This document outlines some of the major themes that are present in the Kryptos sculpture. The hope is that this document will make it easier to look for clues to solving K4, because it will help potential solvers to make connections between the many pieces of information that have been revealed thus far. It might also help potential solvers to get into the mindset that Sanborn approached the puzzle with. The themes that I explore are:

• Light and Darkness
• Invisible Forces
• Coordinates, Directions, Locations
• Information, and Intelligence Gathering
• Ancient Structures
• Layers
• Detecting and Revealing Hidden Things

Light and Darkness

Kryptos includes both direct and indirect references to light. Visible light is a portion of the electromagnetic spectrum. The examples below include references not just to visible light but to the rest of the electromagnetic spectrum as well.

• Light is an element not only of this sculpture but of related Sanborn sculptures as well, such as Antipodes and the Cyrillic Projector.
• K1 talks about subtle shading (which I take to mean gradients of light), as well as the absence of light (shadow, or darkness).
• K2 makes reference to something that is totally invisible. In other words, it is hidden because any electromagnetic energy that it might be giving off can't be detected.
• K3 mentions light in various places. There is the candle, and the flame that flickers, and the illumination of the chamber, which makes the details visible. At the end, the question is asked "can you see anything?"
• The Berlin hint could be thought of as having a theme of light, because the light on one side of the wall could not reach the other until after the wall came down.
• Parts of the Kryptos installation feature morse code, which uses dots and dashes to encode information. This is reminiscent of binary systems, which use ones and zeroes, which could be thought of as on/off or light and dark.

Invisible Forces

Another theme of Kryptos is that of invisible forces. There are references to magnetic fields, information transmission using electromagnetic energy, and so on. Invisible forces are also present in other Sanborn works. Sanborn's artworks have dealt with (among other things) radiation, magnetic fields, and hidden flows, to name a few.

• K2 refers to something that was hidden by making use of the Earth's magentic field. An example of something that can be detected with the Earth's magnetic field is a submarine. The size and shape of a submarine makes it susceptible to detection because it creates a magnetic anomaly that differs from the Earth's magnetic field. Even when submarines are constructed with non-ferromagnetic materials, they still create enough of an anomaly to be detected via magnetic anomaly detection techniques.
• K2 sounds like it could refer to geocaching, which is the hobby of burying or hiding something and then publishing the geospatial coordinates for that object (or publishing clues and hints that reveal those coordinates) so that others can find the cache. Geocaching makes uses of GPS technology, which works by sending and receiving signals from orbiting satellites. These signals, and the satellites as well, are propelled by invisible forces.
• K2 says the message was transmitted underground. "Transmission" often refers to radio transmissions. Radio waves could be thought of as an invisible force.
• Part of the sculpture is a lodestone. A compass rose is on one of the stones near the sculpture. A lodestone is a naturally formed stone that has a strong magnetic field, which exerts invisible forces.
• The pool of water at the base of the Kryptos copper plates has a pump that causes the pool to swirl continually. This is meant to symbolize an invisible force.
• Morse code is incorporated into parts of the sculpture. Morse code was transmitted over wires, and it was sometimes powered by telluric currents, which are electrical currents that move through the ground. This is another example of an invisible force.

Coordinates, Directions, Locations

Kryptos also has a theme of coordinates, directions, and locations. Such things are referenced throughout the plaintext, as well as in some of the other elements of the sculpture.

• A compass rose in a stone of the sculpture points to a lodestone nearby.
• K2 mentions geospatial coordinates.
• The abscissa keyword is a word that means the first of a coordinate pair.
• K1 talks of illusion as existing in the space between shading and darkness. In a sense, by saying that illusion is between something, it is specifying the location of illusion.
• K2 talks about an unknown location that is out there somewhere.
• K2 mentions "layer two," which could be a reference to something being located at a second layer.
• K3 is about Tut's tomb, which Howard Carter had to locate by examining historical information.
• K3 mentions the upper left hand corner of a wall, and mentions the lower part of the doorway. These are both locations that are described with spatial terminology.
• William Webster said that the sculpture "speaks to a sense of place."
• Some of the morse code on other parts of the sculpture says "t is your location." The morse code might be partially obscured by rock, and it might say "What is your location?"
• The copper sheets are divided into four sections. These resemble quadrants of a coordinate system.
• The Vigenère encryption system uses tableaus like the ones on the right side of the Kryptos copper plate. Sanborn has likened it to a mileage map. The process of finding the plaintext letter that a ciphertext letter represents in this type of system is somewhat like finding the location that a set of coordinates points to.

