Cryptography Final Exam Questions And Answers With Complete Solution

Hybrid encryption: What is hybrid encryption? Why do we need it? {Ans: Hybrid encryption is a mode of encryption that merges two or more encryption systems. It incorporates a combination of asymmetric and symmetric encryption to benefit from the strengths of each form of encryption. These strengths are respectively defined as speed and security}Digital certificate: Is there any secret information stored in a digital certificate? Should we keep digital certificate secret? {Ans: No private information is found in a cert, they should not be kept secret. In fact, they can be posted on the internet for others to use if needed.}How does DES work? The details of DES encryption, decryption, and key scheduling? What are DES's key size, data block size, and number of rounds? How secure is it? {Ans: Key size: 56 bites Plaintext size: 64 bits 16 Rounds 64 bit plaintext passes through initial permutation that rearranges the bits to produce permutated input. Then 16 rounds of the same function with permutations and substitutions. The output of the last round has 64 bits that area function of the input plaintext and the key. The left and right halves of the output are swapped to produce