I was wondering in the Chaskey, when the message
m is split into fixed size blocks such as
m1,m2,m3....ml, what would be the size of each message block?
Is it 128 bits each or it can be of any variable size?
Looking at the original paper, the block sizes can be anything but all blocks except for last have to be of same size.
3.1 Mode of Operation
Chaskey uses an n-bit key K to process a message m of arbitrary size into a tag τ of t ≤ n bits.
For every key K, two subkeys K1, K2 are generated as shown in Algorithm 2. The message m is split into ℓ blocks m1, m2, . . . , mℓ of n bits each, except for the lastblock mℓ which may be incomplete.
But according to the author it is specially designed for 128 bit security so my guess is that it is better to use 128 bit keys.