Blind Threshold Signatures Based on Discrete Logarithm

In this paper, we propose two group-oriented (t, n) blind threshold signature schemes based on the discrete logarithm problem. By these schemes, any t out of n signers in a group can represent the group to sign blind threshold signatures. In our schemes, the size of a threshold signature is the same as the size of an individual signature and the signature verification process is simplified by means of a group public key. Our proposed schemes do not require the assistance of a mutually trusted authority. In addition each signer can select his own private key and the group public key is determined by all the members. The security of our schemes rely on the difficulty of computing discrete logarithm.