1. You are working for a company that provides security recommendations for a number of IT firms, each with different requirements and goals. For each of the following scenarios, give the transmission mode you would recommend or sending information, and why you would do so.
   1. Company A sends messages in blocks (that is, no streaming). These messages are very large, containing many repeated blocks. Speed of encryption/decryption is not a concern. They are willing to generate and send a new key for each message if necessary.
   2. Company G streams messages over a network. They are willing to generate and exchange a new key each time. To save time during encryption, they would like to have the ability to generate the entire key stream in advance (that is, before the actual message to be encrypted is known).
   3. Company C sends message in blocks (that is, no streaming). These messages are very short, consisting of few blocks, and are not sent very often. They also have parallel hardware that they would like to take advantage of in order to speed up the encryption/decryption process. They would like to avoid having to generate and exchange new keys for each message.
   4. Company D streams messages over a network. These messages are generally long and sent very often. They will not generate new keys for each message. They also have parallel hardware they would like to take advantage of, but are willing to sacrifice that speed for better security.