Design Recipes for FPGAs
126
• Compute round constant r(i) 00000010 (i 4)/4 in
GF(2
8
).
•
If i is not a multiple of 4,
•
Implementing AES in VHDL
We have two options for implementing block cipher operations in
VHDL. We can use the structural approach (shown in the DES
example previously in this chapter), or sometimes it makes sense
to define a library of functions and use those to make much sim-
pler models.
In the AES example, we can define a top level entity and archi-
tecture that has the bare minimum of structure and is completely
defined using functions. This can be especially useful when work-
ing with behavioral synthesis software as this allows complete ...