The Sudoku Cipher
- 1. The Sudoku Cipher Leandros Andreou, Antonios Furfaro, Nefeli Zikou Cryptology Course Center for Talented Youth Anatolia College & Johns Hopkins University Thessaloniki, Greece 12 July 2016 …Secure and fun
- 2. Scenario When death strikes a old man his fortune is exposed to his greedy close relatives who are willing to do anything in their power to get the money. Might even override the law… What should the old man do to protect his fortune so that only his beloved nephews have access to it? This is where a trusted lawyer aids him to hide the chest with the money and provides his nephews the instructions after the death of their uncle. But… the chest is LOCKED!!! How are they going to find the key?
- 3. How it works
- 4. How it works Original plaintext. Substitute letters with their position in the alphabet. I
- 5. Procedure For example: If the first Sudoku number is 5 then the first Key number will be the 5th text number. There is no number written twice in a Sudoku so there is no order problem Numbers from Sudoku give the order of numbers from text so even if the text had more words only nine numbers would be used
- 6. 9 23 12 19 16 5 9 13 7 + 9 19 12 13 5 16 9 7 23 Key Ciphered Text Password Numbers from Sudoku give the order of numbers from text Final Form:
- 7. Security 9! = 362,880 different keys No brute force One attempt Random password makes the situation harder
- 8. Why it’s good for the situation ● Fast and easy for the nephews ● Low chance of mistakes ● Impossible to solve if you don’t know the key ● Only one attempt before locking
- 9. Nephew A solves the Sudoku – Takes first box up left Nephew B deciphers the text substituting each first letter with the number representing its position in the alphabet They cooperate and use table A to find the correct order of numbers of table B. Procedure
- 10. This presentation is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License Cite as: L. Andreou, A. Furfaro, N. Zikou, The Sudoku Cipher: Secure and Fun, Assignment in the Cryptology Course, Center for Talented Youth, Anatolia College & Johns Hopkins University, Thessaloniki, Greece, 12 July 2016
- 11. Nefeli Zikou is a highschool student (K10 grade) in Alexandroupoli, Greece and a member of the Amateur Astronomy Club of Thrace, Greece. She has attended three Summer Schools in Mathematics (2014-2016, organized by the Hellenic Mathematical Society), a Summer School in Modern Physics (2016, organized by the Hellenic Society of Physics, and a 3 week Residential Summer Program Johns Hopkins Center for Talented Youth, organized in Anatolia College, Thessaloniki, Greece. She has successfully participated in a number of national mathematics and physics contests. Nefeli is a native Greek speaker and holds a Cambridge Certificate of Proficiency in English. Email: nefeliz@live.com Slideshare: http://www.slideshare.net/NefeliZikou
Editor's Notes
- #2: enormous fortune greedy family 2 beloved nephews Newspaper From lawyer take location Instructions were given beforehand
- #4: Solved sudoku from newspaper is 2nd code The first box up left gives order of numders from the first code After the nephews receive the sudoku and the text, they follow the instructions like so: Nephew A solves the sudoku Nephew B deciphers the text substituting each first letter with the number representing its position in the alphabet They cooperate and use table A to find the correct order of numbers of table B They insert the password to open the chest
- #5: Text is 1st code they have the text and they substitute the first letters with the number of their position in the alphabet
- #9: Unbreakable low chance of mistakes only one attempt for the password or it locks Fast and easy for the nephews impossible for the analists. So if you don’t know either you can’t find the correct password. Since the algorithm encodes numbers and not words you can not brute force each permutation to find which is the correct one because the plain text is just random numbers. And since the chest locks after 1 incorrect attempt you can not guess. Moreover, if you know the keys the algorithm becomes very simple and fast, with low probability of making a mistake. So it easy for the nephews to decipher the code but hard for the bad guys.