This is the second in a series of Unsolved Mysteries posts. These posts explore current unsolved real-world puzzles. Since these have been unsolved for years, it's uncertain whether anyone on on Puzzling.SE will be able to find a solution, but we do have a lot of brilliant minds here...
Related meta post: Posting famous unsolved puzzles
In 1988, as a new headquarters for the American Central Intelligence Agency (CIA) was being built in Langley, Virgina, sculptor Jim Sanborn was commissioned to create artwork for the courtyard of the new building. He designed a large copper monument, shaped somewhat like a flag, and engraved with hundreds of letters -- an encrypted message:
A soon as the sculpture was revealed, codebreakers both at the CIA and in the general public went to work on the puzzle. In 1999, a computer scientist named Jim Gillogly announced that he had solved most of the puzzle. There were four distinct parts to the code, and he had managed to solve the first three.
After his announcement, the CIA revealed that they had actually solved the first three parts internally, the year before. (Later, the U.S. National Security Administration (NSA) also claimed to have solved the first three parts in 1992.)
The fourth section of the code remained unsolved, and to date, no one has brought forth a credible solution for part 4.
The "tableau" on the sculpture has two sections. One side has the encrypted text, and the other is an alphabet table of sorts. (image credit: kryptosrevisited.com)
(a plaintext version of the tableaux is available here -- just scroll down)
Other components of Kryptos
In addition to the copper sculpture pictured above, the artist created various other visual elements that are part of the same installation. There is a pool at the base of the sculpture, and a bench. There are also various large slabs of stone strewn about the area with various Morse Code messages. It is unclear whether these messages are related to the solving of the Kryptos cipher or whether they are simply adding to the artistic aspect of the sculpture. The Morse messages are as follows (some run right into the ground, so the text in brackets is a guess):
SOS LUCID MEMORY [WHA]T IS YOUR POSITION SHADOW FORCES VIRTUALLY INVISIBLE DIGETAL INTERPRETAT[ION] RQ
Solving the first 3 parts
Note: This section contains spoilers regarding the first three sections of the Kryptos code. If you want to try to solve these yourself, do not read this section. These are provided here to help set the context for the fourth (unsolved) section of the code.
Though it was only discovered by solving Part 1, the ciphertext for Part 1 comprises the first two lines of the encrypted text:
It was encrypted using a Vigenere cipher, with a key of
PALIMPSEST and the modified alphabet depicted on the second tableau.
(A palimpsest is a document (often vellum, but possibly parchment or paper), which has had its original text erased and has then been written over with new text.)
To decrypt the text, we reverse the process that was used to encrypt it. First, write out the keyword repeatedly underneath the ciphertext:
Then use the Kryptos alphabet tableau to look up the decryption for each letter (note that we ignore the top row and left column as depicted in the tableau above):
KRYPTOSABCDEFGHIJLMNQUVWXZKRYP RYPTOSABCDEFGHIJLMNQUVWXZKRYPT YPTOSABCDEFGHIJLMNQUVWXZKRYPTO PTOSABCDEFGHIJLMNQUVWXZKRYPTOS TOSABCDEFGHIJLMNQUVWXZKRYPTOSA OSABCDEFGHIJLMNQUVWXZKRYPTOSAB SABCDEFGHIJLMNQUVWXZKRYPTOSABC ABCDEFGHIJLMNQUVWXZKRYPTOSABCD BCDEFGHIJLMNQUVWXZKRYPTOSABCDE CDEFGHIJLMNQUVWXZKRYPTOSABCDEF DEFGHIJLMNQUVWXZKRYPTOSABCDEFG EFGHIJLMNQUVWXZKRYPTOSABCDEFGH FGHIJLMNQUVWXZKRYPTOSABCDEFGHI GHIJLMNQUVWXZKRYPTOSABCDEFGHIJ HIJLMNQUVWXZKRYPTOSABCDEFGHIJL IJLMNQUVWXZKRYPTOSABCDEFGHIJLM JLMNQUVWXZKRYPTOSABCDEFGHIJLMN LMNQUVWXZKRYPTOSABCDEFGHIJLMNQ MNQUVWXZKRYPTOSABCDEFGHIJLMNQU NQUVWXZKRYPTOSABCDEFGHIJLMNQUV QUVWXZKRYPTOSABCDEFGHIJLMNQUVW UVWXZKRYPTOSABCDEFGHIJLMNQUVWX VWXZKRYPTOSABCDEFGHIJLMNQUVWXZ WXZKRYPTOSABCDEFGHIJLMNQUVWXZK XZKRYPTOSABCDEFGHIJLMNQUVWXZKR ZKRYPTOSABCDEFGHIJLMNQUVWXZKRY
The first letter is
E, and the first letter of the key (
P. So we find
P in the leftmost column, move right until we hit
E, and then move up to the top, ending at
B. This makes the first letter of our plaintext a
| V KRYPTOSABCDEFG... RYPTOSABCDEFGH... YPTOSABCDEFGHI... --> PTOSABCDEFGHIJ... TOSABCDEFGHIJL... OSABCDEFGHIJLM... ...
