9 Complete columnar transposition ciphers
In 1935, somebody sent the anonymous message shown in Figure 9-1 to President Franklin D. Roosevelt.1, 2 While the second line, OR ELSE YOU DIE, is readable, the first is obviously encrypted. We can recover the plaintext by writing the message in lines of two letters each:
ND
OI
MD
EY
LO
AU
EE
TV
IE
BR
Figure 9-1: An anonymous encrypted message sent to President Franklin D. Roosevelt in 1935
Notice that, from top to bottom, the second column reads, DIDYOUEVER. The first column, from the bottom up, ...
Get Codebreaking now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.
