Nomenclator (code plus cipher) with one fixed code group per word (proof of impossibility)
EAST appears twice in the known plaintext (positions 21-24 and 30-33, counting from 0) but is carved as FLRV the first time and GKSS the second, so a system that always turns the same word or letter into the same code cannot have produced K4 directly.
In plain English: A nomenclator replaces whole words (or letters) with fixed code groups. The word EAST appears twice in the known plaintext but is carved differently each time (FLRV, then GKSS), so a nomenclator with one fixed code per word cannot have produced K4 directly. A second encryption step on top, or a rearrangement of the letters, is not ruled out.
This record is negative within the tested scope.
ELIMINATED
Tier 1
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
- N/A
- Best Score
- N/A
- Confidence
- Tier 1: Mathematical proof. Holds as long as the ciphertext, the known-letter positions and the assumptions listed on this page are correct.
- Truth Tag
[DERIVED FACT]- Date Tested
- 2026-02-27
- Script
scripts/cfm/e_cfm_05_nomenclator_model.py
Scope Limitations
This elimination does not rule out:
- A nomenclator followed by a second, position-dependent encryption step (superencipherment)
- A nomenclator with more than one code group per word, or combined with a letter rearrangement
Assumptions
- Each plaintext word or unit maps to one fixed ciphertext code group
- No position-dependent layer
- Known letters line up with the carved letters at their stated positions
Related Research Questions
Reproduce
PYTHONPATH=src python3 -u scripts/cfm/e_cfm_05_nomenclator_model.pyRequires the kryptos repo, Python 3.11+, PYTHONPATH=src. Some recent scripts may not be in the public repository yet.
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