For the next letter, we find
A in the leftmost column, and follow it to the right until we hit
M, then up, ending at
Continuing on in this way, we end up with the following decryption:
With spaces and proper case:
Between subtle shading and the absence of light lies the nuance of iqlusion
The ciphertext for Part 2 comprises the remaining text in the top half of the tableau (until the break halfway down, i.e. lines 3 to 12):
VFPJUDEEHZWETZYVGWHKKQETGFQJNCE GGWHKK?DQMCPFQZDQMMIAGPFXHQRLG TIMVMZJANQLVKQEDAGDVFRPJUNGEUNA QZGZLECGYUXUEENJTBJLBQCRTBJDFHRR YIZETKZEMVDUFKSJHKFWHKUWQLSZFTI HHDDDUVH?DWKBFUFPWNTDFIYCUQZERE EVLDKFEZMOQQJLTTUGSYQPFEUNLAVIDX FLGGTEZ?FKZBSFDQVGOGIPUFXHHDRKF FHQNTGPUAECNUVPDJMQCLQUMUNEDFQ ELZZVRRGKFFVOEEXBDMVPNFQXEZLGRE DNQFMPNZGLFLPMRJQYALMGNUVPDXVKP DQUMEBEDMHDAFMJGZNUPLGEWJLLAETG
It is solved in exactly the same way as the first part, except that it uses the keyword
ABSCISSA instead of
VFPJUDEEHZWETZYVGWHKKQETGFQJNCEGGWHKK?DQMCPFQZDQMMIAGPFXHQRLGTIMVMZJANQLVKQEDAGDVFRPJUNGEUNAQZGZLECGYUXUEENJTBJLBQCRTBJDFHRRYIZETKZEMVDUFKSJHKFWHKUWQLSZFTIHHDDDUVH?DWKBFUFPWNTDFIYCUQZEREEVLDKFEZMOQQJLTTUGSYQPFEUNLAVIDXFLGGTEZ?FKZBSFDQVGOGIPUFXHHDRKFFHQNTGPUAECNUVPDJMQCLQUMUNEDFQELZZVRRGKFFVOEEXBDMVPNFQXEZLGREDNQFMPNZGLFLPMRJQYALMGNUVPDXVKPDQUMEBEDMHDAFMJGZNUPLGEWJLLAETG ABSCISSAABSCISSAABSCISSAABSCISSAABSCI?SSAABSCISSAABSCISSAABSCISSAABSCISSAABSCISSAABSCISSAABSCISSAABSCISSAABSCISSAABSCISSAABSCISSAABSCISSAABSCISSAABSCISSAABSCISSAAB?SCISSAABSCISSAABSCISSAABSCISSAABSCISSAABSCISSAABSCISSAABSCISS?AABSCISSAABSCISSAABSCISSAABSCISSAABSCISSAABSCISSAABSCISSAABSCISSAABSCISSAABSCISSAABSCISSAABSCISSAABSCISSAABSCISSAABSCISSAABSCISSAABSCISSAABSCISSAA ITWASTOTALLYINVISIBLEHOWSTHATPOSSIBLE?THEYUSEDTHEEARTHSMAGNETICFIELDXTHEINFORMATIONWASGATHEREDANDTRANSMITTEDUNDERGRUUNDTOANUNKNOWNLOCATIONXDOESLANGLEYKNOWABOUTTHIS?THEYSHOULDITSBURIEDOUTTHERESOMEWHEREXWHOKNOWSTHEEXACTLOCATION?ONLYWWTHISWASHISLASTMESSAGEXTHIRTYEIGHTDEGREESFIFTYSEVENMINUTESSIXPOINTFIVESECONDSNORTHSEVENTYSEVENDEGREESEIGHTMINUTESFORTYFOURSECONDSWESTIDBYROWS
With spaces and proper case (punctuation in
grey added by me):
It was totally invisible
's that possible? They used the Earth
's magnetic field
The information was gathered and transmitted undergruund to an unknown location
Does Langley know about this? They should
's buried out there somewhere
Who knows the exact location? Only WW
.This was his last message
Thirty eight degrees fifty seven minutes six point five seconds north
Seventy seven degrees eight minutes forty four seconds west
ID by rows
Some years after this was originally solved, the sculptor Sanborn made it known that there was an error in the ciphertext, where a single character had been omitted (right after the word "west" on the second-last line). He assumed that it would be obvious to a solver, because it would cause the remaining text to decipher into gibberish, but by what seems to be coincidence, the text actually deciphered into the phrase "ID by rows."
