Tireco is a medium-sized firm that manufactures and distributes specialty tires. The company has good separation of duties, and at the top of the organization chart is the president, controller, vice president of manufacturing, vice president of marketing, and the finance officer. Under the vice president of manufacturing are four departments.

The company has decided to do all its business over the Internet using a whole array of commerce servers, each with a JAVA or CGI interface to the central accounting system. The commerce servers are set up to process secure EDI-based orders with customers and vendors.

The president, a recent accounting graduate, has insisted that the company use digital certificates in all its transactions. Furthermore, the company has informed all its vendors that it will not be responsible for the payment of any invoices, electronic or paper, that are not supported by a digital certificate issued by Tireco.

Required 

Assuming that Tireco elects to use public-key encryption, design a system for managing the company's keys and digital certificates. Your design should consider at least the following:

(a) the number of keys that will be needed, and the number of departments that will need them.

(b) who will issue keys.

(c) the expiration dates to be used for keys.

(d) who will have the authority to issue digital certificates.

(e) the structure of the company s certificate chains.

(f) the security measures that will need to be adopted.