What is a Complete Columnar Transposition?
Choose a row width, and order the columns randomly. Write the plaintext horizontally in order, with each row being the row width. Then write each column, using the random ordering.
2 3 1 r i p v a n w i n k l e
CT: PNNER VWKIA IL
Vulnerabilities of Complete Columnar Transposition
When used by itself, the frequency count of a complete columnar transposition ciphertext will resemble English.
How to crack a Complete Columnar Transposition
The key length will be at least two. Write the CT into two columns, rearrange them, and if the plaintext is not apparent, try three columns, and so on. This cipher can be solved with brute force computing methods.