Kryptos K4 Solution

The plaintext

The four anchor words (EAST, NORTHEAST, BERLIN, CLOCK) are artist-confirmed and fixed at their documented positions. The remaining characters are a reconstruction: consistent with the anchors and with plausible English, and used to build the mechanism model, which means the model reproduces them by construction. They are not independently verified, and the authenticated plaintext recovered from the archive is not public. Roughly 24 of 97 positions are confirmed; the rest is reconstruction, shown below in two forms: a lineated reading version and the continuous string.

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. Three independent things Sanborn placed point the same way: the artist confirmed NORTHEAST at positions 26 to 34, a bearing line is carved into the courtyard compass stone on the intercardinal axis, and the rose is a 16-point compass (22.5° per point) on which east-northeast falls at exactly 67.5°. Independent design elements agreeing on one bearing is strong evidence that the wayfinding reading is intended, not an artifact of the reconstruction. Scope: this constrains the bearing region of the message, a few bits, not the full 97 characters and not the key.

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, the great-circle initial bearing from CIA headquarters in Langley, Virginia to the Weltzeituhr at Alexanderplatz — the artist-confirmed referent — is 44.4° from north, within 0.6° of exact northeast (45.0°). The reconstructed closing phrase is geodetically exact, not approximate. Because this final NORTHEAST lies in the reconstructed portion of the text (the anchor NORTHEAST is the earlier one at positions 26 to 34), the bearing is a genuine consistency check on the inferred tail: it is computed from public coordinates and the artist-identified referent only (measured 2026-07-02).

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 rose-East rule (June 2026)

The three hardest helper-card values in the system, the Z2 correction deltas at C, K, and S, turn out to follow the compass rose itself:

The required caveat, never separated from the sentence above: two of sixteen wrap conventions place the class on East, the canonical one and its point-mirror, which is the theoretical minimum for any such claim; the engraved rose fixes the clockwise chirality, and North is the bearing origin the sculpture's own EAST NORTHEAST language uses. Conservative chance of the East ring-rule under value shuffling: 0.73% (0.108% granting East's a-priori role in the gate). Status: A-class candidate for these three cells only; the wrap procedure and the 16-per-ring step are precommitted for archive/K5 confirmation.

One rose cell is now publicly derived (July 2026). The July 1 transitive-closure sweep reaches the K cell without the fitted card: position 69 (N of BERLIN) with f(T) = 13 forces g_Z2(K) = 19, and subtracting the publicly confirmed scaffold g_Z1(K) = 13 gives delta(K) = 6, exactly the rose rule's ring-2 value (16 × 2 mod 26). The K cell of the rule no longer rests on the plaintext-fitted card. delta(C) = 16 and delta(S) = 22 remain the rule's genuine out-of-sample predictions, precommitted for archive/K5. The rule's overall grade is unchanged (A-class candidate pending an external witness); the K value itself is now derived.

East now selects twice in K4, in two independent layers: the gate adds its one-bit correction exactly on the E-ray cells of the grid, and the three hardest helper-card values sit exactly on the East ray of the rose-wrapped alphabet. The same privilege the plaintext announces, THE COMPASS ROSE IS HERE / EAST NORTHEAST, is the privilege the machine uses.

The full evidence package (the unique selector among 598 modular classes, the granularity uniqueness of the 8-wind rose, and the photo-witnessed clockwise label order) is on the appendix.

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 Quagmire III variant with a physical keystream and a one-bit gate. The keyword is KRYPTOS, the same one used for K1, K2, and K3. The keystream is the tableau side of the copper screen: for each K4 ciphertext position, the helper letter is the character on the back of the sculpture at the same row and column. For each of the 97 positions:

r = ( f(C) + g_state(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 physically off the tableau side of the sculpture at the same row and column. f(C) is the row-identity card, it tells you which row of the KRYPTOS-keyed tableau the cipher letter belongs to. g_state(T) is the column offset from standard Quagmire III lookup; one of four helper cards (g_X, g_Y, g_Z1, g_Z2), selected by which of the four 31-cell passes the position belongs to. The gate is a one-bit adjustment (0 or 1) fixed by the position under a declared rule, plaintext-independent by construction (see the note on the How It Works page). The final subtraction produces the plaintext letter P.

The honest split: the KRYPTOS keyword, the gate rule, and the helper letters come from the sculpture and public clues, while most f and g values are back-solved from the plaintext and reproduce the reconstruction by construction. The genuine forward exceptions are the 11-of-26 f-spine, the Z1 scaffold mask, and the rose-East rule at the three hard Z2 cells (above). See the Field Guide for the four-step on-site procedure, or the verification page for the per-position grade map and card provenance.

