Self-keying (autokey) cipher on the 73 letters left by a column-band filler model

Self-keying ciphers in six forms on the standard and KRYPTOS alphabets, plus fixed-step keys and keys made from the carved text itself, tried on 73-letter texts. Each text comes from laying the sculpture's full cipher text out in 28 rows of 31 letters and treating the 24 K4 letters in columns 8 to 16, apart from one kept column, as filler. Nine versions (one per kept column), 46,170 settings, best 6 of 24 known letters, which is chance level. Removing the filler letters changes both the text and where the known letters sit, so this is a different test from self-keying on all 97 carved letters.

In plain English: Self-keying ciphers in six forms on the standard and KRYPTOS alphabets, plus fixed-step keys and keys made from the carved text itself, tried on 73-letter texts, using a self-keying (autokey) method, where the key starts with a short word and then continues with letters of the message itself. Every combination within the stated scope was tested (46 thousand configurations); none produced a valid solution. This record is negative within the tested scope.

NOISE Tier 2

How to read this record

Verdict – ELIMINATED (ruled out within the tested scope), NOISE (nothing beyond what chance produces for a search of this size; also shown when a record stored no verdict of its own), INCONCLUSIVE (the test left candidates or options standing, or could not decide, so it does not rule the method out), INTERESTING (slightly above random, almost certainly coincidence), SIGNAL (statistically unusual, warrants investigation), or FULL MATCH (all 24 known letters correct).
Confidence Tier – Tier 1 = mathematical proof, valid while its stated assumptions hold. Tier 2 = every possibility within the stated scope tested. Tier 3 = partially tested or sampled. Tier 4 = not yet properly tested.
Configs Tested – How many different key/parameter combinations were tried.
Best Score – How many of the 24 known plaintext letters the best attempt matched (out of 24). N/A means no such score could be read from this record.
Keystream Consistency (Bean) – Whether the key values at different positions are mathematically consistent with each other. The check only holds when the known letters stay in their carved positions (no letters rearranged or removed), and the full set used here assumes the standard A to Z alphabet.
Scope Limitations – What this elimination does not rule out.

Configs Tested: 46,170
Best Score: 6 / 24 known letters matched · low, no sign of a solution
Confidence: Tier 2: Exhaustive search under stated assumptions. Does not eliminate multi-layer variants.
Truth Tag: [INTERNAL RESULT]
Date Tested: 2026-03-12

Scope Limitations

This elimination does not rule out:

Other ways of choosing the 24 filler letters
Starting keys other than the 26 single letters, 25 keywords and the first 2 to 13 letters of those keywords
Running keys other than the carved text itself

Assumptions

Filler letters are the K4 letters in columns 8 to 16 of a 28-by-31 layout of the cipher text, minus one kept column
Known letters move to positions 13-25 and 47-57 of the 73 (counting from 0)

Reproduce

PYTHONPATH=src python3 -u scripts/grille/e_column_mask_autokey_01.py

Requires the kryptos repo, Python 3.11+, PYTHONPATH=src. Some recent scripts may not be in the public repository yet.

Found an error? Report on GitHub