With the ECB mode, if there is an error in a block of the transmitted ciphertext, only the corresponding plaintext block is affected. However, in the CBC mode, this error propagates. For example, an error in the transmitted C1 obviously corrupts P1 and P21. 1. Are any blocks beyond P2 affected? 2. Suppose that there is a bit error in the source version of P1. Through how many ciphertext blocks is this error propagated? What is the effect at the receiver? (Encryption algorithms question)

2- If we have an IP packet of size 4000 bytes will be fragmented equally in two (equally )fragments a. the values of M bit of the flag field first fragment b. the values of M bit of the flag field Second fragment C. the values of Offset field on the first fragment. d. the values of Offset field on the Second fragment. e. the Total length field on the first fragment (if max options) f. the Total length field on the first fragment (if no options)

In this problem, we will get practice with computing the one’s complement of the one’s complement sum over a sequence of data values. We will use the exact same algorithm used to compute TCP/UDP checksum, but over a sequence of 4-bit chunks rather than 16-bit chunks. (a) Consider the following data bits. What is the (4-bit) checksum of this (8-bit) data? 0101 1100 (b) Consider the following data bits. What is the 4-bit checksum of this (12-bit) data? (Note: you may be able to reuse calculations from part (a).)  0101 1100 1001

The message to be sent from source to destination is 4000B.  The link MTU's from source to destination are 1500, 1000, and 750. If we  DO NOT use Path MTU, what are the respective fragment sizes to be reassembled? If we DO use Path MTU, what are the respective fragment sizes to be reassembled? Remember, assume that the L3 and L4 headers have length=0.