Crossover under the root of a certification authority

National level Public key infrastructure had faced a set of challenges, one of this is to make decision about which is most appropriate TRUST MODEL to be adopted in Sudan and CAs Interoperability, and This is due to the complexity of the government departments and their continuous changes and restructuring. Also the relative expected traffic between these departments represents another challenge. For example, the Banking system have most of their traffic is between banks. This paper considers these challenges and a solution is proposed to make Interoperability smoother and robust.