You're generating a bundle, it will only generate a complete bundle. It expects both 1024-bit and 2048-bit CSRs. The SDK also expects a certificate bundle to work properly. The SDK will use the 2048-bit certificate whenever possible; however the 1024-bit certificate is still needed to support legacy devices. By the way, your FPS certificate's key size is not really as important as you might think. It mostly serves to identify your server as a FPS content provider. The content stays secure as long as you keep your provisioning_data file (or previously, your ASk) secure.