Surely. The constant words - i.e. words 0-3 are magic numbers that correspond to the byte string expand 32-byte k. You can change 32 to 16, although nobody gave formal definition for 24, which means there can be interoperability problems.

Surely. The constant words - i.e. words 0-3 are magic numbers that correspond to the byte string expand 32-byte k. You can change 32 to 16 and repeat the 128-bit key twice, although nobody gave formal definition for 24, which means there can be interoperability problems.