Experiment 101

“An interrupted key: the key word starts again at the first letter of every word of the message”

Every periodic test so far ran the key straight through the message. A classical hand variant restarts the key word at each new plaintext word, so the key letter depends on the place inside the word, not in the message. The cribs supply the word breaks (EAST NORTH EAST or EAST NORTHEAST; BERLIN CLOCK or BERLINCLOCK), which makes the test exact.

revertedstatus
a new rootparents
42 stime, all phases
0candidates
0/24known letters
unclocked
1

The experiment method

What the method does with the 24 known letters.

With a secret word as key, one usually runs it along the whole message. A trick to hide the pattern is to start the secret wordthe secret word The word or string a cipher needs besides the method. again at the beginning of every word of the messagethe message The 97 letters of English that Jim Sanborn wrote and enciphered.. We know where some words begin, because the known lettersthe known letters Sanborn has confirmed that positions 22 to 34 of the message read EASTNORTHEAST and positions 64 to 74 read BERLINCLOCK. spell EAST, NORTH, EAST, BERLIN and CLOCK. So for each length of secret word we can check whether starting it over at each of those words fits the carved lettersthe carved letters The 97 letters cut into the copper at the CIA, shown at the top of every experiment page..

Words in the margin are defined on the glossary page.

1.1

The method at work

The carved letters go in at the top; the reading comes out at the bottom.

OBKRUOXOGHULBSOLIFBBWEASTNORTHEASTOTWTQSJQSSEKZZWATJKLUDIAWINFBBERLINCLOCKWGDKZXTJCDIGKUHUAUEKCARIN: THE COPPER, ALL 97 LETTERS, THE 24 KNOWN PLACES IN ACCENTsplit the known letters into words and restart the key at each: EAST NORTH EAST, BERLIN CLOCKEASTNORTHEASTBERLINCLOCKplace in the word: which key letter each takes012301234012301234501234key value each needs on the sculpture's alphabet, Vigenere (last digit)101815235290217255198700first letters of the words need 1, 1, 2, 11, 9: one key letter cannot be all of themshortest key, 1 to 26 letters, that fits each split, in all 8 tablesEAST|NORTH|EAST + BERLIN|CLOCKK4: noneten scrambled coppers: noneEAST|NORTH|EAST + BERLINCLOCKK4: noneten scrambled coppers: noneEAST|NORTHEAST + BERLIN|CLOCKK4: noneten scrambled coppers: noneEAST|NORTHEAST + BERLINCLOCKK4: noneten scrambled coppers: noneEASTNORTHEAST + BERLIN|CLOCKK4: noneten scrambled coppers: noneOUT: NO READING; NO RESTARTED KEY FITSEASTNORTHEASTBERLINCLOCK
the key

Some hand ciphers restart the key at every word, so word boundaries leave a mark. Here the known letters are split into words in all five sensible ways and the key starts again at each.

the check

Letters at the same place in their words take the same key letter. With the sculpture's table the first letters of EAST, NORTH and EAST need 1, 1 and 2: already a clash.

the bound

No key of 1 to 26 letters fits any split in any of the 8 tables, on K4 or on any of ten scrambled coppers: the cribs alone rule the idea out.

2

Best candidate against the known letters

This experiment produced no candidate: the search ruled everything out before a full text was built. Its product is the bounded negative in section 7.

3

Walkthrough, by hand

Redo the method on a few letters with pencil and paper.

  1. Split the known letters into words: EAST at 22-25, NORTH at 26-30, EAST at 31-34, BERLIN at 64-69, CLOCK at 70-74.
  2. Restart the key at each word: E at 22, N at 26, E at 31, B at 64 and C at 70 all take the first key letter.
  3. On the sculpture's alphabet with Vigenere, the key letter for E to F at 22 and for N to Q at 26 must then be the same.
  4. Do this for each offset, key length 1-26, the other word splits and table rules.
the worksheet: the first steps by hand, on squared paper
WORDS EAST NORTH EAST BERLIN CLOCK, KEY RESTARTED AT EACH; SCULPTURE'S ALPHABET, VIGENEREplacelettercopperin wordkey value22EF0123AL11024SR22125TV31826NQ0127OQ11528RP2229TR32330HN4531EG0232AK11933SS20placelettercopperin wordkey value34TS3264BN01165EY11766RP2267LV3568IT41569NT51170CM0971LZ1872OF2773CP32074KK40Every word's first letter takes key letter 0: places 22, 26, 31, 64 and 70 need 1, 1, 2, 11 and 9. They must be equal: dead for every key length.
4

Worked example, generated

The same steps run by the code on the real letters.

