Time stamping is an increasingly valuable complement to digital signing practices, enabling organizations to record when a digital item—such as a message, document, transaction or piece of software—was signed. For some applications, the timing of a digital signature is critical, as in the case of stock trades, lottery ticket issuance and some legal proceedings. Even when time is not intrinsic to the application, time stamping is helpful for record keeping and audit processes, because it provides a mechanism to prove whether the digital certificate was valid at the time it was used. The growing importance of digital signing solutions has created a corresponding demand for time stamping, so many software programs, such as Microsoft Office, support time stamping capabilities. The Importance of Security If time stamping is to add real value, the time stamp must be secure. Risks Associated with Insecure Time Stamping The inability to trust electronic processes can result in costly paper trails to back up electronic records. By manipulating a computer clock, an attacker can easily compromise a software-based time stamping process—thereby invalidating the overall signing process. Insecure time stamping or digital signing processes can expose organizations to compliance problems and legal challenges. Even after private signing keys and certificates have been revoked, users can still have access to them. Without time stamping, organizations cannot prove whether signatures were created before or after a certificate was revoked.