K4 Solution

The plaintext

Below is the complete K4 plaintext in two forms: a lineated reading version and the continuous cipher-output string. Both represent the same 97 characters. Artist-confirmed anchors (EAST, NORTHEAST, BERLIN, CLOCK) appear at their documented positions. All other characters are produced by the same closed mechanism.

Inscription layout (for reading)

THE COMPASS ROSE IS HERE X
EAST NORTHEAST
THIS IS YOUR POSITION X
COMMISSION
BERLIN CLOCK
WHICH IS NORTHEAST OF HERE X

Continuous string (fidelity reference)

THECOMPASSROSEISHEREXEASTNORTHEASTTHISISYOURPOSITIONXCOMMISSIONBERLINCLOCKWHICHISNORTHEASTOFHEREX

Line breaks in the inscription layout are editorial — they aid readability. The continuous string is the fidelity reference. X functions as a separator/null marker, consistent with Kryptos conventions.

Word-by-word position map

Every word in the plaintext maps to specific positions in the 97-character stream. The table below shows each phrase, its position range, the corresponding ciphertext, and its location on the 7×14 grid.

✓ = artist-confirmed anchor. Tier = row in the 7×14 grid (each tier spans 14 positions).

What the plaintext says

The K4 plaintext reads as a set of navigational instructions anchored to the Kryptos installation itself. Each phrase carries specific physical meaning:

THE COMPASS ROSE IS HERE — The sculpture's compass rose, carved into the courtyard ground, marks the reference point. "Here" is literal: the physical location where you stand.

EAST NORTHEAST — A directional bearing from that reference point. East-northeast (approximately 67.5° from north) establishes the orientation the message is pointing toward.

THIS IS YOUR POSITION — The viewer's location matters. Position is not metaphorical — it is the central variable of the entire cipher mechanism. Every shift value in the 7×14 grid is determined by your position in the stream.

COMMISSION — Likely references the CIA commission that produced Kryptos, or the act of commissioning a message to be sent. Sanborn has stated Kryptos is fundamentally about "delivering a message."

BERLIN CLOCK — References a clock in Berlin. Sanborn confirmed "BERLINCLOCK" at positions 64–74 and in November 2025 clarified that the intended referent is the Weltzeituhr (World Clock) at Alexanderplatz — a world time clock that sits on a compass-rose mosaic — not the Mengenlehreuhr (Set Theory Clock) as the community had assumed for 11 years.

WHICH IS NORTHEAST OF HERE — Berlin is geographically northeast of CIA headquarters in Langley, Virginia, at a bearing of approximately 44° from north. The message confirms the directional relationship between the sculpture and its Berlin referent.

Sanborn has stated that K4's plaintext is itself "a riddle" that will "lead to something else" — a reference to the announced K5, a new 97-character coded message thematically connected to K2.

The four confirmed anchors

Jim Sanborn publicly confirmed four K4 plaintext segments over a span of ten years. All four are preserved at their exact documented positions in this solution.

The combined known plaintext at positions 22–34 reads EASTNORTHEAST. At positions 64–74 it reads BERLINCLOCK. Both fragments align with the navigational instruction reading of the full plaintext.

How the cipher works (simplified)

K4 is a double-keyed Vigenère cipher. The KRYPTOS tableau on the sculpture is the cipher machine. Two keys — a row key f and a column key g — tell you how to enter the tableau. For each of the 97 positions:

r = ( f(C) + g(T) ) mod 26
R = r + gate
P = ( stdpos(C) − R ) mod 26

C is the ciphertext letter (A=0, B=1, … Z=25). T is the helper letter read from the active tableau row. f(C) selects which tableau row to enter. g(T) selects which column to read. Their sum gives r, the base shift. The gate is a position-derived binary value: 1 or 0, determined by the 31-column packet phase, tier mod 3 carrier cycle, and seam-corner override. The final subtraction produces the plaintext letter P.

The f values come from the compass bearings and misspelling clues. The g values come from the tableau’s helper rows (X, Y, Z) and a 3×3 control card. The gate is a physical geometric property of the sculpture’s S-curve. See the Field Guide for the complete on-site derivation.

Worked example: Positions 1–5

Here are the first five positions of K4, computed step by step:

Reading the plaintext column: T, H, E, C, O — the first five letters of "THECOMPASS..." Every position in the cipher resolves the same way. The full 97-position reconciliation table is available on the verification page.

The 7×14 shift grid

The 97 characters of K4 map to a grid of 7 tiers (rows) and 14 lanes (columns) — a total of 98 cells, with one blank at Tier 7, Lane 13. Each cell holds an R value (the shift applied at that position). The grid coordinates are computed from the stream position:

lane = ((i − 2) mod 14) + 1
tier = ⌈i / 14⌉

For the complete R-grid and r-grid tables, worked examples at every tier, and the binary gate map, see How It Works. For the full 97-row reconciliation table, see Verify It Yourself.

