Running Key Cipher
Earlier today I was given a book/running key cipher to try to decrypt. I have experimented with dozens of different types of ciphers, but somehow this very basic one slipped past me and I had never heard of it before. It is really quite simple: the sender and receiver of the cryptographic information first agree on a book that they will each use as their key. The book is important, because the cipher utilizes page numbers, line numbers, and word numbers in order to create the secret message. The cipher is formatted as shown here:
x1,y1,z1;x2,y2,z2;x3,y3,z3;… x=page, y=line, z=word
So if you saw
2,7,1;3,2,1 this would mean the message is just two words long. The first word is on page 2, line 7, word 1. The second word is on page 3, line 2, word 1.
Let’s give it a shot. In my example, I’ll use a fairly popular book found on many shelves: The 7 Habits of Highly Effective People by Stephen Covey. Here is the ciphertext; let me know if you were able to decrypt it!
22,1,3; 17,14,12; 128,14,1; 186,7,9; 97,3,7; 256,21,6; 57,3,5; 24,1,10; 301,5,5