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Pavel,
I personally have some sympathy for your view. I will add this issue to those for discussion at the next ETSI meeting later in June.
Nick
-----Original Message-----
Hello all and personally Nick,
In current CAdES wording a regular signature without at least one signed attribute (Signing certificate reference) cannot be added with timestamps and validation data to achieve CAdES-T or more advanced CAdES signature. This need arises, e.g., in a system with existing regular signatures. There is no chance to add the required attribute to the already computed signature, but there is a strong need to add CAdES properties to such signatures.
There is rather simple approach to achieve the same properties without including signing certificate reference as a signed attribute. Let us include this reference as an extension in the CAdES-T timestamp (signature timestamp). To get such timestamp one would need to include this extension in a timestamp request and a TSA would have to shift this extension to a timestamp token.
Let us define the proposed extension to a timestamp protocol and call the signature we get a valid CAdES-T signature. More advanced CAdES signature types turn out from this new CAdES-T perfectly without any modification. What do you think?
Pavel Smirnov Crypto-Pro
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