In a certain symmetric encryption system E$1$ the secret key $($K$1)$ is used for confidential communication between A and B FFEEDDCCBBAA$9988($hex$)$

A decides to deliver this secret key $($K$1)$ to B by transmitting it over the same insecure channel using a second encryption scheme E$2$

a$-$ What method of encryption would you suggest for E$2?$

b$-$ Based on your suggestion, what would be the size in bits of the key $($K$2)$ used in encryption system E$2?$

c$-$ If a system of computers has the ability to try $128$ keys every $10$ microseconds in an effort to decipher the message encrypted by E$1$ by brute force, how long $($on average$)$ would it take to break the code?

d$-$ Is E$1$ computationally secure$?$