To operate successfully, a product sometimes has to implicitly trust the integrity of an information source. When information is implicitly signed, one can ensure that the data was not tampered in transit. This does not ensure that the information source was not compromised when responding to a request.

By requesting information from multiple sources, one can check if all of the data is the same. If they are not, the system should report the information sources that respond with a different or minority value as potentially compromised. If there are not enough answers to provide a majority or plurality of responses, the system should report all of the sources as potentially compromised.

As the seriousness of the impact of incorrect integrity increases, so should the number of independent information sources that would need to be queried.