Initialize the security_content_manager and SecurityContentService in simulator

[holgerroth]

This would help in experimenting with homomorphic encryption in simulation mode. Thanks @shawndengucf for raising the issue and providing a workaround.

Based on previous issue #1924. See also #1994

Thanks, @holgerroth ! It's really helpful. I created the secure_workspace and copied the whole folder to my project folder and specified the tenseal_context_file for HEModelEncryptor. However, the error persisted and I noticed that SecurityContentService doesn't get a chance to initial the security_content_manager if I submit the job with the simulator, see load_tenseal_context_from_workspace from homomorphic_encrypt.py.

I made it work by editing the function to below:

def load_tenseal_context_from_workspace(ctx_file_name: str, fl_ctx: FLContext):
    """Loads homomorphic encryption (HE) context from TenSEAL (https://github.com/OpenMined/TenSEAL) containing encryption keys and parameters.

    Args:
        ctx_file_name: filepath of TensSEAL context file
        fl_ctx: FL context

    Returns:
        TenSEAL context

    """
    is_secure_mode = fl_ctx.get_prop(FLContextKey.SECURE_MODE, True)
    if ctx_file_name != "client_context.tenseal":
        ssc = SecurityContentService()
        ssc.initialize(os.path.dirname(ctx_file_name))
        data, rc = ssc.load_content(ctx_file_name)
    else:
        data, rc = SecurityContentService.load_content(ctx_file_name)

    bad_rcs = [LoadResult.INVALID_CONTENT, LoadResult.NO_SUCH_CONTENT]
    if is_secure_mode:
        bad_rcs.extend([LoadResult.INVALID_SIGNATURE, LoadResult.NOT_SIGNED])

    if rc in bad_rcs:
        raise ValueError("Cannot load tenseal_context {}: {}".format(ctx_file_name, rc))

    context = ts.context_from(data)
    return context

Originally posted by @shawndengucf in #1924 (comment)

[chesterxgchen]

This is caused by "Unknown type tenseal.tensors.ckksvector.CKKSVector, ..."
which means FOBs doesn't know how serialize the object CKKSVector. If you define a decomposer for FOBs, and register the decomposer, then the serialization should pass.

[holgerroth]

@chesterxgchen , This issue is only about the secure content manager when running HE in simulation. The serialization error is discussed in this issue #1924.

[holgerroth]

Note the related issue at #1970