Final Exam Research Paper Example | Topics and Well Written Essays - 1000 words

Final Exam - Research Paper Example On the other hand, bblowfish is a symmetric block cipher and operates in 64-bit block size and a variable key length - from 32 bits to 448bits with 16-round Feistel cipher and uses large key-dependent S-boxes. Moreover it encrypts data on a 32-bit processor at the rate of 18 clock cycles/byte and can run in less than 5K of memory. It is easy to implement The algorithm used in RC4 initialization phase is a key scheduling algorithm(KSA). This algorithm takes the secret key K of length l as the input and begins with the initialization of the internal state S to set it as identity permutation and then uses the key K to generate a random permutation. Thus the algorithm can be summed up as Upon initialization, the internal state S would be [0 1 2 3 †¦ N-1]. During the next step, the value of j is calculated as j = (j + S[i] + K[i mod l]) mod N. Upon swapping value in S[i] becomes value in S[j] and vice versa. From this, it is clear that, only way to keep the initial permutation state unchanged is to keep the value of i and j equal. In order to do that, the value of k should be chosen in such a way that, whenever j is calculated using this formula, it always needs to be equal to the value of i. Upon investing the formula, if we make the values within the bracket i.e j = (j + S[i] + K[i mod l]) mod N equal to N+ i, then upon Mod the result will be equal to i. Upon analysis, we can say(in this case): j+i+K[i], since the value of j depends on itself which in turn depends on the previous value of S[i] (=i) we can say that j will increment to a minimum value of i+(i-1) (Except for i=0) for each iteration. Hence 2i-1+K = N+i. Assuming N =256, we can say K should be equal to 257-i except for i=0, in which case it can be either 256 or 0 to achieve the desired result. Now K takes: Answer: It is not possible to perform encryption operations in parallel on multiple blocks of plaintext in DES CBC mode because in