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At least one of the answers above is NOT correct.

$(1$ point$)$ This question concerns block cipher modes. We will use a simple affine cipher, which can be expressed in $C$ as follows.

char cipher$($unsigned char block, char key$)$

i

return $($key$+11$"block$)\%256$;

$\}$

Note that the block size is $8$ bits, which is one byte $($and one ASCII character$).$ We will work with the fixed key $0$x$08.$

is a $3$ bit counter that begins at $0.$ In all of the problems given below, one character is one block. Each character of the plaintext should be regarded as its corresponding ASCII code.

a$)$ Encrypt the plaintext "happy" using CTR mode. Please enter your answer in hex. $($Please do "not" enter an $0$x$,$ as this has been done.$)$

$0$

b$)$ Encrypt the plaintext $"$ frogs" using ECB mode. Please enter your answer in hex.

c$)$ Encrypt the plaintext "sitting" using CF B mode. Please enter your answer in hex.

$0x$

d$)$ Encrypt the plaintext "crisscross" using CBC mode. Please enter your answer in hex.

$0x$

e$)$ Encrypt the plaintext "style" using OFB mode. Please enter your answer in hex.

$0x$