"Functional signatures: new definition and constructions" by Qingwen Guo, Qiong Huang et al.
Functional signatures (FS) enable a master authority to delegate its signing privilege to an assistant. Concretely, the master authority uses its secret key skF to issue a signing key skf for a designated function f∈ ℱFS and sends both f and skf to the assistant ℰ, which is then able to compute a signature σf with respect to pkF for a message y in the range of f. In this paper, we modify the syntax of FS slightly to support the application scenario where a certificate of authorization is necessary. Compared with the original FS, our definition requires that ℱFS is an injective functio...
Source: uow.edu.au