PROPOSED THRESHOLD BLIND SIGNATURE SCHEME SUPPORTING FORWARD SECURITY OF USER KEYS
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Abstract
In this paper, we propose a new type of signature scheme called the Forward-Secure Threshold Blind Signature (abbreviated as FSTBS), which integrates forward security into a threshold blind signature scheme to enhance protection against secret key exposure attacks. The forward-security property ensures that even if the secret key at the current epoch is compromised, all signatures generated in previous epochs remain intact and cannot be forged retroactively. We achieve this forward-security property through a key-update mechanism across epochs (time periods), in which all participating signers can securely and synchronously update their secret keys. To illustrate the proposed scheme, we construct a concrete FSTBS instance based on the Snowblind threshold blind signature (by Elizabeth Crites et al., presented at CRYPTO 2023). The proposed FSTBS retains Snowblind’s advantages in signing efficiency, signature size, and its underlying security properties, while additionally incorporating forward security. However, this integration introduces some additional computational cost compared to Snowblind, particularly in the key generation and key update phases.
Keywords
Blind signature, Threshold blind signature, Snowblind, Forward-Secure
Article Details
References
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