How to embed a digital signature with limited space

I am using RFID tags to store some data that will then be read by a third party user. I need to include a digital signature (or some options) along with the data so that a third party can verify the tag's authenticity.

Simple enough. But the problem is that I am limited by the 32 byte RFID memory array. My application is written in C # (.NET 3.5) and the available digital signature class (DSACryptoServiceProvider) results in a 40 byte signature.

Let's say I need 24 out of 32 bytes to store my data. Is there a way to create an 8 byte signature?

Any insight is greatly appreciated!