In a proxy signature scheme, an original signer is allowed to delegate his signing power to a designated person, called the proxy signer and the proxy signer is able to sign the messages on behalf of the original signer. Recently, Lu, Dong and Cao proposed two proxy signature schemes for mobile communication (see Sci China Ser F-Inf Sci, 2008, 51(2): 183-195). Although they proved that their schemes are secure in the random oracle model, we disprove their claim and show that their schemes are not secure.
All Science Journal Classification (ASJC) codes
- Computer Science(all)