John and Anthony are two branch managers of a financial organization. John has a message, M1, to be communicated to Anthony. For a secure communication, John wants to send message M2 to Anthony (without revealing M1 immediately) that can be used later to verify that John knew M1 at the time M2 was sent. During this later verification, John may reveal M1 itself.  

a. Suppose John simply sends M2 = hash(M1). Explain how Anthony can quickly recover M1. 

b. There are some possibilities of attacks when John uses a simple hash function. How can John construct M2 using a secure-hash function, avoiding the problem of those attacks? Hint: as part of the later verification, John can supply additional information to Anthony. 

While working as an IT security manager.

1. Identify and explain the appropriate error control mechanism used, if: 

a. The encoded data has some redundant information for recovering from the errors during communication.  

b. The encoded data has some redundant information for detection of some corrupted blocks which needs to be retransmitted.  

2. Why should you prefix the MIME headers while sending the web pages? 

3. You received complaints from a number of employees that some spam messages are being sent by an employee's computer and you found the complaints correct. What is the reason for this type of attack? 

4. Voice over IP (VOIP) is used by your organization for the teleconferencing system by utilizing the UDP for data transmission. What will happen if the UDP Data grams are out of order?

Answer rating: 100% (QA)

a If John simply sends M2 hashM1 to Anthony its a weak approach for secure communication Anthony can quickly recover M1 by using a precomputed table o... View the full answer