Authors : Mohammad Jawad Kadhim Abood, Faez Al-Maamori and Wadhah R. Baiee
Abstract: Initialization vector or starting variable is an arbitrary number employed only one time in any session. It can be used along with a secret key for data encryption in several modes in order to randomize the encryption to produce distinct cipher texts even if encrypting the same plaintext several times, so no need to the process of slower re-keying. The IV is nothing more than a fixed-size number that used for data encryption along with a key. Unlike the key, the secrecy of IV (initialization vector) is not usually required. Because of that, reusing the IV destroy the security. In OFB and CTR modes create a bit-stream depend on the password and IV only. In the other hand, the IV in CBC mode must be unpredictable at the time when it is encrypted. An initialization vector has different security requirements than a key, so, the IV usually does not need to be secret. Therefore, OFB and CTR, reusing an IV completely destroys security. This can be seen because both modes effectively create a bitstream dependent on the password and IV only. In CBC mode, the IV must in addition be unpredictable at encryption time because if the man in the middle know the IV he can check his guess in the plain text of some blocks that was use the same key to encrypted. The main attention in this article is how could make the probability of predicting the IV closed enough to zero value. On the other sence: How could make picking up the IV is impossible unless knowing the mathematical approach which used of building the IV.
Mohammad Jawad Kadhim Abood, Faez Al-Maamori and Wadhah R. Baiee, 2018. Decrees the Possibility of Predicting Initialization Vector by Using Mathematical Methods. Journal of Engineering and Applied Sciences, 13: 4774-4777.