In the discussion of subkey generation in CMAC, it states that the block cipher isapplied to the block that consists entirely of 0 bits. The first subkey is derived from theresulting string by a left shift of one bit, and, conditionally, by XORing a constant thatdepends on the block size. The second subkey is derived in the same manner from thefirst subkey.a. What constants are needed for block sizes of 64 and 128 bits?