1. Rail Fence Cipher
Definition:
The letters of the plaintext are written in a zig-zag pattern (rails) and then read row-wise to form the ciphertext.
Example (Depth = 3):
-
Plaintext:
WEAREDISCOVERED -
Zigzag writing:
W . . . R . . . D . . .
. E . E . D . C . V . R
. . A . . . I . . . E .
- Ciphertext:
WRDEEDCVREAIE
Merits:
-
Preserves letter frequency, making frequency analysis harder.
-
Adds confusion by changing the order of letters.
Demerits:
-
Still vulnerable to pattern detection.
-
Requires knowledge of the transposition key (e.g., number of rails).