To decrypt a double transposition, construct a block with the right number of rows under the keyword, blocking off the short columns. Write the cipher in by columns, and read it out by rows.

Cryptanalyst Jim Gillogly created them using the Playfair, Double Playfair, and Double Transposition ciphers, respectively.

It’s Math Monday! In this third post in a series on columnar transposition ciphers, we look at a formula for the underlying permutation of a CTC and specialize it to the rail fence cipher.

Oranchak, a 46-year-old software developer in Virginia, said the 340 is what’s known as a transposition cipher. Most ciphers used today by computers rely on mathematics to scramble messages.

But the Bay Area killer’s 340-character cipher mailed to the San Francisco Chronicle has been cracked by an international team of code-breakers.

Tech Culture cryptography Code-breakers crack Zodiac Killer cipher after 51 years The Zodiac Killer's identity remains unknown By Shawn Knight December 13, 2020, 12:06 PM 14 comments ...