Fractionation

Methods that break each letter into smaller pieces (like grid coordinates), scramble those pieces, then reassemble them into new letters. Includes Bifid, Playfair, Four-Square, and ADFGVX.

What we tested: Bifid, Playfair, Four-Square and similar ciphers built on a 5×5 square are impossible for K4 in their standard form, because the square holds only 25 letters (I and J are usually merged) but all 26 letters appear in K4's ciphertext. ADFGVX is ruled out for a different reason: its output uses only the six letters A, D, F, G, V and X and always has an even length, while K4 uses all 26 letters and has 97. These are logical impossibilities, not just search results.

19 eliminations recorded.

Title	Configs	Best	Verdict	Tier
K2 coordinates as straddling checkerboard configuration Tested a method that encodes letters as variable-length digit sequences. 9.2 million key/parameter combinations were tested.	9,223,974	N/A	NOISE	N/A
Straddling checkerboard digit-level attack on K4 Tested a method that encodes letters as variable-length digit sequences. 86 thousand key/parameter combinations were tested.	86,066	N/A	NOISE	N/A
Non-algebraic process-based ciphers on 5-wide KA Polybius grid Tested a method that converts letters to number pairs using a grid (Polybius square). 17 thousand key/parameter combinations were tested.	17,262	N/A	NOISE	N/A
Modified Polybius Grids Tested a method that converts letters to number pairs using a grid (Polybius square). 8 thousand key/parameter combinations were tested.	8,374	6/24	NOISE	N/A
Morse code misspellings produce grid cipher key material; straddling checkerboard explains 73->97 expansion Morse code misspellings produce grid cipher key material, using a method that encodes letters as variable-length digit sequences. 535 key/parameter co…	535	5/24	NOISE	N/A
Bifid 5x6 Ka Tested a method that breaks letters into grid coordinates, mixes them, and reassembles (Bifid cipher).	N/A	7/24	NOISE	N/A
5x5 Bifid cipher (proof of impossibility) A 5x5 grid holds only 25 letters (I and J merged), but all 26 letters appear in K4, using a method that breaks letters into grid coordinates, mixes th…	N/A	N/A	ELIMINATED	Tier 1
Bifid 6x6 at periods 2-49 (algebraic contradiction analysis) Tested a method that breaks letters into grid coordinates, mixes them, and reassembles (Bifid cipher).	N/A	N/A	INCONCLUSIVE	N/A
Bifid 6x6 cross-group algebraic elimination for periods 9-14 Tested a method that breaks letters into grid coordinates, mixes them, and reassembles (Bifid cipher).	N/A	N/A	NOISE	N/A
Polybius-coordinate cipher exploit: running-key + SA Tested a method that converts letters to number pairs using a grid (Polybius square).	N/A	N/A	NOISE	N/A
Polybius fractionation as inner cipher + null mask as outer layer Tested a method that converts letters to number pairs using a grid (Polybius square).	N/A	N/A	NOISE	N/A
Polybius Row Clustering Audit Tested a method that converts letters to number pairs using a grid (Polybius square).	N/A	N/A	NOISE	N/A
Polybius Split Coordinate Tested a method that converts letters to number pairs using a grid (Polybius square).	N/A	N/A	NOISE	N/A
Row gradient validation for keystream present/absent values on KA Polybius grid Tested a method that converts letters to number pairs using a grid (Polybius square).	N/A	N/A	NOISE	N/A
Row-Markov regularized keystream SA: 4 conditions testing whether Polybius row structure helps decode K4 Tested a method that converts letters to number pairs using a grid (Polybius square).	N/A	N/A	NOISE	N/A
Polybius Row Selection Mask Tested a method that converts letters to number pairs using a grid (Polybius square).	N/A	N/A	NOISE	N/A
Full disproof (E-PLAYFAIR-01) Tested a method that encrypts pairs of letters using a 5×5 grid (Playfair cipher).	N/A	N/A	ELIMINATED	N/A
Trifid extended (E-S-42b) Tested a method that breaks letters into three-part coordinates and recombines them (Trifid cipher).	N/A	N/A	NOISE	N/A
Trifid p16 (E-S-44) Tested a method that breaks letters into three-part coordinates and recombines them (Trifid cipher).	N/A	N/A	ELIMINATED	N/A