$1.$ A cryptographic strong hash function may be obtained using the following method:

A$.$ Using a CBC mode of a compression function based on a public$-$key encryption algorithm

B$.$ None of the above

C$.$ Using a simple checksum mechanisms for error detection

D$.$ Using a cryptographically strong compression function

E$.$ Using a CBC mode of a compression function based on a strong symmetric$-$key encryption algorithm

$2.$ In the following list of questions regarding authentication, which one is the best answer?

A$.$ Let H be a hash function with output length m$.$ Then the square root of the m$-$th power of $2$ is the upper bound of the cryptographic strength of H becasue of birthday attacks.

B$.$ Hash functions are used in authentication for the purpose of speeding up calculations and reducing network traffic.

C$.$ The strength of SHA$-160$ is at least the $79$th power of

D$.$ All of the above.

E$.$ All of the above except $3.$

F$.$ None of the above.