Cryptology ePrint Archive: Report 2018/970

Protean Signature Schemes

Stephan Krenn and Henrich C. Pöhls and Kai Samelin and Daniel Slamanig

Abstract: We introduce the notion of Protean Signature schemes. This novel type of signature scheme allows to remove and edit signer-chosen parts of signed messages by a semi-trusted third party simultaneously. In existing work, one is either allowed to remove or edit parts of signed messages, but not both at the same time. Which and how parts of the signed messages can be modified is chosen by the signer. Thus, our new primitive generalizes both redactable (Steinfeld et al., ICISC '01, Johnson et al., CT-RSA '02 & Brzuska et al., ACNS'10) and sanitizable signatures schemes (Ateniese et al., ESORICS '05 & Brzuska et al., PKC'09). We showcase a scenario where either primitive alone is not sufficient. Our provably secure construction (offering both strong notions of transparency and invisibility) makes only black-box access to sanitizable and redactable signature schemes, which can be considered standard tools nowadays. Finally, we have implemented our scheme; Our evaluation shows that the performance is reasonable.

Category / Keywords: public-key cryptography /

Original Publication (with major differences): CANS 2018

Date: received 11 Oct 2018

Contact author: kaispapers at gmail com

Available format(s): PDF | BibTeX Citation

Note: Contains additional definitions and all proofs.

Version: 20181015:120833 (All versions of this report)

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