Ensure that there is no encryption key for the role 0

Author: stanislav-tkach

rust/rbac-registration/src/cardano/cip509/validation.rs

@@ -267,6 +267,15 @@ pub fn validate_role_data(metadata: &Cip509RbacMetadata, report: &ProblemReport)
 fn validate_role_0(
     role: &RoleData, metadata: &Cip509RbacMetadata, context: &str, report: &ProblemReport,
 ) {
+    if role.encryption_key().is_some() {
+        report.invalid_value(
+            "Role 0 encryption key",
+            "<some value>",
+            "The role 0 shouldn't have the encryption key",
+            context,
+        );
+    }
+
     let Some(signing_key) = role.signing_key() else {
         report.missing_field("(Role 0) RoleData::signing_key", context);
         return;