The integrity of information, people, systems, and devices is
verified. Examples include detailed analysis of code, change detection with
cryptographic checksums, in-depth testing, syntax and consistency
verification, and verification of information through independent means.
Complexity: In general, the integrity checking problem can be quite complex,
however, there are many useful systems that are quite efficient and cost
effective. There is no limit to the extent to which integrity can be
checked and the question of how certain we are based on which checks we have
done is open. As an apparently fundamental limitation, information used to
differentiate between two otherwise equivalent things can only be verified
by independent means.