Can someone clarify what is meant by the terms cryptosystem bandwidth and block size for public key cryptosystems; The context is the Paillier cryptosystem and its Damgard-Jurik generalisation. My intuition is that they refer to the modulus. Since the modulus is $n^2$ and $n^s$ respectively does it apply that they have more bandwidth/block size than ElGamal which computes $mod \;\; q$; Is this intuition correct;
Let $c$ denote a ciphertext and let $m$ denote a plaintext. To my best knowledge, researchers in cryptography employ "bandwidth" as different meanings, say, ciphertext expansion ($|c|/|m|$) or a number of bits of plaintexts contained in a ciphertext ($|m|$). @owlstead refers "overhead," which is $|c| - |m|$. For example,
I think you mean the latter, i.e., $|m|$ and "block size" seems to be $|c|$.
Let us calculate $|m|/|c|$.