Patent ID: 9225746
Filing Date: 2015-12-29
Classification: H04L

Abstract:
1. A computer-implemented method, comprising: maintaining, at a cryptographic service provider (CSP), two or more timestamp policies specifying when digital timestamps should be issued, each of the two or more timestamp policies being associated with one or more signing keys; receiving, at the CSP, a timestamp request transmitted from an untrusted timestamp authority that manages timestamping, the untrusted timestamp authority having a lower assurance than the CSP, and the timestamp request being accompanied by a first timestamp data structure from the untrusted timestamp authority and referencing a first timestamp policy of the two or more timestamp policies; determining, with a computer processor, a difference between a first time specified by the untrusted timestamp authority in the first timestamp data structure and a second time indicated by an internal clock of the CSP; rejecting the timestamp request if the first timestamp data structure fails to comply with the first timestamp policy, wherein the first timestamp policy requires at least that the difference between the first time and the second time be below a predetermined threshold; and signing the first data structure with a first signing key, of the one or more signing keys associated with the first timestamp policy, if the first timestamp data structure complies with the first timestamp policy.