Computation environments are protected from bogus or rogue load modules,
executables, and other data elements through use of digital signatures,
seals, and certificates issued by a verifying authority. A verifying
authority--which may be a trusted independent third party--tests the load
modules and/or other items to verify that their corresponding
specifications are accurate and complete, and then digitally signs them
based on a tamper resistance work factor classification. Secure
computation environments with different tamper resistance work factors
use different digital signature authentication techniques (e.g.,
different signature algorithms and/or signature verification keys),
allowing one tamper resistance work factor environment to protect itself
against load modules from another tamper resistance work factor
environment. The verifying authority can provide an application intended
for insecure environments with a credential having multiple elements
covering different parts of the application. To verify the application, a
trusted element can issue challenges based on different parts of the
authenticated credential that the trusted element selects in an
unpredictable (e.g., random) way, and deny service (or take other
appropriate action) if the responses do not match the authenticated
credential.