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 gate map, see How It Works. For the full 97-row reconciliation table, see Verify It Yourself.

Cipher classification

K4 is a Quagmire III variant, a keyword Vigenère with a separate column key, using the KRYPTOS-keyed tableau printed on the sculpture as its lookup square. The keyword is KRYPTOS (shared with K1–K3). The keystream comes from the tableau side of the copper screen: at each K4 ciphertext position, the helper letter is the character on the back of the sculpture at the same row and column. A one-bit gate (fixed by position) adjusts the final shift. The sculpture itself is the key.

The decryption formula: r = (f(C) + g_state(T)) mod 26, then R = r + gate (a one-bit value fixed by position), 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), each with its own helper card derived from the back-side letters in that pass. For Z2, the visible footer is standard alphabet text, but the lookup basis is converted into KALPHA state before the helper-card value is read.

A small set of master constants recurs throughout the derivation, all sourced from on-site artifacts: 4 (tail multiplier from the T clue), 13 (scaffold default), 19 (bridge offset from K1/K2/K3 misspellings), 3 and 11 (compass seeds), and 24 (seam base). See the Field Guide for the four-step on-site procedure or the verification page for the full helper-card layer.

How every clue maps to a solve step

In the reconstruction, each of Sanborn's clues is read as performing a specific function in the decoding procedure. The chains themselves are public; turning several of them into absolute values requires fitted entries (the A/E/I misspelling family closes only relationally), and the compass-seed readings are interpretive pending a blind test. Per-entry grades are in the claim status summary in the downloads:

What remains

The written method is complete and executable: the decoder, the physical helper keystream, the gate rule, and every card value are specified, and the machine reproduces the reconstruction at all 97 positions when run forward. The second layer is the literal back of the copper screen, exactly as we read Sanborn's 2006 K2 correction ("X LAYER TWO") to hint. The honest qualifier: most card values are back-solved from the plaintext, so this is internal consistency, not independent recovery.

What remains is external. The largest open object is the Y-pass card (g_Y), followed by the rose rule's step-16 witness, the wrap procedure, and the blind gate/ray field read; the full register is on the appendix. Sanborn has confirmed four plaintext anchors but has not released the coding procedure, and the sealed Smithsonian records are embargoed until 2075.

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

Continue

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?

The plaintext was recovered from Sanborn's archive in 2025, not cracked. The mechanism presented here is a reconstruction built backward from that text and the four artist-confirmed anchors: the helper keystream is read physically off the back of the sculpture (for each position, the character on the tableau side at the same row and column), a one-bit gate fixed by position adjusts the shift, and the substitution cards are back-solved so that standard Quagmire III subtraction reproduces the text at every position.

Why didn't anyone solve K4 before?

Every prior attempt searched for a keyword for the keystream, a word or phrase like PALIMPSEST or ABSCISSA from K1 and K2. In this reconstruction the keystream isn't a word. It's the back of the sculpture itself: a 97-character physical sequence made of the cap WXZK, the full Y row, the full Z row, and a standard alphabet footer that hands off into the Z2 KALPHA-state basis. We read Sanborn's 2006 correction to K2, replacing the slipped ending "ID BY ROWS" with "X LAYER TWO," as the hint: there are two physical layers, and the reconstruction reads both. The harder truth, though, is that the substitution chart itself was authored and sealed; no public clue forces it, which is why no keyword search could ever have worked.

Is K4 officially confirmed?

The four anchor words are confirmed by the artist. The full 97-character plaintext was recovered from Sanborn's Smithsonian archives in September 2025 by Jarett Kobek and Richard Byrne, authenticated by Sanborn, and not publicly disclosed; the coding method and key were not part of what was found. The 97 characters on this site are a reconstruction consistent with the anchors. 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 reconstruction documented here, 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. On the tableau side at the same row and columns, OBKR aligns with WXZK, the active X-pass cap of the helper keystream.

Who solved Kryptos K4?

No one has solved K4 cryptographically. The plaintext was recovered from Jim Sanborn's Smithsonian archives in September 2025 by writer Jarett Kobek and journalist Richard Byrne, who emphasized they had not solved the cipher. The mechanism documented on this site is a reconstruction by Matt Lacy, built backward from the recovered and anchored text, internally consistent at all 97 positions, and bounded honestly by what public data can force. K1–K3 were solved by CIA analyst David Stein (1998, classified) and cryptographer Jim Gillogly (1999, public).