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calculate a tag of CBC-MAC

in flag

with a block cipher having a 256-bit key and 128-bit block length to MAC a 1024-bit message. How many evaluations of the block cipher will be performed to calculate the tag? [Assume there is no padding]

i am assuming that in order to get the number blocks we need i have to divide 1024 by 128 where i get 8 blocks. so does the answer should be 8 evaluations of blocks? i just want to make sure that i am on the right track.

poncho avatar
my flag
"Assume there is no padding" - unless we're guaranteed that the message will be a multiple of the block length (e.g. a multiple of 16 bytes long), we always add padding; otherwise, the attacker can easily find pairs of messages that will always have the same MAC.
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