**(Hierarchical Identity-Based) Threshold Ring Signatures**

*Victor K. Wei and Tsz Hon Yuen*

**Abstract: ** We construct the first several efficient threshold ring signatures (TRS) without random oracles. Specializing to a threshold of one, they are the first several efficient ring signatures without random oracles after the only earlier instantiation of Chow, Liu, Wei, and Yuen. Further specializing to a ring of just one user, they are the short (ordinary) signatures without random oracles summarized in Wei and Yuen.
We also construct the first hierarchical identity-based threshold ring signature without random oracles. The signature size is $O(n\lambda_s)$ bits, where $\lambda_s$ is the security parameter and $n$ is the number of users in the ring. Specializing to a threshold of one, it is the first hierarchical identity-based ring signature without random oracles. Further specializing to a ring of one user, it is the constant-size hierarchical identity-based signature (HIBS) without random oracles in Yuen-Wei - the signature size is $O(\lambda_s)$ bits which is independent of the number of levels in the hierarchy.

**Category / Keywords: **public-key cryptography / ring signature, threshold signature, identity-based signature

**Date: **received 2 Jun 2006

**Contact author: **kwwei at ie cuhk edu hk

**Available format(s): **PDF | BibTeX Citation

**Version: **20060620:075238 (All versions of this report)

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