Self-keying (autokey) cipher after structured letter rearrangements (consistency filter)

About 4.2 million structured rearrangements (every column order at widths 2 to 10, keyword columnar, rail fence, routes, fixed-step readings and others) were each combined with self-keying ciphers with starting keys of 1 to 20 letters (plaintext- or ciphertext-keyed Vigenere, Beaufort or Variant Beaufort, on the standard and KRYPTOS alphabets). For the plaintext-keyed form only the few known letters that end up exactly one starting-key length apart can be checked, 3 to 5 per setting here. 2,054 settings passed all of their checks. With so few checks that is weak evidence either way, and those settings were not followed up, so this record does not rule the model out.

In plain English: Tried self-keying ciphers after about 4.2 million structured letter rearrangements. For the plaintext-keyed form only a handful of known letters can be checked for each setting, and 2,054 settings passed their checks. They were not followed up, so this search neither found a solution nor ruled the idea out.

NOISE Tier 3

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: 4,207,963
Best Score: N/A
Confidence: Tier 3: Partial or statistical. May warrant re-testing under different assumptions.
Script: scripts/two_system/e_mitm_autokey_transposition.py

Scope Limitations

This elimination does not rule out:

Self-keying after a letter rearrangement, including the 2,054 settings that passed this filter and were never decrypted in full
Rearrangements outside the listed families
Starting keys longer than 20 letters

Assumptions

Letters rearranged first, then the self-keying cipher applied
Known letters at their standard positions in the plaintext
A setting passes if every checkable known letter agrees and at least 3 can be checked

Reproduce

PYTHONPATH=src python3 -u scripts/two_system/e_mitm_autokey_transposition.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