Function parse_encrypted_data_template_node_with_policy 

pub fn parse_encrypted_data_template_node_with_policy(
    node: Node<'_, '_>,
    policy: &EncryptionPolicy,
) -> Result<EncryptedData, XmlEncError>

Parse an xenc:EncryptedData template under an immutable policy snapshot.

This applies the complete encrypted-data grammar and metadata limits while permitting empty CipherValue placeholders that encryption will replace. Non-empty placeholders must still be well-formed base64. The containing source document is reparsed under this policy before template inspection.