  Ring signatures enable a user to sign messages on behalf of an arbitrary set
of users, called the ring, without revealing exactly which member of that ring
actually generated the signature. The signer-anonymity property makes ring
signatures have been an active research topic. Recently, Park and Sealfon
(CRYPTO 19) presented an important anonymity notion named signer-unclaimability
and constructed a lattice-based ring signature scheme with unclaimable
anonymity in the standard model, however, it did not consider the unforgeable
w.r.t. adversarially-chosen-key attack (the public key ring of a signature may
contain keys created by an adversary) and the signature size grows
quadratically in the size of ring and message. In this work, we propose a new
lattice-based ring signature scheme with unclaimable anonymity in the standard
model. In particular, our work improves the security and efficiency of Park and
Sealfons work, which is unforgeable w.r.t. adversarially-chosen-key attack, and
the ring signature size grows linearly in the ring size.
