Cryptanalysis for Additive Cipher || Lesson 7 || Cryptography || Learning Monkey ||

Cryptanalysis for Additive Cipher In this class, We discuss Cryptanalysis for Additive Cipher. The reader should have prior knowledge of crypt analysis attacks. Click Here. Brute force method: We need to try all the possible keys in the brute force method. The total possible keys are from 0 to 25. The key domain is very small, so the brute force method is possible in additive cipher. Example: Identified cipher text: uvaclyfzljbyl Take Key = 1 The first character is "u." The value of "u" is 20. (20 – 1) mod 26 = 19 = t. Like the above, convert all the characters. The plain text for key = 1 is “tuzbkxeykiaxk” Similarly, do this for all the keys. At key = 7, we got the plain text P: not very secure The key value is 7. Statistical Attack: Identified Cipher text C = “xlilsywimwrsajsvwepijsvjsyvqmppmsrsppevwmxmwasvxlqsvilyvvcfijsvixliwippivvigimziwqsvisjjivw” The above cipher text i repeated 14 times. The highest frequency character is i. We assume i as e To convert i to e, we need key value 4. i = 9, so (9 – 4) mod 26 = 5 = e. By using the key value 4 we get the below plain text. The house is now for sale for four million dollars. It is worth more hurry before the seller receives more offers. Link for playlists: https://www.youtube.com/channel/UCl8x4Pn9Mnh_C1fue-Yndig/playlists Link for our website: https://learningmonkey.in Follow us on Facebook @ https://www.facebook.com/learningmonkey Follow us on Instagram @ https://www.instagram.com/learningmonkey1/ Follow us on Twitter @ https://twitter.com/_learningmonkey Mail us @ learningmonkey01@gmail.com