Which of the following is the PRIMARY advantage of using secret key encryption systems compared to public key systems? 4. (a) Fast encryption (b) Long keys (c) Easy key management (d) Implemented both in hardware and software 5. In the the encryption of each 8-byte block is independent of the others. (a) OFB mode (b) ECB mode (c) CBC mode (d) CFB mode Which of the following public key encryption and digital signature schemes is most similar to the Diffie Hellman protocol? 6. (a) RSA signature (b) RSA encryption (c) EIGamal encryption (d) ElGamal signature