It has since been determined (and confirmed) that the correct decryption ends with
XLAYERTWO instead of
The ciphertext for Part 3 comprises the majority of the bottom half of the tableau, up to (but not including) the
? character on the fourth-last line:
ENDYAHROHNLSRHEOCPTEOIBIDYSHNAIA CHTNREYULDSLLSLLNOHSNOSMRWXMNE TPRNGATIHNRARPESLNNELEBLPIIACAE WMTWNDITEENRAHCTENEUDRETNHAEOE TFOLSEDTIWENHAEIOYTEYQHEENCTAYCR EIFTBRSPAMHHEWENATAMATEGYEERLB TEEFOASFIOTUETUAEOTOARMAEERTNRTI BSEDDNIAAHTTMSTEWPIEROAGRIEWFEB AECTDDHILCEIHSITEGOEAOSDDRYDLORIT RKLMLEHAGTDHARDPNEOHMGFMFEUHE ECDMRIPFEIMEHNLSSTTRTVDOHW
This turns out to be a very different kind of encryption. It uses a transposition cipher which doesn't actually change any of the letters, but simply rearranges them. The task is to find the method used for the rearrangement.
There have been many different attempts at explaining the transposition. For this kind of transposition cipher, there are many different but cryptographically equivalent ways of describing and performing the cipher that all produce the same text, and there is no way to know which one the cryptographer had used without looking over his shoulder.
Luckily, photographs of the worksheets Sanborn used while enciphering K3 (pictured here) make it clear that the original transposition method is a double route transposition using two completely-filled rectangles. The rectangles are of different sizes, but the same route paths (in by rows and out by upwards columns) are used each time. This cipher does not use a literal key; the route paths and grid sizes are what make up the keys for the two route transpositions.
To encipher, the plaintext is first written into a 42-letter wide and 8-letter high grid, from left to right starting on the top row (that is, the usual reading order). The intermediate ciphertext is read out from that grid in upwards columns, reading each column upwards from the bottom row, starting with the leftmost column.
The intermediate text is then written into a different grid, 14 letters wide and 24 letters high. As before, it is written in by rows in the usual reading order, and read out by upwards columns to produce the text seen on the sculpture.
Deciphering is the inverse of enciphering. First, write the K3 ciphertext into a 14x24 grid by upwards columns. Note the beginning of the ciphertext (
ENDYAHRO...) reads upwards from the bottom of the first column.
ILNTAYESTATHCW BLHMHEHAROIEEH ISIWNTHONRSLEO OLTETYMFTEHMHD ELAAEOAERIILUV TSGCRIPEEPEKET PDNADESTEWCRFR CLRIUARBAELTMT OUPIEHBLMTIIFT EYTPNNTRRSHRGS HEELEEFEAMDOMS RRNBTWIEOTDLHL SNMECIEYTTTDON LTXLHTRGOHCYEH NHWEADCEEAERNE HCRNREYTAAADPM OAMNNSAAUIBDDI RISLELTMTNESRE HAOSEOCAEDFOAF ANNETFNTUDWAHP YHSPITEATEEEDI DSHRDEENOSIOTR NYOANOHEIBRGGM EDNRWEQWFIGEAD
Read out the intermediate text (
ILNTAYES...) by rows. Then, write the intermediate text into a 42x8 grid by upwards columns. The plaintext will be evident on the rows. Note the first letters of the intermediate text (
ILNTAYES...) read upwards from the bottom of the first column.
SLOWLYDESPARATLYSLOWLYTHEREMAINSOFPASSAGED EBRISTHATENCUMBEREDTHELOWERPARTOFTHEDOORWA YWASREMOVEDWITHTREMBLINGHANDSIMADEATINYBRE ACHINTHEUPPERLEFTHANDCORNERANDTHENWIDENING THEHOLEALITTLEIINSERTEDTHECANDLEANDPEEREDI NTHEHOTAIRESCAPINGFROMTHECHAMBERCAUSEDTHEF LAMETOFLICKERBUTPRESENTLYDETAILSOFTHEROOMW ITHINEMERGEDFROMTHEMISTXCANYOUSEEANYTHINGQ
Sanborn's worksheets also make it clear that this text is exactly 336 letters long, equal to the areas of both rectangles. The question mark is not part of this ciphertext, and it is unclear whether it is the first "letter" of the following Part 4 ciphertext or whether it is simply a delimiter or separator.
With spaces and proper case (punctuation in
grey added by me):
,the remains of the passage debris that encumbered the lower part of the doorway was removed
.With trembling hands
,I made a tiny breach in the upper
,widening the hole a little
,I inserted the candle and peered in
.The hot air escaping from the chamber caused the flame to flicker
,but presently details of the room within emerged from the mist
"Can you see anything
The ciphertext for Part 4 is the remaining 97 (or 98 if the question mark is included) characters on the tableau:
?OBKR UOXOGHULBSOLIFBBWFLRVQQPRNGKSSO TWTQSJQSSEKZZWATJKLUDIAWINFBNYP VTTMZFPKWGDKZXTJCDIGKUHUAUEKCAR
Most Kryptos fans assume that decrypting it will involve some combination of the methods used for the first three sections. To date, no one has been able to solve it.
Will you be the first?
Like all of my Unsolved Mysteries puzzles, I will give a 500 rep bounty to anyone who manages to find a credible solution. Alconja and question_asker have both agreed to match this bounty, so the total bounty is 1500 reputation.