“F13.4c at key lengths 6-19 (D3): one free alphabet with a periodic key, ciphertext only, K4 against 100 fresh shuffles climbed by 0236's frozen search, closed at the measured power”

1. Write a scrambled alphabet and a key of, say, 11 numbers.
2. To read the ciphertext, take each letter's place in the alphabet, subtract the key number for that position (Beaufort: subtract the place from the key), and read the alphabet at the result.
3. A computer searches alphabets and keys for the most English-looking reading of K4, without looking at the known words.
4. The same search runs on 100 scrambled copies of K4.
5. K4 counts only if it reads better than every copy; then the 24 known letters are checked.

A planted message from K3's own words, a shuffled alphabet and a key of 3, Beaufort form, no known letter:

  alphabet, true   CKEMJNZWSYGDRPVFBHOAQULXIT
  carved           TUMWQZNVALJNNTWAEBRQETUMIURULMRRRMJMPPVLXYNYMTQBEVNXGASHZDCMBGCTBLPGZNVYBQBTUMRQPUNWTUWAGELCULK
  alphabet, found  TUYVAIMHKQPEWRJLDZXBSCNGFO
  reading          THEJOTAIRESCAKINGFROMTHECHAOBERCASSEDFJEDLAMETOFLICKERMUTPREHENTLYDETAILHOFTHEROHOWITHINEMERDETRN

  letters right: 81 of 97

F13.4c: a periodic key on one free alphabet (Quagmire III with an unknown order, both forms), solved from the ciphertext alone: the search never reads the 24 known letters (program.md, F13); gate 2 checks them at keep time. 0236's design-2 tempering without known letters, 3 runs x 16 replicas x 625 rounds x 1000 moves, MIX8m rescoring (0233). F13.1 puts one free alphabet with a key within reach of 97 letters to length 19 by quadgrams; 0236 found the search's power falls from 7/8 at 5 to 2-5/8 at 6-19. Statistic: per cell, K4's MIX8m against the shuffles' (z); over the 28 cells the largest z against the shuffles' own largest z. Clue entries C27(c), C5(a).

K4 inside its shuffles: largest z over the 28 cells with p above 0.05; no cell where K4 beats all 100. Plant power as 0236 (2-5 of 8 at 6-19). K4's readings put at most 5 of the 24 known letters in place (harness gate 2).

1. Texts: K4 and 100 shuffles of K4 (seed 2560).
2. Each text at every key length 6-19 and both forms (Beaufort, added): 0236's climb(), unchanged.
3. Plants: 8 per length at 6, 7, 8, 10, 13, 16, 19 (0236's rule: Carter test windows, half with X stops, a random alphabet and key, forms alternating), 6 own shuffles each; found when above all its own copies.
4. Per cell: K4's rank among the 100 and its z; the statistic is the largest z, its p from the shuffles' own largest z.

All 28 candidates, lowest loss first.

F13.4c 6-19: K4 statistic 1.47 at 11/beaufort, p 0.842 against 100 shuffles; cells with K4 above all 0 of 28; plant power L6 3/8, L7 5/8, L8 4/8, L10 4/8, L13 5/8, L16 4/8, L19 2/8

What was searched, as the harness recorded it.

item

F13.4c lengths 6-19 (D3)

search reads known letters

no

forms

beaufort, added

search

0236's climb, unchanged (imported): 0140's parallel tempering with no known letter, 3 runs x 16 replicas x 625 rounds x 1000 moves; MIX8m rescoring

k4 copies

100

cells

28

plant power

6

3, 8

7

5, 8

8

4, 8

10

4, 8

13

5, 8

16

4, 8

19

2, 8

plant letters right

6

9, 7, 11, 12, 26, 34, 2, 17

7

9, 7, 7, 2, 6, 2, 24, 10

8

18, 4, 25, 9, 11, 13, 3, 21

10

12, 8, 22, 23, 13, 6, 10, 10

13

7, 6, 16, 10, 13, 2, 12, 4

16

10, 6, 11, 6, 5, 2, 5, 10

19

8, 12, 10, 7, 7, 1, 5, 5

k4 z by cell

6/beaufort

-1.573

6/added

-0.952

7/beaufort

-0.009

7/added

-0.915

8/beaufort

-2.01

8/added

-0.66

9/beaufort

0.697

9/added

-2.769

10/beaufort

-0.565

10/added

0.913

11/beaufort

1.469

11/added

-1.215

12/beaufort

-1.398

12/added

0.615

13/beaufort

-1.176

13/added

0.171

14/beaufort

1.447

14/added

1.377

15/beaufort

0.39

15/added

-0.724

16/beaufort

0.104

16/added

0.104

17/beaufort

-0.413

17/added

-1.743

18/beaufort

-2.717

18/added

0.104

19/beaufort

0.383

19/added

-0.493

k4 copies at or above by cell

6/beaufort

93

6/added

81

7/beaufort

49

7/added

81

8/beaufort

96

8/added

73

9/beaufort

24

9/added

100

10/beaufort

69

10/added

17

11/beaufort

11

11/added

90

12/beaufort

93

12/added

28

13/beaufort

89

13/added

42

14/beaufort

9

14/added

10

15/beaufort

33

15/added

74

16/beaufort

48

16/added

43

17/beaufort

66

17/added

94

18/beaufort

99

18/added

42

19/beaufort

39

19/added

67

k4 cells above all copies

0

k4 statistic

1.469

k4 best cell

11/beaufort

k4 p

0.842

k4 known letters in place by cell

6/beaufort

0

6/added

2

7/beaufort

1

7/added

1

8/beaufort

0

8/added

0

9/beaufort

2

9/added

2

10/beaufort

3

10/added

3

11/beaufort

3

11/added

3

12/beaufort

3

12/added

1

13/beaufort

3

13/added

1

14/beaufort

0

14/added

2

15/beaufort

1

15/added

2

16/beaufort

1

16/added

1

17/beaufort

3

17/added

3

18/beaufort

3

18/added

1

19/beaufort

1

19/added

1

climbs

3,220

exhaustive

no

compute seconds

8,485

modal cost estimate

3220 climbs x about 10 s (0236) = about 9 core-hours, about $0.6 of Modal credit