Two new identity-based threshold ring signature schemes

This paper presents two new identity-based threshold ring signature schemes. With these schemes, any group of t   entities spontaneously conscript arbitrarily n−tn−t entities to generate a publicly verifiable t-out-of-n signature on behalf of the group of n members, yet the actual signers remain anonymous. The schemes are proven to be existentially unforgeable against adaptive chosen message and identity attacks (EUF-IBTRS-CMIA) and unconditional signer ambiguity under the random oracle model.