words EAST NORTH EAST BERLIN CLOCK, key restarted at each; sculpture's alphabet, Vigenere

place  letter  copper  offset in word  key value
   22       E       F               0          1
   23       A       L               1         10
   24       S       R               2         21
   25       T       V               3         18
   26       N       Q               0          1
   27       O       Q               1         15
   28       R       P               2          2
   29       T       R               3         23
   30       H       N               4          5
   31       E       G               0          2
   32       A       K               1         19
   33       S       S               2          0
   34       T       S               3          2
   64       B       N               0         11
   65       E       Y               1         17
   66       R       P               2          2
   67       L       V               3          5
   68       I       T               4         15
   69       N       T               5         11
   70       C       M               0          9
   71       L       Z               1          8
   72       O       F               2          7
   73       C       P               3         20
   74       K       K               4          0
5

Hypothesis, for a cryptanalyst

Family, key space, the constraint under test, and the clues it reads.

Scheidt: 'simple, can be remembered' (C5) and he 'masked the English language' (C4); an interrupted key is a standard field method (Friedman's 'interrupted key') that hides the period. Model: key letter of a plaintext letter = keyword[(offset inside its word) mod L], L = 1-26, the keyword restarting at each word; EAST and BERLIN assumed to start words (E at 22 and B at 64). Segmentations: EAST|NORTH|EAST, EAST|NORTHEAST, EASTNORTHEAST as one word, crossed with BERLIN|CLOCK and BERLINCLOCK (five splits). Eight tableau classes (standard or KRYPTOS plain and cipher alphabets, Beaufort or not). Known letters with the same in-word offset mod L must force the same key value. Ten shuffled coppers.

6

Prediction

Written before the run; the result decides it.

No segmentation, key length or table rule fits all 24 known letters except at key lengths long enough that no two known letters share a key letter (L at least 9 for the segmentations with NORTHEAST, 6 otherwise); counts at those lengths match the coppers'. Zero candidates.

7

Method

  1. For each segmentation, give each known letter its offset inside its word.
  2. For each key length and class, compute the forced key value at each known letter and check that letters with equal offset mod L agree.
  3. Record the smallest consistent L and the number of checks.
  4. Repeat on ten shuffled coppers.
8

Result and bounds

The harness's record: candidates, gates, loss, and the negative result this experiment leaves behind.

0candidates returned
0passed every gate
0/24known letters, best
–lowest loss
nonechampion before

Smallest key length consistent with at least one check (None: no length 1-26 fits), K4 vs controls: EAST|NORTH|EAST + BERLIN|CLOCK: None vs [None, None, None, None, None, None, None, None, None, None]; EAST|NORTH|EAST + BERLINCLOCK: None vs [None, None, None, None, None, None, None, None, None, None]; EAST|NORTHEAST + BERLIN|CLOCK: None vs [None, None, None, None, None, None, None, None, None, None]; EAST|NORTHEAST + BERLINCLOCK: None vs [None, None, None, None, None, None, None, None, None, None]; EASTNORTHEAST + BERLIN|CLOCK: None vs [None, None, None, None, None, None, None, None, None, None]. K4 settings consistent with 3+ checks: 0.

What was searched, as the harness recorded it.

family
interrupted key restarting at every plaintext word
segmentations
EAST|NORTH|EAST + BERLIN|CLOCK, EAST|NORTH|EAST + BERLINCLOCK, EAST|NORTHEAST + BERLIN|CLOCK, EAST|NORTHEAST + BERLINCLOCK, EASTNORTHEAST + BERLIN|CLOCK
key lengths
1, 26
classes
8
by segmentation
EAST|NORTH|EAST + BERLIN|CLOCK
k4 smallest L with checks
None
controls
None, None, None, None, None, None, None, None, None, None
EAST|NORTH|EAST + BERLINCLOCK
k4 smallest L with checks
None
controls
None, None, None, None, None, None, None, None, None, None
EAST|NORTHEAST + BERLIN|CLOCK
k4 smallest L with checks
None
controls
None, None, None, None, None, None, None, None, None, None
EAST|NORTHEAST + BERLINCLOCK
k4 smallest L with checks
None
controls
None, None, None, None, None, None, None, None, None, None
EASTNORTHEAST + BERLIN|CLOCK
k4 smallest L with checks
None
controls
None, None, None, None, None, None, None, None, None, None
k4 live with 3 plus checks
none
n k4 live with 3 plus checks
0
controls
10 shuffled coppers (seed 101), identical test

How this experiment sits among the others is on the lineage page; its family's open hypotheses are on the families page.

Rendered from the record on 2026-10-18 12:26 UTC; updated after every experiment.
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