The letters ride a diagonal zigzag fence and are read off rail by rail.
transposition cipher
trivial to break
American Civil War
Fence-line ciphers; the scytale as the ancient forerunner
encrypt · decrypt · cryptanalysis
Slide the rail count (and the offset) — the fence re-draws and the plaintext candidate updates. When the rows read like English, you have it; the meter only measures how English-like each setting looks.
Rails: 3
Offset: 0
English-likeness
0