Information, and Intelligence Gathering

It has been said that the theme of Kryptos is "intelligence gathering." The theme of information and intelligence gathering is evident throughout the entire Kryptos installation.

• K1 refers to illusion. Illusion is the obfuscation of information. K1 says that illusion comes from a careful combination of shading (light) and darkness. Taken more literally, this can mean that information can be altered in someone's perception, or even hidden in plain sight by carefully controlling what can be seen or can't be seen. Furthermore, information can be found not only by looking at what is there, but also by looking at what is not there.
• K2 specifically mentions information. This information is described as having been gathered and transmitted underground to an unknown location. It is unclear whether the information mentioned here is the thing that has allegedly been buried.
• Another piece of information mentioned in K2 is "his last message." WW, or William Webster, is mentioned before that, and some coordinates and "layer two" are mentioned afterward, but it is unclear as to whether the coordinates are the last message, and whether the "his" refers to William Webster or not.
• K3 also deals with information. Carter had to gather a great deal of information in order to narrow down the location of Tut's tomb. And then when he opened the chamber, the information contained therein was illuminated with the light from his candle.
• The morse code in other parts of the sculpture is a form of information that has, in a way, been concealed because it is encoded.

Ancient Structures

Kryptos refers to ancient structures, including the petrified wood in parts of the sculpture, and Tut's tomb, among others.

• Tut's tomb is an ancient structure that Kryptos refers to. The tomb had been lost to history for a long time, but it was rediscovered after some intelligence gathering.
• Sanborn has said that Kryptos is meant to look like it had already been there and that the CIA Headquarters had been built around it.
• The petrified wood is an ancient structure that has been changed over time into something different.
• Kryptos had been planned to be a cylinder around a petrified piece of wood, which could be symbolic of Tut's tomb and other ancient structures.
• In general, an ancient structure is something that becomes hidden over time and is only discovered later through physical anomalies or historical clues.
• Sanborn said in a quote that K4 is like grains of sand in an hourglass, and as more layers of the onion are unraveled, the smaller the grain of sand will be that is needed to crack the ciphertext. This sounds similar to the process that is needed in order to find an ancient structure.

Layers

The theme of layers appears in various aspects of the sculpture.

• The palimpsest keyword is a reference to layers. A palimpsest is a piece of paper or other surface that had information on it, but that information was obscured or erased in order to put new information on top of it. Some documents of this nature have been analyzed, and the original information has been extracted.
• Various physical elements of the sculpture include layers. There are layers of rock and metal.
• K2 specifically mentions "layer two." This layer was not visible until Sanborn revealed his mistake (or, maybe, "mistake.")
• K1 could be interpreted as saying that illusion exists between a layer of light and a layer of darkness.
• K2 mentions that something is buried underground, or in other words, under a layer of ground.
• Many layers concealed Tut's tomb. There were physical layers, like earth, walls, and debris. There were information layers, where history and time obscured the information about the location of the tomb.
• The ciphertext is information that is effectively hidden under a layer of encryption.

Detecting and Revealing Hidden Things

The sculpture's name, Kryptos, means hidden. The theme of something hidden being revealed is everywhere in the sculpture. Kryptos is related to the word "crypt," which is a closed room.

• K1 refers to something hidden when it mentions illusion. Illusion can be used to hide something in plain sight.
• K2 mentions an unknown location, something buried, information that was transmitted underground. These are all references to hiding things.
• K3 speaks of Tut's tomb, which was hidden for many years.
• Morse code and other encoding schemes are ways of hiding information.
• Tut's tomb was opened, revealing the information inside.
• The abscissa keyword is related to words meaning "to cut away," which is reminiscent of the cutting away of the wall in Tut's tomb.
• The Berlin hint makes us think of the Berlin wall, in that the wall was cut away to reveal things that were hidden.
• Some elements of the sculpture are partly obscured under ground or rocks.