The UStG no longer refers to a technology under a specific law, but is formulated in an open manner. The eIDAS Regulation only applies to matters relating to Union law, not to purely domestic matters. The latter are no longer regulated in a uniform manner following the repeal of the SigG,
but result from various other laws (e.g., De-Mail Act). The same principles apply to these regulations: A qualified electronic signature must be based on a qualified certificate that is valid at the time it is generated and must be generated using a secure signature creation device.
Source: bundesfinanzministerium.de
