For further information on certificate security and practices, see [RFC 5280
], especially the Security Considerations section.
Since non-critical certificate extensions are ignored by implementations that do not recognize the extension object identifier (OID), constraints on PASSporT validation will only be applied by relying parties that recognize the EnhancedJWTClaimConstraints extension.
The Enhanced JWT Claim Constraints certificate extension can be used by certificate issuers to provide limits on the acceptable PASSporTs that can be accepted by verification services. Enforcement of these limits depends upon proper implementation by the verification services. The digital signature on the PASSporT data structure will be valid even if the limits are violated.
Use of the Enhanced JWT Claim Constraints certificate extension permittedValues constraint is most useful when the claim definition allows a specified set of values. In this way, all of the values that are not listed in the JWTClaimValuesList are prohibited in a valid PASSporT.
Certificate issuers must take care when imposing constraints on the PASSporT claims and the claim values that can be successfully validated; some combinations can prevent any PASSporT from being successfully validated by the certificate. For example, an entry in mustInclude and an entry in mustExclude for the same claim will prevent successful validation on any PASSporT.
Certificate issuers SHOULD NOT
include an entry in mustExclude for the "rcdi" claim for a certificate that will be used with the PASSporT Extension for Rich Call Data defined in [STIR-PASSPORT-RCD
]. Excluding this claim would prevent the integrity protection mechanism from working properly.
Certificate issuers must take care when performing certificate renewal [RFC 4949
] to include exactly the same Enhanced JWT Claim Constraints certificate extension in the new certificate as the old one. Renewal usually takes place before the old certificate expires, so there is a period of time where both the new certificate and the old certificate are valid. If different constraints appear in the two certificates with the same public key, some PASSporTs might be valid when one certificate is used and invalid when the other one is used.