Dan Brown’s most popular novel, The Da Vinci Code, is filled with secrecy and code breaking. One of the more creative elements that Brown wrote about was a cryptex. The term cryptex comes from the words cryptology (the study of code breaking) and codex (an ancient type of book). The main characters Robert Langdon and Sophie come into possession of a cryptex on their journey to find the Holy Grail. A cryptex is a cylindrical object that has a message locked inside. There are multiple dials along its body, which have a ring of letters on them. Once the letters are aligned in the proper order to spell a word then the cryptex opens, similar to a bicycle lock. A cryptex is cleverly designed so that any attempt to force it open results in a vial of vinegar to break which will dissolve the message. Therefore, the only way to open it is with the code word.
In the novel, there were two cryptexes, each with a five letter code. How secure is a cryptex with a five letter combination? Each dial on the cryptex has a full alphabet of 26 letters. This means that any one of these 26 letters could be the first letter of the code, any could be the second letter, or the third, and so on. Raising 26 to the 5th power shows that there are 11,881,376 combinations of letters, or unique codes possible. If a code breaker tried to crack this code by “brute force” or trying every combo at a rate of 1 attempt every 5 seconds, then it would take almost two years to open it. If an additional sixth ring of letters was added, then the number of combinations soars to 308,915,776. The chance of correctly guessing a five letter code on the first try is .00000842% Thus, the contents of the cryptex are amazingly secure.