Alice wants to sign some code she has written and then send it to Bob. The diagram below shows the signing process of her code.

a$.$ What type of cryptographic function should be used in block $1?$

b$.$ Provide the name of an algorithm that can be used in block $1$:

c$.$ What type of cryptographic function should be used in block $2?$

d$.$ What does the input to block $2($labeled $"3"$ above$)$ should be$?$

Consider the figure below. In the space provided next to the figure, describe what the figure illustrates. Include details on the cryptographic function likely used in block $1,$ the key employed, as well as a description of what is being achieved.

Consider the figure below. In the space provided next to the figure, describe what the figure illustrates. Include details on the type of crvbtographic function used as well as a description on what security service is being implemented.