Double columnar transposition (all keyword pairs, widths 5-15)

In plain English: Double columnar transposition (all keyword pairs, widths 5-15) — using two rounds of columnar transposition applied back-to-back. Every possible combination was tested (1.2 billion configurations) — none produced a valid solution. Best match: 15/24 known letters — slightly above random, almost certainly coincidence. This approach is ruled out within the tested scope.

NOISE Tier 2

How to read this record

Verdict – NOISE (no better than random guessing), 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 (permanent). Tier 2 = every possibility tested. Tier 3 = partially tested. Tier 4 = not yet 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).
Keystream Consistency (Bean) – Whether the key values at different positions are mathematically consistent with each other.
Scope Limitations – What this elimination does not rule out.

Configs Tested: 1,200,000,000
Best Score: 15 / 24 known letters matched · above random, likely coincidence (random guess would score: 0.0)
Keystream Consistency (Bean): FAIL
Checks whether the key values at different positions are mathematically consistent with each other.
Confidence: Tier 2: Exhaustive search under stated assumptions. Does not eliminate multi-layer variants.
Date Tested: 2026-02-15
Script: scripts/transposition/columnar/e_s_06_double_columnar.py

Scope Limitations

This elimination does not rule out:

Single-layer only. Does not eliminate double columnar as transposition step in multi-layer.

Assumptions

Direct positional correspondence
Both columns use widths 5-15
Standard alphabetic ordering

Reproduce

PYTHONPATH=src python3 -u scripts/transposition/columnar/e_s_06_double_columnar.py

Requires the kryptos repo, Python 3.11+, PYTHONPATH=src.

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