Many people enjoy solving word games such as the daily Cryptoquote puzzle, which uses a simple substitution cipher to disguise a witty or wise quote by a famous person. A common way to attack the puzzle is frequency analysis. In frequency analysis you identify letters and pairs of letters (bigrams)
It usually takes more than three weeks to prepare a good impromptu speech. --Mark Twain In the popular Cryptoquote puzzle, you are presented with an enciphered version of a quote by a famous person. One of the appeals of the puzzle for me is reading the deciphered quote, such
Double, double toil and trouble; Fire burn, and caldron bubble. Macbeth, Act IV, Scene I For the cyptanalyst or recreational puzzle solver, "double double" does not lead to toil or trouble. Just the opposite: The occurrence of a double-letter bigram in an enciphered word puzzle is quite fortunate. Certain double
In last week's article about the distribution of letters in an English corpus, I presented research results by Peter Norvig who used Google's digitized library and tabulated the frequency of each letter. Norvig also tabulated the frequency of bigrams, which are pairs of letters that appear consecutively within a word.
It's time for another blog post about ciphers. As I indicated in my previous blog post about substitution ciphers, the classical substitution cipher is no longer used to encrypt ultra-secret messages because the enciphered text is prone to a type of statistical attack known as frequency analysis. At the root
Today is my fourth blog-iversary: the anniversary of my first blog post in 2010. To celebrate, I am going to write a series of fun posts based on The Code Book by Simon Singh, a fascinating account of the history of cryptography from ancient times until the present. While reading