Cipher classification

K4 is a double-keyed Vigenère cipher that uses the KRYPTOS tableau printed on the sculpture as its lookup square. Two keys — a row key f (applied to the ciphertext letter) and a set of column keys g (applied to the helper letter) — disguise entry into the tableau so that it cannot be read directly. The KRYPTOS tableau on the sculpture IS the cipher machine.

The decryption formula: r = (f(C) + g(T)) mod 26, then R = r + gate (gate is position-derived: 1 or 0), then P = (stdpos(C) − R) mod 26. The four passes are X (positions 1–4), Y (5–35), Z1 (36–66), and Z2 (67–97).

A small set of master constants drives the entire system, all derivable from on-site artifacts: 4 (tail multiplier from T clue), 13 (scaffold default), 19 (bridge offset), 3 and 11 (compass seeds), and 24 (seam base). See the Field Guide for the complete derivation.

How every clue maps to a solve step

Sanborn’s clues are not decoration. Every one performs a specific function in the on-site decryption procedure:

What remains

The cipher mechanism is fully closed. The plaintext, the f/g decomposition, the binary gate, and all master constants are known and verified at 97/97 positions. The formula r = (f(C) + g(T)) mod 26 derives every base shift from the ciphertext letter, the helper letter, and on-site clues. No external chart, no hidden key, no second layer is required.

What remains is artist confirmation of the complete encryption method. Sanborn has confirmed four plaintext anchors but has not publicly released the coding procedure. The mechanism documented here is independently derived and awaits formal confirmation from the artist or from the sealed Smithsonian records (embargoed until 2075).

Sanborn has announced K5 — a new 97-character coded message to be released publicly when K4 is cryptographically solved.

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Frequently asked questions

What is the K4 plaintext?

THE COMPASS ROSE IS HERE X EAST NORTHEAST THIS IS YOUR POSITION X COMMISSION BERLIN CLOCK WHICH IS NORTHEAST OF HERE X — a 97-character navigational instruction anchored to the Kryptos courtyard installation, pointing toward the Berlin Clock (Weltzeituhr at Alexanderplatz).

How was K4 solved?

Through structural cryptanalysis working outward from the four artist-confirmed anchors (EAST, NORTHEAST, BERLIN, CLOCK). The anchors provided known plaintext at fixed positions, which constrained the R-values at those positions. Extending those constraints across the full 97-position stream — using the 7×14 grid geometry and binary gate — produced a complete, self-consistent plaintext.

Is K4 officially confirmed?

The four anchor words are confirmed by the artist. The full 97-character plaintext was independently recovered from Sanborn's Smithsonian archives in September 2025 by Jarett Kobek and Richard Byrne and was not publically disclosed. In December of 2025, the plaintext solution was independently derived by the author of this site. Sanborn has not publicly released the full text or the encryption method.

What does the K4 plaintext mean?

It reads as a site-specific navigational instruction: the compass rose at CIA headquarters is the reference point; east-northeast is the bearing; Berlin (specifically the Weltzeituhr at Alexanderplatz) is the destination. Sanborn has stated the plaintext is itself "a riddle" leading to K5, a new coded message connected to K2.

What is the Berlin Clock reference?

Sanborn confirmed "BERLINCLOCK" at positions 64–74. For 11 years the community assumed this meant the Mengenlehreuhr (Set Theory Clock). In November 2025, Sanborn clarified the intended referent is the Weltzeituhr (World Clock) at Alexanderplatz — a world time display that sits on a compass-rose mosaic, mirroring Kryptos's own compass rose.

What would falsify this solution?

Confirmation of any plaintext letter inconsistent with the full 97-character string at its verified position, or release of Sanborn's original coding records showing R-values or r-values that contradict the published reconciliation table. The mechanism is falsifiable by design: every claim is position-indexed and arithmetically checkable.

What does OBKR mean in Kryptos?

OBKR are the first four ciphertext characters of K4. They occupy the capstone alignment row — the rightmost four columns of the last row shared with K1–K3 on the copper screen. Under the proposed solution, OBKR decrypts to THEC (the start of "THE COMPASS ROSE IS HERE"). The letters themselves are not an acronym; they are the encrypted form of the plaintext at positions 1–4.

Who solved Kryptos K4?

The K4 plaintext was independently recovered from Jim Sanborn's Smithsonian archives in September 2025 by journalist Jarett Kobek and artist Richard Byrne — though they emphasized this was not a cryptographic solution. The complete cryptographic mechanism (R-grid, r-grid, binary gate, and shift tables) was independently derived and documented by Matt Lacy in December 2025. K1–K3 were solved by CIA analyst David Stein (1998, classified) and cryptographer Jim Gillogly (1999, public).