Paper 2023/423

A Note on Hybrid Signature Schemes

Nina Bindel, SandboxAQ
Britta Hale, Naval Postgraduate School

This draft presents work-in-progress concerning hybrid/composite signature schemes. More concretely, we give several tailored combinations of Fiat-Shamir based signature schemes (such as Dilithium) or Falcon with RSA or DSA. We observe that there are a number of signature hybridization goals, few of which are not achieved through parallel signing or concatenation approaches. These include proof composability (that the post-quantum hybrid signature security can easily be linked to the component algorithms), weak separability, strong separability, backwards compatibility, hybrid generality (i.e., hybrid compositions that can be instantiated with different algorithms once proven to be secure), and simultaneous verification. We do not consider backwards compatibility in this work, but aim in our constructions to show the feasibility of achieving all other properties. As a work-in-progress, the constructions are presented without the accompanying formal security analysis, to be included in an update.

Note: Change log: Revision .v2 adding clarify, further examples, and a section on hybrid and black box scales.

Available format(s)
Public-key cryptography
Publication info
Post-quantum signaturehybrid signature schemescomposite signature schemesdual signatures
Contact author(s)
nina bindel @ sandboxaq com
britta hale @ nps edu
2023-07-22: revised
2023-03-23: received
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Creative Commons Attribution


      author = {Nina Bindel and Britta Hale},
      title = {A Note on Hybrid Signature Schemes},
      howpublished = {Cryptology ePrint Archive, Paper 2023/423},
      year = {2023},
      note = {\url{}},
      url = {}
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