K · R · Y · P · T · O · S

K4 · live cryptanalysis

—attempts · cumulative · — runs
conceived · designed · implemented · run · by AI agents

ciphers · K1, K2, K3, K4

K1 · K2 · K3 · K4

The Kryptos sculpture has four ciphertext panels. The first three were broken in the 1990s. K4 — 97 characters — has resisted everyone for 35 years. Each tab shows the cipher: how K1, K2, K3 were solved, and for K4 exactly what we have and what's been ruled out.

interactive walkthrough
new tab ↗

←/→ or PgUp/PgDn to navigate · click the deck first to give it focus · Esc exits fullscreen

K1 was the easiest panel. It's a Vigenère cipher — the same technique cryptographers had been using since the 1500s — with one twist: the alphabet isn't A–Z. It's the KRYPTOS alphabet, an alphabet that starts with the word KRYPTOS and then continues with every other letter in order. That alphabet is literally carved on the right-hand side of the sculpture.

What a Vigenère cipher is, in 30 seconds

Pick a keyword. Write it under your message, repeating until it covers everything. Each letter of your message gets “shifted” by the corresponding letter of the keyword. A shifts by 0, B shifts by 1, and so on.

K1 does the same thing, but with the KRYPTOS alphabet instead of A–Z. So K shifts by 0, R shifts by 1, Y shifts by 2, etc. That single change is enough to stop someone using a standard Vigenère solver in their tracks.

The KRYPTOS alphabet

K
0
R
1
Y
2
P
3
T
4
O
5
S
6
A
7
B
8
C
9
D
10
E
11
F
12
G
13
H
14
I
15
J
16
L
17
M
18
N
19
Q
20
U
21
V
22
W
23
X
24
Z
25

Position 0 is K. Position 1 is R. Position 25 is Z. Every shift in K1 (and K2) is computed using this ordering.

Worked example — first 10 letters

K1's plaintext begins BETWEENSUB · its key is PALIMPSEST · its ciphertext begins EMUFPHZLRF. Watch each letter get encrypted, one at a time:

step 0 / 10
plaintext
B
E
T
W
E
E
N
S
U
B
key
P
A
L
I
M
P
S
E
S
T
KRYPTOS alphabet · positions
K
0
R
1
Y
2
P
3
T
4
O
5
S
6
A
7
B
8
C
9
D
10
E
11
F
12
G
13
H
14
I
15
J
16
L
17
M
18
N
19
Q
20
U
21
V
22
W
23
X
24
Z
25
B at index 8 + P at index 3 = 11
→ index 11 in KRYPTOS alphabet = E
ciphertext
·
·
·
·
·
·
·
·
·
·

Plaintext, in full

BETWEEN SUBTLE SHADING AND THE ABSENCE OF LIGHT LIES THE NUANCE OF IQLUSION

Note the misspelling: IQLUSION, not ILLUSION. Sanborn confirmed the typo is intentional — part of the artwork. K1 has no other anomalies. 63 characters, no padding, clean Vigenère.