The PDF digital signatures generated by Aspose.Words is hard coded to always use a specific hashing algorithm out of the SHA2 family, namely: SHA512.
Please add an option so the hashing algorithm to be used can be set via the API:
This could be done for example by adding a property named ‘HashingAlgorithm’ which is of an enum type containing at least the following declared values: SHA1, SHA256, SHA384, SHA512.
The default could still be SHA512 to be backwards compatible.
Why is this important:
Aspose.Words for .Net currently uses the functionality provided by the .Net API to perform the cryptographic processing like calculation of the hash used in the PDF digital signature and the .Net framework on its turn uses the Crypto API provided by the windows OS, which on Windows XP does not support any of the SHA2 family hashing algorithms.
Thus: Currently generating digital signatures for PDF documents with Aspose.Words for .Net on Windows XP results in an exception being thrown.