K4 · live cryptanalysis

updated Wed, 29 Apr 2026 14:38:10 GMT

Kryptos K4 is the final unsolved panel of Jim Sanborn's 1990 sculpture at CIA Langley. The plaintext was recovered from accidentally-donated archive scraps in September 2025 — but the cipher itself remains undisclosed. This page tracks an open, multi-agent attempt to derive the method.

Phase 0 — Bootstrap complete
day 1experiments 1repos vendored 7candidates 0 / rejected 0 / verified 0f7241ef ↗
K4 — 97 chars · revealed plaintext (copper) · ciphertext (dim) · hover the grid to see the original ciphertext
O0
B
K
R
U
O5
X
O
G
H
U10
L
B
S
O
L15
I
F
B
B
W20
F
L
R
V
Q25
Q
P
R
N
G30
K
S
S
O
T35
W
T
Q
S
J40
Q
S
S
E
K45
Z
Z
W
A
T50
J
K
L
U
D55
I
A
W
I
N60
F
B
N
Y
P65
V
T
T
M
Z70
F
P
K
W
G75
D
K
Z
X
T80
J
C
D
I
G85
K
U
H
U
A90
U
E
K
C
A95
R
EAST←FLRVpos 21–24· released 2020
NORTHEAST←QQPRNGKSSpos 25–33· released 2020
BERLIN←NYPVTTpos 63–68· released 2010
CLOCK←MZFPKpos 69–73· released 2014

What we're measuring

K4 against a 10,000-string random uniform null. Z-scores against the null, not raw values.

IoC
0.0361
z = -0.85 vs random null
0.066 = English · 0.039 = uniform random
Chi² vs English
571
z = -0.49 vs random null
lower = more English-like
Quadgram / char
-8.03
z = 0.78 vs random null
−0.30 = English · −8.30 = uniform random
Top autocorrelation
lag 7 · z = +3.05
period attack family flagged
3σ at any single lag is suggestive · Bonferroni-adjusted p ≈ 0.06

Disclaimer: nothing here is a solution claim. A K4 candidate is considered verified only when 4 of 4 cribs decrypt at the correct positions, the non-crib regions form coherent English, the method re-derives correctly from spec alone, and the approach generalises. All four. No exceptions.

Operations

Real project activity. Plays through history once, then waits. The browser polls every 20 seconds for new events — when something new happens (commit, experiment run, finding logged), it appears here. No looped or canned content.

/Users/fredericlumiere/k4live · polling every 20s · last sync —