ECDSA signature verifiable 1-way transformations
Use a zero-knowledge proof of knowledge (ZKPoK) of a value $(r,s)$ that is a valid signature.  For instance, you might be able to adapt existing ZKPoKs for proof of knowledge of a discrete logarithm to this problem.  Because it is zero-knowledge, you will know that it reveals nothing about $(r,s)$ and is not transferable.