KRYPTOS, that peculiar sculpture in the courtyard area of the headquarters complex, has raised many eyebrows and questions ever since its installa-tion. Undoubtedly its most intriguing aspect is the riddle of its hidden message. What could it be? Though few persons other than the author know the answer for certain, many have contemplated the question. We would like to pass on what knowledge we have gained from our cryptanalysis regarding the message.

It is probable, from analysis of the letter distribution, that at least four separate systems of encryption have been employed: Digraphic, Poly-alphabetic,Transposition, and One-Time-Pad.

The first of these, Digraphic substitution, is guessed to be applicable from "EMUFPH..." to "... GWHKK?". Thus method substitutes two letters for one letter, or even a whole syllable or word (e.g., JK=g, or FE=ible).

The Polyalphabetic system appears to be used with the text extending from approximately "DQMCPF..." up to "...JLLAETG". In this system, multiple alphabets (we suspect four or eight) are used to substitute different letters for the same letters in the origina l text. For example, an "F" may be translated into an "R" one time, and then as an "M" another time, and as a "D" a third time.

"ENDYAHR..." through "TVDOHW?" is guessed to incorporate a transposition system, also known as a permutation. This is a system in which the letters in the original message are mixed up according to a predefined rule. Often, the message is arranged into a matrix, say, reading left to right; then, the message is output reading down the colunms. (See example next page.) Perhaps a matrix system in which the length of the columns are multiples of eleven or thirteen has been used for this section of the message.

 |-------------------------------------|
 |       The KRYPTOS Inscription       |
 |                                     |
 |  EMUFPHZLRFAXYUSDJKZLDKRNSHGNFIVJ   |
 |  YQTQUXQBQVYUVLLTREVJYQTMKYRDMFD    |
 |  VFPJUDEEHZWETZYVGWHKKQETGFQJNCE    |
 |  GGWHKK?DQMCPFQZDQMMIAGPFXHQRLG     |
 |  TIMVMZJANQLVKQEDAGDVFRPJUNGEUNA    |
 |  QZGZLECGYUXUEENJTBJLBQCRTBJDFHRR   |
 |  YIZETKZEMVDUFKSJHKFWHKUWQLSZFTI    |
 |  HHDDDUVH?DWKBFUFPWNTDFIYCUQZERE    |
 |  EVLDKFEZMOQQJLTTUGSYQPFEUNLAVIDX   |
 |  FLGGTEZ?FKZBSFDQVGOGIPUFXHHDRKF    |
 |  FHQNTGPUAECNUVPDJMQCLQUMUNEDFQ     |
 |  ELZZVRRGKFFVOEEXBDMVPNFQXEZLGRE    |
 |  DNQFMPNZGLFLPMRJQYALMGNUVPDXVKP    |
 |  DQUMEBEDMHDAFMJGZNUPLGEWJLLAETG    |
 |  ENDYAHROHNLSRHEOCPTEOIBIDYSHNAIA   |
 |  CHTNREYULDSLLSLLNOHSNOSMRWXMNE     |
 |  TPRNGATIHNRARPESLNNELEBLPIIACAE    |
 |  WMTWNDITEENRAHCTENEUDRETNHAEOE     |
 |  TFOLSEDTIWENHAEIOYTEYQHEENCTAYCR   |
 |  EIFTBRSPAMHHEWENATAMATEGYEERLB     |
 |  TEEFOASFIOTUETUAEOTOARMAEERTNRTI   |
 |  BSEDDNIAAHTTMSTEWPIEROAGRIEWFEB    |
 |  AECTDDHILCEIHSITEGOEAOSDDRYDLORIT  |
 |  RKLMLEHAGTDHARDPNEOHMGFMFEUHE      |
 |  ECDMRIPFEIMEHNLSSTTRTVDOHW?OBKR    |
 |  UOXOGHULBSOLIFBBWFLRVQQPRNGKSSO    |
 |  TWTQSJQSSEKZZWATJKLUDIAWINFBNYP    |
 |  VTTMZFPKWGDKZXTJCDIGKUHUAUEKCAR    |
 |-------------------------------------|

|------------------------------------------------------------|
|            Example of a Columnar Transposition             |
|                                                            |
| Original message: "Cryptography is a useful tool for       |
| information protection"                                    |
|                                                            |
| 7x7 Matrix:  C R Y P T O G                                 |
|              R A P H Y I S                                 |
|              A U S E F U L                                 |
|              T O O L F O R                                 |
|              I N F O R M A                                 |
|              T I O N P R O                                 |
|              T E C T I O N                                 |
|                                                            |
| Encrypted message: "CRATI TTRAU ONIEY                      |
|       PSOPO CPHEL ONTTY FFRPI OIUOM                        |
|       ROGSL RAONX"                                         |
| (made by reading down the columns, then breaking           |
| into 5-letter blocks.  The last "X" is an arbitrary        |
| filler so the last group will also have 5 letters.)        |
|                                                            |
|------------------------------------------------------------|

Finally, the part of the message from "OBKRUO..." to the end may make use of a one- time system. Essentially, every character in the original message is encrypted using its own unique alpha- bet. This is a very secure cryptographic system, because if the alphabets used are selected at random, there is no pattern to follow for anyone trying to break the code.

The other half of the sculpture may provide a clue as to which alphabets are used, however. It is an arrangement of the alphabet, known as a Vigenere Square, in which each successive row is shifted one place to the left (In this case, some of the letters are shifted in position to spell the word KRYPTOS), with reference alphabets along the top, bottom, and side. Though used in many ways, this table is very often used for one-time-pad encryption. For example, if someone wanted to encrypt the letter "G", and the key they were using was the letter "F", he would just look down column "G" to row "F" and would see that "G" becomes an,'E'. Since there are 26 rows and column on the Vigenere square, any letter can be encrypted as any other letter depending on the key used.

There is speculation that the other elements of Jim Sanborn's sculpture may hold clues to the cipher used in the message in the courtyard, but there is yet no proof. You may have noted the dots and dashes on the metal sheets between the granite slabs in front of the NHB (New Headquarters Building?) entrance; this is Morse Code, and there are five phrases: "DIGE TAL INTERPRETATU", "T IS YOUR POSITION", "VIRTUALLY INVISIBLE", "SHADOW FORCES", and "LUCID MEMORY". Also to be found are the letter combinations "SOS" and "RQ".

In the case of the sculpture, cryptography is mainly an intriguing oddity; but cryptography has a very real role in the world of intelligence. (Information and sources need to be protected, and cryptography can afford that protection.)

If you decide to tackle the cipher, good luck! We will attempt to keep you posted on any relevant developments as they arise.