Dan Jones is the new CIO of Ricochet Systems, an Internet securities broker. After assessing the e-commerce risks in his company, he determines that passwords are a weak link that need additional protection. At your monthly golf outing, Dan asks youknowing your background in computer forensicswhat checks and policies should be in place on passwords in his company. You tell Dan that while passwords are a vital part of the security of any electronic system, other, more secure, alternatives also are available for providing authorization of transactions and activities.

Which of these methods of providing authorization reassures users that transactions are valid?

a. Firewalls

b. Digital signatures and certificates

c. Biometrics

d. Encryption