For the ECB, CBC, and CFB modes, the plaintext must be a sequence of one or more complete data blocks (or, for CFB mode, data segments). In other words, for these three modes, the total number of bits in the plaintext must be a positive multiple of the block (or segment) size. One common method of padding, if needed, consists of a 1 bit followed by as few zero bits, possibly none, as are necessary to complete the final block. It is considered good practice for the sender to pad every message, including messages in which the final message block is already complete. What is the motivation for including a padding block when padding is not needed

Usually, when we sniff packets, we are only interested certain types of packets. we can do that by setting filters in sniffing. scapy’s filter use the bpf (berkeley packet filter) syntax; you can find the bpf manual from the internet. set the following filters and demonstrate your sniffer program again (each filter should be set separately): (a) capture only the icmp packet. (b) capture any tcp packet that comes from a particular ip and with a destination port number 23. (c) capture packets comes from or to go to a particular subnet. you can pick any subnet, such as 128.230.0.0/16; you should not pick the subnet that your vm is attached to.

Least square fit to polynomial write a function leastsquarefit3pol that solves a linear system of equations to find a least squares fit of a third order polynomial to an experimental data set given as two row arrays. the function leastsquarefit3pol must explicitly solve a set of linear equations and cannot use polyfit. there should be no restriction on the size of the problem that can be solved.

Which of the following calculates the total from the adjacent cell through the first nonnumeric cell by default, using the sum function in its formula? -average -autosum -counta -max