Unlike a handwritten signature, the credibility and verifiability of an electronic signature or seal declines over time. This is due to the declining security of the algorithms that were used to make them, the expiration date and the availability of the data needed to verify them.
For archiving purposes, it is often necessary to ensure verifiability over several decades. During such a long period, the original algorithms may be broken by attacks on vulnerabilities that were not known at the time of signing / sealing. Furthermore, it is possible to assume a significant increase in computing power, which facilitates the breaking of algorithms by brute force. Therefore, electronic signatures and seals must be maintained during the archiving period, for example by regular archival signing, which overwrites the fingerprints of the original document, the original signature or seal and the valid data needed to verify them at that time. By such re-signing, it is possible to ensure that even after several years, the document with the signature / seal will be verifiable as valid, which allows the document signed in this way to be used for a long time for legal purposes as well.
