Add identity verifications to non-identity-based entity authentication factories

[wmiaw]

There are a few entity authentication factories that do not authenticate based on the entity identity directly, but instead based on some other value. For example RSA which uses a pubkeyid separate from the identity value.

To ensure that the identity cannot be spoofed, it is important for the entity authentication factory to ensure only specific identities can use specific keys. Modify the example code so it does this.