##### 7.1.2.2.3 Cross-Certified Subordinate CA Extensions | __Extension__ | __Presence__ | __Critical__ | __Description__ | | ---- | - | - | ----- | | `authorityKeyIdentifier` | MUST | N | See [Section 7.1.2.11.1](#712111-authority-key-identifier) | | `basicConstraints` | MUST | Y | See [Section 7.1.2.10.4](#712104-ca-certificate-basic-constraints) | | `certificatePolicies` | MUST | N | See [Section 7.1.2.10.5](#712105-ca-certificate-certificate-policies) | | `crlDistributionPoints` | MUST | N | See [Section 7.1.2.11.2](#712112-crl-distribution-points) | | `keyUsage` | MUST | Y | See [Section 7.1.2.10.7](#712107-ca-certificate-key-usage) | | `subjectKeyIdentifier` | MUST | N | See [Section 7.1.2.11.4](#712114-subject-key-identifier) | | `authorityInformationAccess` | SHOULD | N | See [Section 7.1.2.10.3](#712103-ca-certificate-authority-information-access) | | `nameConstraints` | MAY | \*[^name_constraints] | See [Section 7.1.2.10.8](#712108-ca-certificate-name-constraints) | | Signed Certificate Timestamp List | MAY | N | See [Section 7.1.2.11.3](#712113-signed-certificate-timestamp-list) | | Any other extension | NOT RECOMMENDED | - | See [Section 7.1.2.11.5](#712115-other-extensions) | In addition to the above, extKeyUsage extension requirements vary based on the relationship between the Issuer and Subject organizations represented in the Cross-Certificate. The extKeyUsage extension MAY be "unrestricted" as described in the following table if: - the organizationName represented in the Issuer and Subject names of the corresponding certificate are either: - the same, or - the organizationName represented in the Subject name is an affiliate of the organizationName represented in the Issuer name - the corresponding CA represented by the Subject of the Cross-Certificate is operated by the same organization as the Issuing CA or an Affiliate of the Issuing CA organization. Table: Cross-Certified Subordinate CA with Unrestricted EKU | __Extension__ | __Presence__ | __Critical__ | __Description__ | | ---- | - | - | ----- | | `extKeyUsage` | SHOULD[^eku_ca] | N | See [Section 7.1.2.2.4](#71224-cross-certified-subordinate-ca-extended-key-usage---unrestricted) | In all other cases, the extKeyUsage extension MUST be "restricted" as described in the following table: Table: Cross-Certified Subordinate CA with Restricted EKU | __Extension__ | __Presence__ | __Critical__ | __Description__ | | ---- | - | - | ----- | | `extKeyUsage` | MUST[^eku_ca] | N | See [Section 7.1.2.2.5](#71225-cross-certified-subordinate-ca-extended-key-usage---restricted) | [^eku_ca]: While [RFC 5280, Section 4.2.1.12](https://tools.ietf.org/html/rfc5280#section-4.2.1.13) notes that this extension will generally only appear within end-entity certificates, these Requirements make use of this extension to further protect relying parties by limiting the scope of CA Certificates, as implemented by a number of Application Software Suppliers. [^name_constraints]: See [Section 7.1.2.10.8](#712108-ca-certificate-name-constraints) for further requirements, including regarding criticality of this extension.