1. Confidentiality, Integrity and Non-repudiation are all achieved best by which of the following encryption methods? (a) Steganography (b) Combination of Symmetric & Asymmetric (c) Asymmetric Cryptography (d) Hashing and Cryptography 2. If 8 people are involved in symmetric encryption among themselves, the number of keys you need is what? (a) 30 (b) 28 (c) 24 (d) None of the above 3. A digital signature is produced by the following procedure: (a) Hash the message M and encrypt it with recipient's private key (b) Hash the message M and encrypt it with sender's private key (e) Hash the message M and encrypt it with recipient's public key (d) Hash the message Mand encrypt it with sender's public key 4. In the the encryption of each 8-byte block is independent of the others. (a) CFB mode (b) ECB mode (c) CBC mode (d) OFB mode 5. Which of these is NOT true for an ECB? (a) It is ideally suited to be used with small block sizes (b) Every plaintext has a defined corresponding cipher text (c) It can support a different key for every block type (d) Specific plaintext always generates the same cipher text every time