciphers are both ways of sending secret messages. In code, words or phrases are assigned different meanings known only to the recipient of the message; e.g. 'Three pints of milk Saturday please' could stand for 'You will assassinate the Queen at midnight on Sunday.'
In cipher, the letters of a message are altered in a way known only to the writer of the message and its recipient. For example, the letters may be:

Moved a number of places forwards or backwards in the alphabet
Npwfe b ovncfs pg qmbdft gpsxbset ps cbdlxbset jo uif bmnibcfu

Or rearranged
A danger error

Or written backwards
Sdrawkcab nettirw ro

Or replaced by numbers
15/18 18/5/16/12/1/3/5/4 2/25 14/21/13/2/5/18/19

Anything written in cipher is called a cryptogram, and the method of putting a message into cipher is called encryption.

Try to unscramble these examples, all of which are useful phrases for an espionage agent in the field. If you get really stuck, the answers are at the bottom. All are based on the methods above except the last one.

Edanerg taht ni kcab nip taht tup ot uoy redro i.

Hr sgzs z ftm hm xntq onbjds nq zqd xnt itrs okdzrdc sn rdd ld?

8/1/14/4/19 21/16, 25/15/21 3/1/4!

Hist tegrota si orf ym won ronalpes seu, Rm Smutsoc Fercifo.

697 q43h[5 43qoo6 t98ht 59 5y492 j3 59 5y9w3 d49d9e8o3wk q43 697:
(Hint: what happens if you type without looking at the keyboard?)

Polybius' Code

And now, some history. A cipher used by the Ancient Romans.

           COLUMNS

         1  2  3  4  5

  R   1  A  B  C  D  E

  O   2  F  G  H  I  J

  W   3  K  L  M  N  O

  S   4  P  Q  R  S  T

      5  U  V  W  XY Z
A letter is written down as a two-figure number with the row given first and the column second, e.g.
Oh, hi, Brutus! ARGH!
35/23, 23/24, 12/43/51/45/51/44! 11/43/22/23!

Well, that's not bad for a bunch of orgy-crazed sheet-wearing murderers, but we of the computing age can go one better. Simply write a secret message in the space below and click on ENCRYPT to see it transformed into cipher! As you will see, it is a simple letter-substitution cipher with the letters moved 13 places forwards.

And those answers:
1. I order you to put that pin back in that grenade. (written backwards)
2. Is that a gun in your pocket or are you just pleased to see me? (letters 1 place back)
3. Hands up, you cad! (letters replaced by equivalent numbers)
4. This garotte is for my own personal use, Mr Customs Officer. (letters rearranged)
5. You aren't really going to throw me to those crocodiles, are you? (typed one row up)