The timestamping service (TS) is the service provided by a CA that provides a certificate with the date, time and a signature of the CA, stating that certain digital data existed at a certain point in time. The SwissSign timestamping service complies with Swiss law (ZertES).

Digital timestamps are mainly used for archiving documents with precise timing or for labelling business documents such as contracts. Furthermore, Swiss law stipulates that a qualified signature is only equivalent to a handwritten signature if it is accompanied by a ‘qualified’ timestamp. The SwissSign timestamps can be used for workflow and archiving solutions. Although each electronic signature already contains a time (local system time), it can be useful to include an externally authenticated time with the data and documents. This makes it possible to easily and transparently prove at any time that the corresponding data record existed at a certain point in time and has not been changed since the exact time of stamping (integrity).

Usage: for example, in solutions for the implementation of legal requirements such as the Swiss Business Records Ordinance (AccO/GebüV), compliance regulations such as SOX, Basel II or industry-specific quality frameworks such as GMP.

The timestamp is technically a signature of the provider that contains a trustworthy time. This timestamp is generated through the Timestamping Authority (TSA) in accordance with RFC 3161. The RFC 3161 protocol requires that the request contain the hash value, which is then signed by the TSA. This ensures that the TSA service does not know anything about the content of the timestamped documents.

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The reason for this is the adaptation of the timestamping service to the new security requirements and the resulting increase in the size of the response to the Adobe program by a few bytes. Adobe is not equipped for this in its normal configuration, so it recommends increasing the iSize in the registry.

The following patch for Adobe Reader DC serves as an example. Please save the following text as the file ‘fix_adobe.reg’ and double-click to make the change to the registry. It is advisable to back up the registry beforehand. Remember that the registry file is always specific to the Adobe version and, therefore, the text may need to be modified. E.g. may the part below that reads «Adobe Reader» be replaced by «Adobe Acrobat».

For Adobe Reader:

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\DC\Security\cASPKI\cAdobe_TSPProvider]

"iSize"=dword:00002800

For Adobe Acrobat Pro:

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Adobe\Adobe Acrobat\DC\Security\cASPKI\cAdobe_TSPProvider]

"iSize"=dword:00002800