The constant corresponding to the C identifier xmlSecOpenSSLTransformRsaPssSha256Id is not exposed in xmlsec.constants in the current Python bindings.
This prevents the use of the RSA-PSS/SHA256 signature algorithm when using high-level utility functions like xmlsec.template.create(), which strictly require a __Transform object instead of a URI string.
To properly expose this constant, the following line should be added to the src/xmlsec/constants.c file within the transforms block, following the pattern of other transforms:
PYXMLSEC_ADD_TRANSFORM_CONSTANT(OpenSSLTransformRsaPssSha256, "RSA_PSS_SHA256");
This change enables users with the compiled binding to utilize:
from xmlsec.constants import OpenSSLTransformRsaPssSha256