A threshold attribute-based signature (t-ABS) scheme defines each signer with a set of attributes

which determine signature ability for each signer.In a t-ABS

signature holder prove possession of signatures by revealing only a threshold number of attributes in common with the verification attribute set

hence providing signer-attribute privacy for the signers.In this paper

we analyze a flexiblethreshold ABS proposed by Li et al and demonstrate its vulnerability to forgeable attacks.Finally

we introduce a t-ABS scheme

which is proved to be secure in the standard model based on CDH problem.