# security of a sponge construction

I don't get why the size of C (the capacity) of a sponge construction influences the security of the sponge construction. And what is the influence of the size of R?

• Possible duplicate of this What is the importance of the rr and cc values for the Sponge Construction? Jan 20 '18 at 14:51
• I'd propose that this question focuses on the second part about $R$. Because I think we would have to close the question as the dupe otherwise. tomak, are you OK with that? Jan 20 '18 at 15:56
• @MaartenBodewes yes ;) Jan 20 '18 at 16:12

The rate refers to the bits that are directly input/output into the permutation. A larger rate provides higher performance: Consider the extreme where the rate is only 1 bit - it would require $n$ invocations of the permutation to digest $n$ bits of data, which would be quite slow.