Consider the storage of data in encrypted form in a large database using AES. One record has a size of 16 bytes. Assume that the records are not related to one another.
Which mode would be best suited and why?
We consider known-plaintext attacks on block ciphers by means of an exhaustive key search where the key is k bits long. The block length counts n bits with n > k.
1. How many plaintexts and ciphertexts are needed to successfully break a block cipher running in ECB mode? How many steps are done in the worst case?
2. Assume that the initialization vector IV for running the considered block cipher in CBC mode is known.
How many plaintexts and ciphertexts are now needed to break the cipher by performing an exhaustive key search? How many steps need now maximally be done? Briefly describe the attack.
3. How many plaintexts and ciphertexts are necessary, if you do not know the IV? 4. Is breaking a block cipher in CBC mode by means of an exhaustive key search considerably more difficult than breaking an ECB mode block cipher?
Try it now!
How it works?
Follow these simple steps to get your paper done
Place your order
Fill in the order form and provide all details of your assignment.
Proceed with the payment
Choose the payment system that suits you most.
Receive the final file
Once your paper is ready, we will email it to you.