Codebusters Test Codebusters Transposition Ciphers 2

Question 1

In a keyword columnar transposition with the keyword BAND, in what order are the columns extracted?

Accepted Answer

2, 1, 4, 3 (alphabetical order: A, B, D, N)

Answer

Alphabetizing BAND gives A (column 2, rank 1), B (column 1, rank 2), D (column 4, rank 3), N (column 3, rank 4), so columns are extracted in order 2, 1, 4, 3.

Question 2

What is a double transposition cipher?

Accepted Answer

A cipher that applies two separate transposition operations to the plaintext in sequence

Answer

A double transposition cipher applies columnar (or another) transposition twice in succession, making it far more resistant to cryptanalysis than single transposition alone.

Question 3

When cryptanalyzing an unknown transposition cipher, what is a productive first step after confirming high IC?

Accepted Answer

Test different column counts by arranging ciphertext into grids and examining column-pair digraph frequencies

Answer

Trying different grid widths (column counts) and checking whether the resulting columns pair into plausible English digraphs is the standard attack on columnar transposition.

Question 4

With a 3-rail fence cipher, what is the pattern of rail assignments for successive letters?

Accepted Answer

1, 2, 3, 2, 1, 2, 3, 2, 1…

Answer

The rail fence zigzag with 3 rails follows the pattern 1→2→3→2→1→2→3…, bouncing between the outermost rails and reversing direction each time it hits rail 1 or rail 3.

Question 5

What does it mean when the last row of a columnar transposition grid is incomplete?

Accepted Answer

Some columns contain one fewer letter than others, which constrains how many letters can be in each column

Answer

When the message length is not a multiple of the keyword length, the last row is partially filled, meaning some columns have one extra letter and others do not — this structure is a clue for determining the grid dimensions.

Codebusters Test Practice Test

Codebusters Test Practice Test

Codebusters Test Codebusters Transposition Ciphers 2