Cryptography

How do you determine the number of key space? - Correct AnswerRaise 2 to the power of the number of bits in the key space. Ex: 4-bit key space would equal 16. Cryptography provides what four key points? - Correct AnswerConfidentiality, Data Integrity, Authentication, and Non-Repudiation What are some logical operations used in cryptography? - Correct AnswerAND operation, OR operation, Not operation, and Exclusive OR (XOR). What are some general encryption techniques? - Correct AnswerSubstitution, Permutation (Transposition), Hybrid What are some different types of substitution techniques? - Correct AnswerMonoalphabetic, Homophonic, Polygram, Polyalphabetic What are three types of cryptosystems? - Correct AnswerSymmetric (secret key, one-key), Asymmetric (public key, two-key), Hashing (One-way, no encryption) What is the purpose and steps of Digital Signature? - Correct Answer"Digital signatures provide authentication and integrity, which forms nonrepudiation. They do not provide confidentiality: the plaintext remains unencrypted. (1) A plaintext test message is created (2) A hash function generates a hash value of the plaintext. (3) A digital signature by encrypting the hash with his RSA private key. (4) Lastly, the user attaches the signature to their plaintext email and sends. Explain the Kerckhoff's Principle - Correct Answer(1) Cryptosystem should not be secret, (2) The key should be secret, (3) Cipher's should be unbreakable, (4) Keys should be..., (5) What are ways to encrypt data? - Correct AnswerBreak data into Blocks and encrypt each block or Encrypt the entire stream on a bit-by-bit basis What are features of a Stream ciphers? - Correct AnswerStream is encrypted one bit or byte at a time, High speed and low hardware complexity, great for audio, video, & telephone. What are features of a Block ciphers? - Correct AnswerBlock Encrypted a message a block at a time through "Chunking" Identify and explain the Block Cipher Modes - Correct Answer"Electronic Code Block (ECB), Cipher Block Chaining (CBC), Cipher Feedback (CFB), Output Feedback (OFB), and Counter (CTR)" If a symmetric key is encrypted with a receiver's public key, what security service(s) is (are) provided? - Correct AnswerConfidentiality. Only the reciever's private key can be used to decrypt the symmetric key, and only the receiver should have access to this private key. If data is encrypted with the sender's private key, what security service(s) is (are) provided? - Correct AnswerAuthentcity of the sender and nonrepduction. If the reciever can decrypt the encrypted data with the sender's public key, then they know the data was encrypted with the sender's private key. If the sender encrypts data with the receiver's private key, what security services(s) is (are) provided? - Correct AnswerNone. No one but the owner of the private key should have acess to it. (trick question) Why do we encrypt the message with the symmetric key? - Correct AnswerBecause the asymmetric key algorithm is too slow. Why don't we encrypt the symmetric key with another symmetric key? - Correct AnswerThe symmetric key needs to get to destination securely, which can only by carried out through asymmetric cryptography via the use of public and private keys to provide a mechanism for secure transport of symmetric key.