Recommendations for QS Signature Solutions

This report aims at offering advice in finding suitable post-quantum secure digital signature solutions. As the choice of a suitable solution is dependent on the intended application, it is not possible to make a universal recommendation; rather, we offer guidance by means of information. To this end, we provide an overview of the available post-quantum signature schemes that may be considered for replacing current non-quantum-secure solutions. We elaborate on their respective characteristics and their respective advantages and disadvantages. Furthermore, we discuss approaches for hybrid solutions, which combine post-quantum and conventional signature schemes via cryptographic combiners and so offer security even if one of the two component schemes gets broken. We point out the advantages and disadvantages of using such a hybrid solution, and we elaborate on certain features that in the literature are sometimes promoted as being desirable.